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On June 30, 1943, Flight Sergeant Colin Duncan and his squadron of Spitfires took off on a mission to intercept Japanese aircraft over Darwin. But while the ensuing battle has for decades been marked in folklore, the whereabouts of Duncan's shot-down plane has, until now, remained a mystery. The Spitfire A58-2 Duncan was flying caught fire, engulfing the cabin in flames and sending the aircraft plummeting towards the ground in a spiral dive. Desperate to escape, the rip cord to release his aircraft canopy failed, leaving Duncan scrambling to force it off and struggle out of the aircraft to parachute to the ground. Flight Sergeant Colin Duncan defied death to make it back to Darwin.(Supplied: Australian War Memorial) But his battle was only just beginning. Duncan was stranded with severe burns in tough Top End terrain, alone and with minimal supplies, and it would be another five days before he was rescued. Bombing of Darwin: 70 years on On February 19, 1942, Japanese forces launched air raids on Darwin. Hundreds were killed in the attack. This compilation of videos, pictures and recollections take a look a of the most significant moments in Australian history. Seventy-six years since that fateful flight, Colin Duncan's grandson has visited the wreckage of his grandfather's plane for the first time. As he walked through the untouched debris of the Spitfire's final resting place, Duncan Williams was left shocked. "It's a genuine time capsule," he said. "I didn't expect it. I don't know what I was expecting really. Mr Williams said he was amazed his grandfather managed to escape alive. On viewing the wreckage, he remarked on how the Spitfire hit the ground with such force it left only a mangled mess of metal. "He was very lucky to get out alive," Mr Williams said. "Here we've got the cannons. You can see the angle the plane hit the ground. The aircraft wreck is now protected under the Northern Territory Heritage Act.(ABC News: Ian Redfearn) The remote location in Litchfield National Park, about 110 kilometres south of Darwin, means the Spitfire has remained undiscovered until recently. And with the crash site immensely difficult to reach and only accessible by helicopter, the plan is to preserve the wreckage at its final resting place. 'This is our Pearl Harbour' The RAAF has handed ownership of the wreckage to the Northern Territory Government in the hope it will help tell the story of Darwin's role in World War II. According to RAAF Air Commodore John Meier, the new find in the Top End outback is testament to the Darwin's often forgotten place in modern wartime history. Hundreds were killed in air battles over Darwin during World War II.(ABC News: Ian Redfearn) "We only had a few Spitfires in Australia, and this one is of major significance because it was lost in the battle of Darwin," he said. "If you compare it to Pearl Harbour, that everyone knows about, this is our Pearl Harbour, and it's not particularly well known by the Australian population." Colin Duncan continued flying Spitfires in the war, and later played cricket for Victoria as well as running a successful building company. He died in 1992 from cancer, leaving behind his wife and two daughters.

Before the glamorous flyers of the 1930s like Amelia Earhart, “Chubby” Miller and Nancy Bird Walton, another woman opened the way to the skies — and were it not for a tragic twist of fate, her name might now be just as familiar. Her name was Millicent Maude Bryant, and in early 1927, she became the first woman to gain a pilot’s licence in Australia. She was also first in the Commonwealth outside Britain. Millicent Bryant c.1919. Portrait by Monte Luke. Author provided A boundary-pusher who met an untimely end Millicent was born in 1878 at Oberon and grew up near Trangi in western New South Wales. Her family, the Harveys, moved to Manly for a period after a younger brother, George, contracted polio (one of the treatments was “sea-bathing”). She met and married a public servant 15 years her senior, Edward Bryant. They had three children but the couple separated not long before Edward died in 1926. Later that year, Bryant began instruction with the Australian Aero Club at Mascot in Sydney. At the time, the site of the current international airport was just a large, grassy expanse with a few buildings and hangars. Bryant was accepted by the Aero Club’s chief instructor, Captain Edward Leggatt (himself a noted first world war fighter pilot), soon after the club had opened its membership to women. Even then, though, she was unusual: here was a 49-year-old mother of three taking up the challenge of flying which, in the 1920’s, was still as dangerous as it was exciting and glamorous. Millicent Bryant (second from left) with other aviators beside her De Havilland Moth. Author provided courtesy of Mary Taguchi. She quickly progressed, ahead of two other younger, women students, and made her first solo flight in February, 1927. By this time, newspapers all around Australia were following her story, and in late March she took the test for the “A” licence that would enable her to independently fly De Havilland Moth biplanes. She passed, and with the issue of her licence by the Ministry of Defence, Bryant was acclaimed as the first woman to gain a pilot’s licence in Australia. Millicent Bryant’s training certificate from the Aero Club of Australia (NSW Section). Her ‘A’ Licence was issued by the Department of Defence in April, 1927 Why, then, isn’t she better known in our day? While Bryant immediately began training for a licence to carry passengers and flew regularly in the months that followed, it was her particular misfortune to step onto the Sydney ferry Greycliffe on its regular 4.14pm run to Watson’s Bay on November 3, 1927. Less than an hour later, she was among 40 dead after the ferry was cut in half off Bradley’s Head by the mail steamer Tahiti. It was Sydney’s worst peacetime maritime disaster. Bryant was still only 49. Her funeral two days later was attended by hundreds of people and accorded a remarkable aerial tribute, as the Wellington Times reported: Five aeroplanes from the Mascot aerodrome flew over the procession as it wended its way to the cemetery. As the burial service was read by the Rev. A. R. Ebbs, rector of St. Matthew’s, Manly, one of the planes descended to within about 150 feet of the grave, and there was dropped from it a wreath of red carnations and blue delphiniums … Attached to the floral tribute was a card bearing the following inscription: 5th November, 1927. With the deepest sympathy of the committee and members of the Australian Aero Club — N.S.W. section. A pioneer in life as well as the sky Bryant’s story quickly lapsed into obscurity. Fortunately, some 80 years later, the rediscovery in the family of a collection of letters and other writings has enabled Bryant’s life beyond her flying achievement to be rediscovered. The letters were — and are still until they are added to the collection of Bryant’s papers in the National Library — held by her granddaughter, Millicent Jones of Kendall, NSW, who rediscovered them in storage at her home. The main correspondence is a conversation with her second son, John, in England. It covers the period she was flying, though it only moderately expands on the flights recorded in her logbook. However, her letters and writings reveal much more about Bryant herself, her relationships, her feelings and her leisure, business and political activities. And they make it apparent that she was as much a pioneer in life as well as in the sky. A clipping from The Bulletin, February 24, 1927. The Bulletin., Author provided For one, flying was not Bryant’s only unconventional interest. She was also an entrepreneur, registering an importing company in partnership with John, who went on to become a pioneer of the Australian dairy industry. She opened a men’s clothing business, Chesterfield Men’s Mercery, in Sydney’s CBD. However, disaster struck when it was inundated with water mere weeks after opening, following a fire in the tea rooms upstairs. Bryant then became a small-scale property developer, buying and building on land in Vaucluse and Edgecliffe. She’d been well tutored in this by her father, grazier Edmund Harvey (a grandfather of billionaire Gerry Harvey), whose own holdings eventually included a large part of the Kanimbla Valley west of the Blue Mountains. An excellent horsewoman, Bryant was also an early motorist who had driven over 35,000 miles around NSW and who could fix her own car. She was a keen golfer and reader and even a student of Japanese at the University of Sydney. A key writing fragment by Millicent Bryant (c.1924). Author provided Several fragments of a family saga she planned to write, based on her own life, are among her papers. One sheet, entitled “A Life”, summarises in a series of rough notes rather more than she might have told anyone about her inner world. Marriage – mistakes – children – despondency. Ill-health. Great desire to “live” and create things… She notes that a trip abroad was a complete success but it furnished a heart interest which lasted for fourteen years until hope died owing to a marriage. This fragment provides some background to her taking, in her forties, the unusual step at that time of leaving her marriage and family home to start life afresh with her sons. This was not long before she took her first flight, probably with Edgar Percival, a family friend and later a successful aircraft designer whose planes won air races and were noted for their graceful lines. Vigour, values and conflicts Growing up in the NSW inland late in the 19th century, Bryant would have begun with a fairly traditional view of what it meant to be a wife and mother. However, her early life was also “free-spirited” (as one newspaper described her upbringing) and her determination to make decisions and shape her own life put her on a collision course with gender role expectations common at the time. Learning to fly, especially in middle age, was a breakthrough she pursued perhaps even more keenly after being denied work with the Sydney Sun newspaper solely because she was married. Bryant clearly came to hold strong ideas about what a woman could and couldn’t do, and her life shows a determination to make her own path, despite confronting obstacles that are still familiar in our own time. Bryant is not just a figure in aviation history. Her life — spanning the colonial period, the newly-federated nation and the tragedies of World War I — came to reflect the vigour, values and conflicts of Australia in the early 20th century. In 2006 a new memorial to Millicent Bryant was placed in Manly (now Balgowlah) Cemetery. It was dedicated by the late Nancy Bird Walton, pictured with Gaby Kennard (left) the first Australian woman to fly a single-engine plane around the world, and (right) a great-great-granddaughter of Millicent Bryant, Matilda Millicent Power-Jones. Author provided, Author provided

Queensland motorists could get a rare glimpse of two vintage Royal Australian Air Force (RAAF) planes as they are escorted by police convoy on a 1,600-kilometre road trip across Queensland. The Mirage fighter jet A3-55 and Winjeel Trainer A85-403 started their journey just after midnight Friday from the Amberley RAAF base. The restored aircraft were expected to arrive in Townsville on Sunday to go on permanent display at the RAAF's Aviation Heritage Centre, ahead of next year's Air Force Centenary. The convoy will be stopping about every two hours with overnight stays in Banana and Moranbah. Other towns that are expected to see the aircraft include Toowoomba, Dalby, Chinchilla, Miles, Wandoan, Taroom, Theodore, Dululu, Dingo and Charters Towers. Planes restored 'to former glory' The Mirage, or French Lady, was a single-seat frontline fighter that flew between 1967 and 1987, capable of a speed of more than 2,000 kilometres an hour and was armed with guns, missiles and bombs. The Winjeel — an Aboriginal word for 'young eagle' — was a basic flight trainer that flew between 1958 and 1975. They have been restored by members of the Amberley RAAF Base's Air Force History and Heritage Branch. Warrant Officer Mike Downes has joined the convoy and said it was a unique spectacle of aviation history. An historic photo of the Mirage fighter jets in flight.(Supplied: Department of Defence) "I'm a bit of an aviation nut, I love my aircraft," WOFF Downes said. "The interest level has been generated in places like Claremont and Moranbah and Banana. "People say I used to work on that or my father flew them." Part of the restoration included clearing out the cockpit and a new lick of paint. "We've painted the aircraft in the colours of number 76 Squadron so it represents the colours that that aircraft operated in back when it was flying," WOFF Downs said. Winjeel Trainer A85-403 left Amberley on Friday and is expected to arrive in Townsville on Sunday.(Department of Defence) 'It will take up most of the road' WOFF Downes said it has taken about a year to organise the logistics, including police escorting the Mirage. "We've taken the wings off the Winjeel so it's quite a narrow load," he said. The wings of the Winjeel have been removed.(Supplied: RAAF) "The Mirage is a different story completely, it's actually 8.2 metres wide from wingtip to wingtip so it will take up most of the road." He said flying the aircraft to Townsville would have required a rebuild. "It would be a mammoth task to make it air-worthy," he said. "This aircraft has been turned into a static display aircraft so we've removed the engine and a lot of the other equipment." The Mirage will be escorted by a police convey for the entire journey. The two aircraft will meet up in Charters Towers before heading to their final destination.

Australian company AMSL Aero has unveiled what it claims to be the world’s first electric air ambulances, launching the first prototype aircraft in Sydney on Wednesday as part of a partnership with air-rescue organisation CareFlight. The Vertiia prototype has been designed to take-off vertically, like a helicopter, but once airborne, flies with the aid of fixed wings, in the same way as a plane does. AMSL Aero says that this combination provides the aircraft with significant flexibility in where it can land, while also providing greater speed and energy efficiency. The company says that the aircraft would reach a cruising speed of up to 300 km/h and a range of up to 250km as an all-electric model with batteries, and a hydrogen fuelled version achieving a range of up to 800km. The aircraft was launched by deputy prime minister and transport minister Michael McCormack, who welcomed the prospect of an all-electric aircraft that had the ability to access difficult areas. “I remember growing up and watching the Jetsons and marveling at that futuristic technology. It’s right here, right now and it’s happening,” McCormack said. “What an exciting day to think that we’ve got a what will be a carbon neutral plane taking off, landing, in sites where there’s a mass casualty or indeed a hospital where somebody’s young, or somebody not so young, needs urgent medical retrieval and in sometimes even country areas, you can’t get to places easily” AMSL Aero CEO Andrew Moore says the vertical take-off and landing (VTOL) allows the aircraft to access areas without the need of a runway, and it had entered into a partnership with CareFlight for the development of an “electric aero ambulance”, that could provide crucial medical support to regional communities. Deputy prime minister Michael McCormack, with AMSL Aero co-founders Andrew Moore and Siobhan Lyndon. “Vertiia will instantly enable greater access to medical services for vulnerable remote, rural, and regional communities, offering new models of care through rapid and low-cost connectivity,” Moore said. “Unlike aeromedical planes that require a runway, Vertiia will carry patients directly from any location straight to the hospital, significantly reducing the complexity and time transporting vulnerable patients. “It will also be quieter and safer than helicopters, and will eventually cost as little as a car to maintain and run, transforming aeromedical transport into a far more affordable, accessible, safer, and reliable option.” CareFlight’s medical director Dr Toby Fogg said that the organisation had been attracted to the Vertiia aircraft, as its efficiency and lower operational costs, while providing the same flexibility as a helicopter, meant that it could potentially deploy more aircraft for the same cost, reaching more people needing assistance. “Initial scoping and modelling suggest that with Vertiia we would be able to reach more Australians. For example, the price point of operating Vertiia versus helicopters and fixed wing aircraft would mean we can purchase a much larger fleet aircraft, by several multiples. The lower operational costs would allow us to hire more doctors, nurses and paramedics,” Fogg said. AMSL Zero was founded in Australia in 2017 by co-founders Andrew Moore and Siobhan Lyndon with the initial versions of the aircraft having the ability to carry a pilot, a medic as well as transporting a patient. The partnership between AMSL Aero and CareFlight is being supported as part of a $3 million Cooperative Research Centres Project grant, and would include the University of Sydney and autonomy and sensing specialists, Mission Systems as part of the collaboration. CareFlight pilots will be involved in the design of the Vertiia aircraft, ensuring it meets the needs of medical services and could see electric air ambulances deployed within the next few years. The company already has its eyes set on the creation of a commercial version of the aircraft having the capacity to transport up to four people. Both the all-electric and hydrogen fuelled versions of the aircraft have the potential to operate with zero associated greenhouse gas emissions. A prototype of the Vertiia aircraft was unveiled at AMSL’s aerodrome located at Bankstown Airport in Sydney, where the aircraft has been undergoing construction. The aircraft is expected to undertake test flights from a facility at Narromine Airport, just outside of Dubbo. The Vertiia aircraft is being touted as one of the world’s most energy efficient aircraft and has the potential to be deployed in a range of applications, including commercial transport and flying taxis.

Bundaberg’s Jabiru Aircraft has created face shields with the help of 3D printing to provide extra protection for frontline workers dealing with Covid-19 cases. Bundaberg’s Jabiru Aircraft Pty Ltd, whose business usually focuses on producing light sport aircraft and engines, has responded to the current pandemic crisis by creating face shields utilising 3D printing technology to provide extra protection to frontline health workers dealing with Covid-19 cases. With these efforts Jabiru Aircraft joins other manufacturing entities and individuals around the world in producing emergency Personal Protective Equipment (PPE) during a time of global shortage. Jabiru Aircraft Business Manager Sue Woods said last Friday she and an employee, engineer Alex Swan, were looking at ways to support health care workers during the current public health situation, and with a little ingenuity and the help of a 3D printer they were able to design and commence the manufacture of the PPE. Sue said they were very concerned for the wellbeing of paramedics, GPs and medical personnel who were most at risk of contracting the virus. They hoped the extra layer of protection offered by the face shield would keep these essential people healthy. Both Sue and Alex have family members who work in healthcare, and they were on the same path of thinking – wanting to ensure not only their loved ones stayed safe, but also others facing the Coronavirus firsthand. 3D printers used to create face shields “I came to work one day after watching footage on the shortage of PPE and thought ‘what can we do'?” Sue said. “Alex experimented with cutting the visor section until we had the right shape and he modified the headband 3D file to accommodate glasses underneath. “We then had both a local dentist and a local doctor try the face shields, and check with sterilising products, and we had good response.” Jabiru Aircraft Pty Ltd has designed and manufactured emergency Personal Protective Equipment (PPE) during a time of global shortage in result of the Covid-19 situation. Two 3D printers are used by Jabiru Aircraft to create the head band for the face shield and the transparent polycarbonate for the visor is cut to shape with a flatbed CNC router. “Our engineer Alex Swan has been very motivated with this project and volunteered much of his own time, getting up in the middle of the night to keep the 3D printers going 24/7,” Sue said. “We have two 3D printers and Alex took them home so he could get up at 2am to press the button to start the next headband.” Sue said it took less than a week to develop the idea and start production of the face shields, and they hope to have 100 finished and shipped to paramedics in Western Australia by Monday. She said the slowest part of the production was the 3D printing and she was thankful for the support from other local organisations who offered assistance. “To increase our production rate of the 3D printed component, CQUniversity Bundaberg and Gladstone and Makerspace Bundaberg and Hervey Bay, along with CQUniversity Makerspace have jumped on board very quickly, and we now have several additional 3D printers in action,” she said. “We are also getting offers of assistance from schools in the local community.”

Time has flown by with November 23 marking the 90th anniversary of the first flight from what was the Western Junction Aerodrome and is now the Launceston Airport. The first flight in 1930 was undertaken by pilot Joe Francis in the Gipsy Moth VH-ULM, leased by the Defense Department to the Tasmanian Aero Club. Club historian Lindsay Millar said the first flight was crucial to aviation in the state. "That first flight really marked the beginning of permanent commercial aviation in Tasmania." "From that very beginning, that first flight here at this airport on November 23, 1930, that was the catalyst for everything." The flight led to the formation of Tasmania's first air service, Flinders Island Airways, which eventually, after many different changes and amalgamations, became Australian National Airways, one of the world's largest airlines. Mr Millar said the anniversary crept up on them. "It is amazing and I have been privileged to belong to the Aero Club since 1956. I have been able to share the history of that club in that period," he said. The plane that made the historical first flight is also, once again, touring the skies. The restoration of the plane was started back in 2002 and was completed in 2012 with the original Aero Club colours. The VH-ULM after its restoration was finished in 2012. "The incredible thing about the flight VH-ULM is that the aircraft still exists and is now flying in Queensland," Mr Millar said. "That aircraft after being in private hands for some years and then in a a museum, it's back in the air again, better than brand new." The Tasmanian Aviation Historical Society president Andrew Johnson said it was remarkable the plane was still running. "This aircraft has been restored and looked after and still flying. That makes the whole story really special." Lindsay Millar with model of first flight plane. Mr Johnson said the first flight was the start of quite a significant aviation story in Tasmania. "That first flight led to numerous other flights and to individuals who were pioneers in aviation taking up the concept of flight and developing it from, I suppose a bit of a novelty idea, to commercial flying." "It did pave the way for others." On November 23, the Tasmanian Aero Club rooms will host a special function to recognise the anniversary of the flight and celebrate how far aviation has come because of that moment. "We believe it's an important story and that's why the [TAHS] was formed - to shine some light on it and I think that's the start of it," Mr Johnson said. "From now on we will start to really recognise the events and the significant dates of aviation in Tasmania."

Packing for travelling light Always a problem – so many compromises have to be made. The old adage, "If in doubt, leave it out ...", needs to be applied often, but there's still lots of pondering, hefting, agonizing, and re-packing. I've gone through the process dozens of times over the years, preparing for long backpacking and motorbike trips, and now ultralights. It does get easier, especially with the lightweight gear now on the market, and I have learned a few tricks that I'll pass on to anyone interested. As you'll see, I like my comforts as well, and have found ways to bring them with me, folding chair included! First of all, I would never leave my self-inflating mattress behind. It's 3/4 length, 25 mm thick when inflated, rolls up to a small bundle deflated, and weighs very little. You'd think that thickness (thinness) wouldn't be of much use, but it does wonders for a comfortable sleep! If the cost seems too much (about $90 when I got mine), then at least get one of those blue foam mats. Even 8 mm thickness of that blue foam is enough to make a really big difference on cold, hard ground, and cut down to 3/4 length also weighs very little. To carry the mattress on the aircraft, I use a couple of short pieces of light bungee cord (3–4 mm diameter) tied in loops like strong rubber bands to keep the mattress rolled-up, then another couple of loops of the bungee tied around a convenient tube on the aircraft, and just slip the rolled mattress under these loops — nothing to tie/untie every time, and very secure. Inside the wing would be a good place, if you have access on your aircraft. A sleeping bag is the next obvious necessity for camping out. There are lots of options here, but I find that combining a light-weight sleeping bag with lots of cold weather flying clothing gives the most flexible combinations for all-weather flying and camping at minimum weight. So let's first have a look at flying clothing. Flying warm Having been raised on the central plains of Canada, then spending months at a time living on motorcycles in all weathers has taught me a bit about dressing to survive the cold. I did a lot of suffering in those early days before I learned better. Let's start at the inside, where you can make the biggest gains in warmth. I really don't understand why long underwear gets the jokes and ridicule that it does. It's by far the most effective warm clothing of all, for it's weight. The polypropylene thermal underwear available these days is soft, form-fitting and stretchy, and easily fits under other clothing. It wicks moisture away from the skin and provides a layer of warm air next to the skin, just like I would imagine the layer of fur does for a cat! When not being worn it packs into a soft bundle and weighs very little. The jeans and shirt going over it provide very little warmth for all their weight; far warmer and more comfortable is to travel in a track suit. Over the shirt go a couple of lamb's wool sweaters. These are the soft, fluffy, 'lounging' sweaters, either V-neck, or crew neck to your preference. Two (or more) layers like this is much, much, warmer and lighter than one heavy jumper, and more flexible and comfortable. When not needed they stuff easily into your travelling bag. When your flying jacket goes over all this fluffy bulk you'll feel like a fat teddy bear, but at least you'll be a warm and cosy bear! The sweaters are for sale in 'recycled clothing stores for a couple of dollars each, so not a cost problem, but get a larger size for comfort. (I actually bought a couple of them in Narromine one time, when ferrying an open ultralight from Geelong, and a freezing cold front caught me unprepared; nice and warm all the way after that.) If you wear a flying suit then your legs are already covered, but if you wear a flying jacket, then you need some outer pants – it's no use being a cosy bear on the top while losing all your body heat from your legs. Those insulatedski pants are ideal. They're wind-proof, warm, light-weight, and come well up under the jacket for a good seal. But this isn't all that you can do; don't forget those cold feet. I carry several pairs of light wool socks, and wear two or three pairs at once on a long, cold flight, with another couple of dry pairs to change into at fuel stops. Another important bit of clothing is a scarf, to seal around the collar of your jacket, and protect the back of your neck. I just use a T-shirt for the purpose, since it can double as a spare shirt as well. Even more effective is a balaclava, which will seal in the whole head and neck. For the hands, ski gloves with the tips of the fingers cut off, work well for me – warm and still have good dexterity. Dress like this and you won't be cold, regardless of the conditions. I know that all this seems like a lot of stuff, but the extra, besides what you would wear anyhow, doesn't weigh much at all, and much of it will double for your sleeping gear as well. Of course, the other advantage of all these layers is that you can arrange them to suit the conditions at the time, whereas if you depend only on a very warm flight suit, it can be stifling on a hot day, and yet too bulky and difficult to pack away. Sleeping Sleeping warm So I just carry a lightweight summer sleeping bag all year. But a roomy one, because inside it I wear as much of the flying clothing as is necessary for the temperature of the night. I don't know where the myth comes from about it being warmer in a sleeping bag with your day clothes off — I find just the opposite, and I've had many teeth-chattering nights to put it to the test. There are several advantages to wearing lots of clothing inside a sleeping bag; not the least of which is, if you need to get up in the middle of the night for whatever reason, it's no sense exposing any more skin than necessary to that chill night air! As a minimum I use my thermal underwear as pyjamas, and if the night is cold enough, then my track suit pants and a jumper as well. The track suit pants are the ones with two layers of light fabric rather than the thick fleecy ones — lighter and easier to pack away. Then when I get up in the morning to stir up the fire, I'm already dressed enough to be comfortable, without having to get into cold clothes. If it's a really freezing cold night then I'll wear everything (except jeans, they're just too uncomfortable), including flying jacket and ski pants, not forgetting a couple of pairs of dry wool socks and the T-shirt wrapped around my head. With all these options I can be comfortable anywhere from the tropics to the frosty high plains. The sleeping bag should have a hood to keep your head warm, since 20% of body heat is lost there. And it must not have a fleece lining — the fleece feels nice on bare skin but it drags on your clothing when you roll over, and collects every bindi [burr] in the west if it gets a chance. Sleeping really light The next essential for lightweight camping is a 'space blanket' (that may be a trademark name, but I'll use it anyhow). It's also an essential part of any survival kit so I have a space blanket permanently in my aircraft, even for local flights; once again it weighs little and is held in by a couple of loops of light bungee cord around a convenient tube. When camping really light, I use the space blanket as a ground sheet, pulled partly over the sleeping bag on the side which any draught is coming from. Stopping that draught from getting at your back makes a really big difference to staying warm at night. Putting another space blanket right over the sleeping bag sure is nice and warm, but condensation will wet parts of the sleeping bag — but if it's raining it's still a lot better than cold rain soaking the bag. If the second space blanket is set up like a lean-to, with a fire in front, it's like a reflector oven and is the warmest camp of all! Avoid the cheap imitation space blankets on the market, made of that blue tarpaulin material aluminized on one side — they're much heavier and stiffer than the original brand 'Space Blanket', and not nearly as useful. One last essential for sleeping out is a mosquito net! It only takes one persistent mossie at 3 a.m. to ruin a good sleep (and if there's one buzzing around you, others will hear the buzz and come over to get their share). The lightest solution that I've found is to carry one of those fly nets that fits over a hat. So I sleep under my hat and try to tuck the net into the bag — it's awkward and prone to coming loose if I roll around to much, but sure is better than trying to breathe inside the sleeping bag on a tropical night! Five star accommodation Of course the way to really beat the mossies, and get a whole lot of other comforts as well, is to have a tent. And that's possible these days with the light-weight tents on the market. Mine weighs just 2 kg, and is a great little 'cocoon'. It not only keeps the mossies well away, but it stops that chilling draught, keeps the dew off, and provides shelter to keep my gear and boots dry if there's rain in the night. I used to 'sleep rough' with only a ground sheet and sleeping bag, but now I'm hooked on the comforts of my little tent. So what doall those 'very littles'add up to? The flying clothing — ski pants, track suit pants, 2 sweaters, T-shirt, gloves, 5 pairs socks, and thermal underwear — weigh 3 kg. (The flying jacket is so much a part of me that I consider it as part of my personal weight.) The sleeping bag, mattress, and 2 space blankets add another 3 kg, and the optional tent is 2 kg. Stuff it all into a light-weight sports bag (along with a small pillow for real comfort) and that's9 kg — not too bad for a kit that's sufficient for flying and sleeping-out in just about any weather, and in reasonable comfort. Basic survival gear Every aircraft should always carry some basic survival gear, even on short local flights. That may seem a bit extreme to most casual fliers, but let's have a think about it, and maybe you'll decide to carry at least the basics in future. Hopefully it'll never be needed for a critical 'survival' situation, but much more likely just an unplanned night spent out somewhere, due to bad weather or mechanical failure. Water In this hot, dry Australian land it's really amazing to see fliers ignoring all lessons of common sense by flying off without any water at all on board! Even without the possibility of being stranded by an emergency landing, it's really nice to have some good drinking water at hand. I always have at least two litres of water in my aircraft — one litre bottle right handy for a refreshing drink whenever it suits, and another litre bottle secured in the pod. That's enough, if used sparingly, to make a really big difference if I get stranded somewhere overnight. Two litres is the absolute minimum, but if you're going away from the settled coast and the weather is really hot then of course much more is required. To carry more water the best containers these days are those tough nylon water 'bags' sold by good camping stores — much easier to pack into corners of the pod, or wherever, and easier to tie down than hard containers. They're also handy for trimming the balance of an aircraft (seems ridiculous to see some aircraft with a lump of lead permanently in the tail, when a few litres of water would have the same effect, and be a handy reserve as well!) Space Blanket This is the most useful survival equipment you can carry; it could save your life in either hot or cold conditions. I have one permanently secured in my aircraft. It weighs less than very little and is easy to roll up and tie to some tubing somewhere out of the way. One of the most likely causes of being forced down is due to bad weather, and that might well mean being caught out in cold rain for a couple of days or more. No shortage of water, but without shelter it could easily get to hypothermia. In extreme cold, wet conditions it's best to crouch down, or sit in the aircraft seat, with your knees against your chest, trying to be as small as possible, with the space blanket over your head and around you like a shawl. This way you best contain your body heat and shed the cold rain. It gets pretty cramped and uncomfortable, but you can at least survive in some really cold conditions this way. If you have the means of lighting a fire and keeping it going, then the the space blanket rigged as a lean-to can turn a survival situation into real comfort. In the event of being stranded in hot weather, the space blanket once again is a saviour. If you have limited water, then it's very important to reduce the losses. Watch kangaroos for a good lesson on how to manage these conditions. During the heat of the day, especially in drought conditions, they select the best shade they can find and then just lie there without moving at all — same should go with us. Chasing around looking for bush tucker or digging for water is usually a complete waste of precious energy. Tie the space blanket over some low bushes, crawl underneath with the water you have, and lie absolutely still. Try to 'slow down' and get into a state of slumber, breathing as slowly as possible through the nostrils, and stay that way; you can survive much, much longer in this state of suspended animation than if you were up and moving around. Let's hope it never comes to this extreme for any of us, and it shouldn't if you carry an ELT, but it's good to know, just in case ... Fire lighters I always keep at least two of those gas cigarette lighters on hand, one inside the rolled up space blanket, with another one always in the shoulder pocket of my flying jacket. Some purists insist on matches, but my experience indicates that the lighters are much better than even the best 'waterproof' matches — with those lighters that have an adjustable flame it's like lighting a fire with a blow-torch! In Australia it's nearly always possible to find enough suitable wood to light a fire, and that fire can be really essential for survival. With the space blanket rigged as a lean-to in front of a good fire, you can be dry and cosy. Light the fire against a log, with a couple of heavy bits stacked across on top, and it reflects the heat into the lean-to as well as protecting the fire from the rain. VERY IMPORTANT! A campfire isn't all that visible from the air unless it has a good plume of smoke in daylight or a flare-up at night. So if you're depending upon an aerial search (due to your ELT signal of course), then keeping a good fire going is essential. Have a bundle of foliage ready to throw on to make lots of smoke in the daytime, or a big bundle of light branches on hand to make the fire flare up quickly at night, in case you should hear an aircraft approaching. Mirror Another way to assist a search aircraft, or even possibly attract the attention of any passing aircraft, is with a signalling mirror. A bright, persistent flash from the ground really catches the attention, and that's easy to do if you have a mirror on a sunny day, and know how to use it. The plastic ones from camping supply are light and easy to carry, so is a CD; mine lives in the map pocket, but inside the space blanket would be good. It should have a hole in the middle; if not then drill an 8mm hole. To use it, hold the mirror against your eye with the reflective side away, peeping through the hole at the aircraft. Reach out with the other hand as far as you can, holding a finger tip in line with the target, and adjusting the angle of the mirror to shine the reflection onto the finger tip. Practice it with a friend at your airfield and you'll see how brilliant and distinctive the flash is, even at a great distance. ELT Well of course every aircraft should carry an Emergency Locator Transmitter. The little pocket ones are excellent, and affordable — no logical reason not to carry one these days. They're really effective, as I've proven a couple of times — both times I could have been rescued really quickly if the emergency was real. Those false alarms were just embarrassing, but it's very consoling to know that the system works so well. But the ELT must 'live' in the aircraft at all times, even for short local flights. Work out some form of mounting so that the ELT is permanently near at hand, but can be quickly removed if a speedy exit is needed. Food Food is certainly the most over-rated item in most survival manuals. All that talk of chasing around looking for little bits of 'bush tucker' and trapping animals is nonsense — far better to just lay still and conserve the reserves of energy your body already has in store. We can all go for a couple of days without any food at all, and some could even benefit from the enforced diet! Some care also needs to be taken in selecting food to carry along. For example, the often recommended 'beef jerky' would be absolutely the worst selection I could think of — not only is it a desiccated product that needs water to reconstitute, and salty that needs water to balance, but all such meat protein foods need even more water for the digestion process. It's not as if we need body-building protein in that situation — we need energy, easily digested energy. So I carry tubes of Nestle's sweetened condensed milk! Yes, it's by far the best 'survival' food that I can find. It has heaps of sugar for that instant energy, and milk for sustained energy, and the little bit of fat and protein that makes the stomach feel like it's had at least a bit of a feed. If you also have a little billycan hidden away in the aircraft, then Nestle's milk in hot water makes a very warming and sustaining drink on a cold, wet night. In a pinch you can just suck it out of the tube, along with comforting memories of childhood. So, inside my rolled up space blanket I also carry a tube of Nestle's, just in case ... I usually have several muesli bars stashed away in a pocket under the seat of my aircraft. They're for snack food and 'flying breakfasts', but would make good survival food — if enough water was at hand. Repellant Last, but not least, I reckon insect repellant is an essential to good survival. Not only do mossies drink your precious blood, but a night spent fighting them means the next day being so tired that you can't even think straight — and sufficient rest for clear thinking really is an essential for survival. Many survival crises have been made much worse by muddled thinking and panic, often brought on by exhaustion, so this is important. Just the smallest bottle available, or those individually packaged 'wipes', is all that's needed. Clothing Shouldn't even have to mention this, but a hat can make a real big difference for comfort, and even the chances of survival in either cold rain or hot sun. If you don't wear a hat regularly, then at least include one in the survival kit. My insulated flying jacket comes with me in the aircraft all the time, winter and summer. My ski pants are stashed out the way in the wing all the time. With the jacket and ski pants and the space blanket, and a good fire, I can be pretty comfortable on even a very cold night. So the minimum 'survival kit' that I reckon should be in any aircraft, all the time, (space blanket, lighters, mirror, repellant, ELT ) weighs less than a kilo, plus two kilos of water. So that's 3 kg for enough gear to survive for a day and a night without too much distress – sure sounds a lot better to me than being out there with nothing! STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

One of my early instructors was a highly pessimistic individual, always muttering about 'What if this bit fell off, how would you cope with it?" and other such comments full of joy. Over the years however, I have come across a number of incidents where things have fallen off, with widely differing results. A few years ago a gliding friend suffered a failure of an aileron quick-release control rod which caused the free aileron to flutter. An uncomfortable but still somewhat controllable situation. Unfortunately when she tried to turn the glider the loose end of the rod jammed in the structure and resulted in a high speed fatal descent. Another friend found himself at the top of a glider winch launch with no elevator control and escaped by parachute from only 600 feet. A third gliding friend flying a Nimbus 3 (an 87 feet span monster with several flap/aileron sections) aero tow-launched after a servicing during which the controls 'adjusted'. The test flight revealed the glider would only circle to the left despite full right aileron and rudder. After an interesting launch, where the tug pilot managed to turn and climb at the best rate for the glider, he was dropped off tow high enough to bale out. By experimenting with various speeds, flap and airbrake settings he managed to control it just enough to return to the airfield. By having a sound knowledge of the aircraft and approaching the problem in a calm efficient manner this pilot recovered a situation which might have ended very differently. The aim of this article is to encourage pilots to think about how they might cope with a control problem, and what aspects of the aircraft behaviour might be of assistance. While most control failure problems can be avoided by suitable maintenance there is always the possibility that one day you may find yourself with such a challenge. The key to surviving such an experience is a thorough knowledge of the handling characteristics of the aircraft, particularly the secondary effects of controls. Control failure modes Control failures, be they caused by mechanical failure, collision or structural failure will probably result in one or more of the following: restricted or no movement of the control surface surface floating free and probably fluttering to some extent surface missing completely, or connected by control cables and probably flailing around behind the aircraft major application of one or more controls to remain in a desired attitude/heading. Pitch control Perhaps the most critical control and also the one with most options, as most aircraft can be controlled in pitch in a number of ways. Adjusting the power setting will usually result in a trim change. Coarse or gentle applications of power may have different effects on attitude, descent rate and the all-important airspeed. Varying the power will also adjust torque and slipstream effect, thus assisting, to a small degree, with roll control. Aerodynamic trim tabs (those that sit on the trailing edge of the elevator) may be of some use. If the surface is jammed the tab will work like a small, albeit not very effective, elevator, although the lever must be moved the opposite way to the control column. (Trim lever forward will raise the nose). If the elevator is floating free (and not fluttering) the trim lever may be used in the same sense as the control column. Bank angle is an effective way of controlling pitch. We all know that as we enter a turn the nose tends to drop unless we counter it. It is possible to use bank angle to lower the nose and hence control the speed. You will of course be in some sort of (probably descending) turn but the turn will be partially controlled and that is better than spinning or stalling. The steeper the bank, the more the nose pitches down. By adding pro-turn or anti-turn rudder more control is available. This method gives you a reasonable degree of control over speed, in return for some height loss and the increased risk of a cross-controlled stall. Centre of gravity. If your aircraft has more than one tank and you can transfer fuel you may be able to adjust the attitude by moving fuel. Even leaning forward or back will have some effect. It's not much but it's better than nothing. A Miles Messenger escaping to England during WW2 lost its entire engine after one propeller blade was shot away while crossing the Channel. The family aboard all piled into the front seats and the aircraft glided just above the stall to shore and a successful landing! Several aircraft have approach control devices such as flaps or spoilers. These controls usually have some sort of trim change associated with their operation. Some higher performance gliders use flap settings even more than the elevator for controlling pitch, relegating the elevator to little more than a trimming device for much of the time. Roll control In the event of loss of the ailerons some degree of roll control is available by using the secondary effect of rudder. While not an efficient way to turn the aircraft you should have at least some directional control. Short or rapid bursts of power may increase the effectiveness of the rudder to some degree. Power, in the form of torque and slipstream effect may also be of use. Yaw control Loss of the rudder, as long as the aircraft is kept away from a stall/spin poses the fewest problems as long as the effects of power and adverse yaw are understood. Bank angle can be used to counter any yaw tendency (from torque or a damaged fin while in flight) and care must be taken to allow for adverse yaw when entering or exiting any turns. Effect of airspeed The various trim changes associated with controlling the aircraft change with the airspeed. Adverse yaw for example, decreases with an increase in airspeed. The aircraft should be flown at a speed safely above the stall but no faster, unless the increase in speed provides more control. If a control surface is floating free it will tend to flutter and the violence of the flutter will increase with speed. Other methods Some aircraft have doors or canopies fitted which if opened in flight may well provide some sort of trim change. It may or may not be of use but it is worth considering. If the aircraft is approved, the manufacturer may be able to supply information on what happens when a door is opened in flight. Unless the door is approved for opening in flight it should not be practised, but in an emergency ... Control on the ground If possible try to find somewhere to land which is large, long and flat, and as into wind as possible. On the ground the ailerons (or more accurately, adverse yaw) can be used to aid in directional control. (Use left aileron to turn right). Those with differential brakes can make use of them for some directional control. As many of us fly taildraggers with single brake controls, use brakes only gently and while travelling straight. Heavy braking when the aircraft is starting to swing will accelerate the impending ground loop. Considerations When faced with some control problem you should endeavour to place the aircraft in a reasonable attitude with sufficient speed for normal flight or as near as possible to it. Assess the failure as to what type (whether the failure is a structural or mechanical one and whether the surface is still there, fluttering etc.), which control(s) are affected and the various secondary effects that can be used to help. In the event of a structural failure or collision the airframe integrity will already have been compromised and so the aircraft should be landed as soon as possible, once some manner of control has been established. Extending flaps or spoilers, or opening doors on a damaged airframe may compromise the structure further so, unless control is inadequate, leave flaps where they are. If the control surface or the structure is fluttering, once again, land as soon as control is established. Flutter can be very violent and destructive, and will increase dramatically with airspeed, so aim to fly at the minimum speed where you still retain sufficient control. If the control failure is a restriction or loss of movement and you have the aircraft under sufficient control, it may be flown to a more suitable area for landing. However, continue to monitor the problem and be prepared to land immediately if there is any sign of the problem compounding. All of the above methods of alternative control, even those that only provide a small measure of assistance, may well add up to the difference between surviving a control problem or not. Even if you never have a control failure, considering the above methods will hopefully make you more aware of the aircraft's habits and so improve your flying skills. Many of these methods may be practised safely at a suitable height. For example, trim the aircraft to fly "hands off' and try a number of climbing and descending turns, rolling out onto specific headings, using rudder and effects of power. With an aircraft as responsive to secondary effects as a Drifter it is possible to fly entire circuits without touching the stick, but it is best to practise this with an instructor. Hopefully none of us will ever have to cope with a control failure but it would be nice to know how the aircraft (and the pilot) might react to one. After all none of us want to have an engine failure but we all practise in case we get one (don't we ... ?). Read the article 'Rooted' in the May – June 2004 issue of CASA's Flight Safety Australia magazine.

7.2.1 Maintaining preparedness Flight planning When planning a cross-country flight some essential actions are required to minimise both the possibility of power loss and the consequences of such: Construct a safe route. Calculate the fuel needs. If using a GPS in flight planning be aware the GPS does not take into account the type of terrain or the height of terrain — the GPS indicated route might be over 'tiger country' (e.g. heavily wooded) or straight through a mountain. Warning: the GPS 'GO TO' function is an emergency use feature only — it should not be used as a substitute for proper route planning. Prior to take-off I suggest you review the groundschool module 'Take-off considerations' before continuing with this section. Check the stopping distance required. The pilot should know the distance required to reach flight speed and then bring the aircraft to a halt. It may be necessary to abandon the take-off shortly after lift-off, due to power failure or just doubtful engine performance or other event — this is particularly important in short field or 'hot and high' take-offs. If take-off and landing distance (over a 50 foot screen) charts are available then the total distance needed to take off, abort at 50 foot, land and bring the aircraft to a halt is just the sum of the charted density altitude take-off and landing distances required. If the distance available is insufficient to take off, reach 50 feet, land and safely bring the aircraft to a halt at the departure, destination and en route airfields, then maybe the planned flight is really not a good idea. Before taxiing ensure all extraneous objects in the aircraft are secured adequately so that they cannot foul the control lines or rudder pedals or become missiles in the event of an emergency landing. In addition you must ensure there is no possibility of anything becoming loose and wrapping around the tailplane, or passing through the propeller disc of a pusher-engined aircraft. Always check the fuel tanks for water, don't change tanks just before take-off, and taxi out and take off on the fullest tank. Always do an engine run-up before take-off which, as well as the usual engine checks, is of sufficient duration to ensure fuel is flowing properly throughout the system. Always plan to gain greatest altitude possible before reaching the airfield boundary, so take off into wind; don't do an intersection take-off; use all the distance available — runway behind you at the start of take-off is an asset stupidly thrown away. If the area outside the airfield boundary is rough, plan to climb out at Vx rather than Vy, and maintain full power until a good height and cruise speed is reached. The extra height gained with distance flown may be very handy if the engine fails. Whether operating from a familiar or unfamiliar airfield, you must have some knowledge of the terrain surrounding the airfield and the position, slope and condition of likely forced landing sites plus associated hazards. If the airfield is unfamiliar then you must ascertain escape routes, potential forced landing sites and hazards during the initial overflight or by ground inspection. After completing your take-off engine and cockpit checks, have a good look at the take-off path and rehearse your emergency procedure for any situation that may occur before you are established at a safe height. 7.2.2 Engine failure after take-off or a go-around Pilots should always be prepared for the possibility that the engine will lose partial or total power during the take-off and climb-out; or, for that matter, at any other time during flight. But, if there is even a suspicion something is not quite right during the initial ground run, the take-off should be abandoned immediately and the aircraft returned to the hangar area for a ground check. It is most unwise to continue the take-off if the engine falters and then picks up, or even if you are just not fully confident about its behaviour. When total or near-total power loss occurs after lift-off the cardinal rule is to 'fly the aeroplane!'; i.e. maintain control of the aircraft. This initially implies quickly getting the aircraft into the right glide attitude and waiting until the speed rebuilds to the appropriate glide speed, then fine trimming. (When changing from climb to glide attitude, the nose has to be pushed down through quite a few degrees, which might feel excessive — particularly if the aircraft was not trimmed to the climb speed.) In circumstances like this, some say the second and third edicts should also be 'fly the aeroplane!' and 'fly the aeroplane!'. During the climb-out the aircraft is at a high aoa, producing very high induced drag — particularly so if climbing at Vx — and when the engine fails, speed decays very quickly, and even more so if the aircraft has a high parasitic drag. The pilot may take three to four seconds to react and move the control column forward, and the aircraft will then take a few seconds to rebuild a safe speed. During these periods the aircraft will be sinking, and if height and airspeed are insufficient the pilot is locked into an immediate and probably very heavy 'landing'. More turn-back information can be read in 'The turn back: possible or impossible — or just unwise?'; also read Mike Valentine's article 'The turn-back following engine failure'. On-field landing If the aircraft is very low when the engine fails the only option is to keep the wings level and land more or less straight ahead — which is no problem if the airfield area ahead is clear. There is little time to do anything but fly the aircraft and close the throttle and also switch off the ignition and electrics. Airspeed is likely to be very low so keep the nose down and the wings level during the descent, using gentle control movements if necessary to change direction slightly. Lower full flap but be prepared for the associated attitude change. You must avoid the possibility of a wingtip striking an airfield marker, fence post or other obstruction — or getting caught in long grass — and causing the aircraft to 'cartwheel'; also the possibility of wheelbarrowing is high. You must also avoid tripping over the boundary fence while airborne, so just get it down (not nosewheel first) and use whatever reasonable means is available to decelerate. Long grass will help slow the aircraft but if necessary, groundloop it to avoid major or expensive obstructions, like a row of parked aircraft. The groundloop is induced by booting in full rudder (and brake) on the side to which you want to swing and will probably result in some wing tip, undercarriage and propeller damage, unless you impact something other than the ground. Off-field landing If some height has been gained but there is no possibility of landing on the airfield then an off-field landing is mandatory. Look for somewhere to put it down but don't immediately fix on the first likely landing site spotted straight ahead of you; there may be a more suitable site off to the side. You have to rapidly assess your height, airspeed (i.e. your energy level) and the turn possibilities available at that height; i.e. can you safely turn through 30° or 45° perhaps even 60° using moderate bank angles and still make it to that much better looking site? Will the wind assist or hinder? It has to be a quick decision because at best you have just a few seconds available to plan the approach. If any doubt, go for 'into wind'. Do not choose the site at marginal distance, even if it's perfect. Close by is better because the height in hand can be used for manoeuvring the aircraft into the best approach position. Because you have no power available you must always have an adequate height margin to allow for your misjudgements, adverse wind shifts, sinking air, vertical gusts and other unforeseen events — and you can dump excess height quickly by sideslipping. Remember that the rate of sink whilst sideslipping is high and the slip must be arrested before the flare. Apart from being clearly within range the choice of landing site is affected by: wind strength and direction ground run availability and direction; a short into-wind site may be preferable to a longer but crosswind/downwind site for an aircraft with a slow stall speed; the reverse applies for an aircraft with a high stall speed. It all relates to kinetic energy and stopping distance approach obstructions; final approach may require some diversion around/over trees, under/over power-lines plus avoidance of other obstructions. Can the near-ground turns be handled safely? Is there sufficient margin for misjudgement and/or wind gusts? ground surface and obstructions, including livestock, during the ground roll. Can you steer to avoid them? Are livestock or kangaroos likely to take fright and run into your path? the energy absorbing properties of the vegetation ground slope: the possibilities of landing downslope may range from difficult to impossible; moderate upslope is good if the pre-touchdown flare is well judged. There is a much greater change in the flight path during the flare; for example, if the upslope has a one in six gradient (about 15°) and the aircraft's glide slope is 10° then the flight path has to be altered by 25° so that the aircraft is flying parallel to the upslope surface before final touchdown. A higher approach speed is needed because the increased wing loading during the flare (a turn in the vertical plane) increases stall speed. If the wind is upslope then a crosswind landing may be feasible if a rural road is chosen can you avoid traffic, wires and poles, particularly in a crosswind situation? a final approach into a low sun should be avoided so that vision is not obscured. All of this is impossible to assess in the few seconds available, hence the need for prior knowledge of the airfield environs and a pre-established emergency procedure for any situation that may occur before you are established at a safe height. As height increases, the options increase for turning towards and reaching more suitable landing areas, making a short distress call and doing some quick trouble shooting. Trouble-shooting When trouble-shooting full or partial power loss remember the first edict — constantly 'fly the aeroplane!'. If the engine is running very roughly or died quietly (i.e. without obviously discordant sounds associated with mechanical failure) and time is available, then apart from the engine gauges, the obvious things to check or do are: Fuel supply: switch tanks (making sure you haven't inadvertently switched to the 'fuel off' position), fuel booster pump on, check engine primer closed. Air supply/mixture: throttle position and friction nut, throttle linkage connection and mixture control position. Apply and maintain carburettor heat (while engine is still warm), setting the throttle opening at the normal starting position. Apply carburettor heat or select alternate air to bypass the air intake filter — which could be blocked by grass seeds or a bird strike. Ignition: position of ignition switches — and try alternating switches in case one magneto is operating out of synchronisation. Or: reverse the last thing you did before the engine packed up. And then: try a restart. There is no point in continuing with a forced landing if the engine is really okay. Cockpit check prior to touchdown Pilot and passenger harnesses must be tight and maybe remove eyeglasses. Seats should be slid back and re-locked in place (if that is possible without adding to the risk) but be aware of the cg movement. Advise the passenger of intentions, warn to brace for impact and advise evacuation actions after coming to a halt. Unlatch the doors so that they will not jam shut on impact. If the aircraft has a canopy or hatch take similar safety action, if that is possible without the canopy affecting controllability or detaching and damaging the empennage. If equipped with a retractable undercarriage, leave the wheels down unless surface conditions indicate otherwise. To minimise fire risk turn the ignition, fuel and electrics off. Handling the approach Once the landing site is decided then choose the ground path for the landing run and select an initial aiming point up to halfway along it. (Once it is clear that the aircraft will reach or overshoot that safety point, then a second point located between the aircraft and that initial aiming point will become the touchdown target with the application of flaps/sideslip.) Continue tracking down the approach path, whilst correcting for any crosswind component, and watching the position and apparent movement of the aiming point relative to the windscreen. Avoid premature use of flaps — although partial flap does help low-speed manoeuvrability and reduces stall speed at the expense of a steeper descent path. At each stage of the approach the aircraft should be re-trimmed to maintain the desired airspeed — and keep it balanced. Watch the top of the highest obstacle along the approach path. If the vertical distance in the windscreen between the top of the obstacle and the aiming point is widening you should clear the obstacle, if it is narrowing you may not. You then have to decide whether you can: (a) accept to hit that obstacle; or (b) safely turn a little onto another landing path; or (c) lower full flap and/or start a full sideslip so that touchdown is made before the obstacle and into vegetation with more suitable energy-absorbing properties. Be aware that dead trees poking above the general tree level may be very difficult to see, particularly if the sun is in an unfavourable position. If the aiming point appears to be moving down the screen you are overshooting (too high) and will touchdown past the target. Lower first-stage flap or start a gentle sideslip and check the result. If you are still overshooting and will safely clear the approach obstacles use second-stage or full flap, or full sideslip (or both if necessary) to steepen the descent path. Prepare for flare and touchdown. If the aiming point appears to be motionless in the screen, the approach slope is good and touchdown would be close to the initial aiming point. At an appropriate position lower full flap, and prepare for flare and touchdown prior to the initial aiming point. If the aiming point appears to be moving up the windscreen you are undershooting (too low) and will touchdown before the initial aiming point. This is no problem if it appears that the touchdown point will still be within the target area — just continue the approach and lower full flap prior to touchdown. If, however, it appears that touchdown will occur before the target area, then lower full flap and head towards the softest vegetation or the most unobstructed area. Whatever you do you must hold the glide attitude. Do not raise the nose until rounding out and never think you can 'stretch the glide'; although ground effect (or water effect) can stretch the float a little. Make a firm touchdown to avoid floating and after touchdown keep the control column fully back. Very severe jolting will make it difficult to hold the feet on the rudder bar but try to maintain steerability, using rudder and brakes, to avoid the worst obstacles and preserve the occupant zone. If appropriate use maximum braking — but avoid locking a wheel — it may not ride over the smaller obstructions. Be prepared to evacuate the aircraft quickly and to grab the fire extinguisher. After evacuation keep well away from the aircraft until any fire risk has abated. If you have a handheld transceiver, broadcast that you are safe or need assistance. Activate your distress beacon if considered appropriate. Partial power loss 1. If loss of thrust is accompanied by extreme vibration or massive shaking of the aircraft (probably due to a propeller blade failure) it is important to immediately shut down the engine to avoid it departing from its mountings. 2. If the engine does not fail completely but is producing sufficient power to enable level flight at a safe speed, then it may be possible to return to the airfield. Make gentle turns, maintaining height if possible without the airspeed decaying, and choose a route that provides some potential landing sites in case the engine loses further power. It's a judgement call whether you should take advantage of a possible landing site along the way because the off-field landing is almost certainly going to damage the aircraft and possibly injure the occupants. But that must be weighed against the chance of further power loss before reaching the airfield, producing a much more hazardous situation; it is usually considered best to put the aircraft down at the first reasonable site. If there is insufficient power to maintain height then you must set up an off-field landing. Read the article 'Piper Worrier' in the January–February 2003 issue of Flight Safety Australia. 3. If the engine is producing intermittent power it is probably best to use that intermittent availability to get to a position where a glide approach can be made to a reasonable off-airfield site. Intermittent power negates the ability to conduct a controlled approach and could get you into a dangerous situation. So having achieved a position where you can start the final approach then shut down the engine by switching off fuel and ignition or, at least, fully close the throttle. Fully shutting the engine down early means the engine will be cold at touchdown, which reduces fire risk. 7.2.3 En route emergency procedure While en route at an appropriate cruising altitude you must maintain the habit of continually assessing wind velocity at cruising altitude and the best general areas for possible landing sites — taking into account the wind and glide distance and not forgetting to take note of what is right below. If the engine should fail, or give concern, first head directly to that general area at Vbg; or if it is very close then use Vmd and aim to make a spiral descent over that area. Trim to the chosen speed and maintain balanced flight; slip/skid increases drag. If you are more than 2500 feet agl you will have ample time available to make choices and the following procedures may be appropriate: Do the troubleshoot checks described above and configure the aircraft for minimum drag, i.e. flaps and wheels up. Ease the nose down a little when selecting flaps up to avoid stalling the aircraft. Try to stop a windmilling propeller, but if you don't succeed with the first attempt forget it. Change to fully coarse pitch (the minimum rpm position) if the propeller is adjustable in flight. Make a distress or urgency call and, if equipped, set the transponder to squawk 7700. Pick a first choice landing zone: something large, flat and firm, with few obstructions (which allows a circling approach and a multiple choice of landing runs) would be ideal. You will have to consider many factors and combinations thereof; for example, a site that provides a long ground run but which entails a downwind landing compared with a shorter, into wind and downsloping landing path, or an obstructed approach but clear landing path compared to a clear approach but obstructed surface. If you have been caught out in heavily treed hilly country the only options may be to: (a) land in a creek bed; (b) land along a ridge top; or (c) fly along a valley line then turn to land upslope onto the tree tops. In the latter case the airspeed would need to be greater than Vbg to provide sufficient energy to execute the turn and the subsequent flare to follow the upslope without stalling. Whatever alternative is chosen is high risk, but easily avoidable by not overflying such terrain at insufficient height to glide clear. Ground obstructions — stumps, roots, rock outcrops, boulders, termite mounds, ditches, potholes, old farm machinery, fences and power-lines — may not be visible until closer, so select an alternate landing zone nearby in case the first choice proves not so good. ('Single wire earth return' power-lines are near impossible to see — particularly if it's oxidised copper.) You can probably afford to change your choice once, but not twice! If landing in an obviously ploughed field try not to land across the furrows, particularly in a nosewheel aircraft; close to a fence the furrows generally parallel the fence line. If possible, avoid surface water. Estimate your height above the site by reference to the contour lines on your WAC or VNC and the altimeter. Airborne time available is height divided by the known Vbg descent rate, but flight into sinking air will reduce this. Decide on the general approach pattern and aim to fly as near a normal glide approach as possible, starting with the base leg. Do not plan to fly a normal square circuit; rather, plan a descending spiral that keeps you equidistant from the site. Decide on a base leg positioning location and aim to be at this location at a glide approach height that would allow one minute on a nominal base leg and one minute on final; say about 800 feet agl if your Vbg sink rate is 400 fpm. Avoid a long, straight final approach — it allows too much exposure to unfavourable atmospheric conditions, particularly sinking air and turbulence. Depending on height, distance and wind velocity (remembering the friction layer effect on the vertical wind profile) decide an approach to get down to that positioning location so that the landing zone is always in sight and always within easy reach — which allows the surface, the wind and final approach paths to be rechecked. The approach path should be planned starting with the ground run and working back. The approach path can be widened if far too high — otherwise medium S turns, flaps or sideslip might be used to descend to the positioning location, but flaps should be retracted before reaching there. Flaps probably won't be used again until well established on a final approach. In some aircraft S turns are not that effective in getting rid of excess height. If you feel you are in sinking air or battling a headwind, increase airspeed to a better 'penetration' airspeed above Vbg. Start the base leg from the positioning location and adjust the track and the turn onto final to compensate for the wind, height and/or misjudgements. While flying the base leg finalise the intended ground path for the landing run and select an initial aiming point about halfway along it. You may have to plan for a dogleg during the ground roll. Then carry out the final cockpit check, approach and landing as in 'handling the approach' above. The diagram below illustrates an approach pattern allowing multiple choice of final approach and landing run. The wind is estimated to be in the north west quadrant. Path A is the planned approach and landing run from a base leg positioning location, paths B, C and D show alternate paths which either delay or bring forward the turn onto final to cater for height, wind or positioning differences. Paths E and F show the possibilities for a turn onto a landing path if it is required to do so before reaching the base leg positioning point. Mike Valentine, the late RA-Aus Operations Manager, had a few very relevant comments: The turnback part of the (Coping with Emergencies) series is particularly timely in view of the Skyfox accident last October and the Bantam accident three weeks ago, both of which involved engine failures and attempted turnbacks. It is an old problem and seems to be one that won't go away. In view of this, I hope you don't mind if I offer a comment on a particular point in post-engine-failure training. My main background is in gliding (47 years), with about 30 years GA and 7 years ultralight instructing (Drifter, Gazelle, Skyfox) to add to the mixture. In gliding, we had a persistent problem with loss of control following a winch-launch cable-break and attempted turnback, a situation which is directly analagous to the problem which is plaguing us now. Most, if not all, such accidents were fatal. As Operations Director of the Gliding Federation of Australia, I had to try to address this problem and see if we could tame it. Rather than get involved here in a detailed analysis, I will just give you the bare bones of our efforts. In researching accidents of this kind over a 30 year period (world-wide, not just Australia), a couple of common threads emerged. Firstly, in many cases there was never any need to turn back — there was ample strip ahead and all the pilot needed to do was to establish a safe speed, adjust the approach path with spoilers/airbrakes and land ahead. This is a crucial point and is often overlooked. Secondly, and of equal importance, is the fact that, although a pilot may lower the nose after an engine failure, as briefed, the same pilot may not hold that attitude for a while and allow the speed to increase and stabilise. A glider in the full climb phase of a winch-launch is generally a fair bit steeper than an ultralight in the climb attitude, but the principle is no different (nor is the outcome, when the energy runs out). We did the trials in representative types of training glider, from the 400 kg Kookaburra (33 knot stall, 20:1 L/D) to the 590 kg IS-28B2 (35 knot stall, 35:1 L/D) and the results were remarkably consistent. From a full climb attitude at 55 knots IAS, the cable release knob was pulled, simulating a wire-break. As one pilot immediately took recovery action, using strong nose-down stick movement, the other pilot started the stop-watch. From the time the 'wire-break' occurred at 55 knots to the time 55 knots once more appeared on the ASI was a consistent 6 seconds. This is the amount of time needed before a pilot can make any attempt to manoeuvre the glider. In the types of glider we are talking about, 55 knots is about 1.5 Vs and is regarded by the GFA training system as a 'safe speed near the ground'. I have found that the above figures apply equally well to a Drifter. However, with gliders we then went one stage further. We did it because we were dealing with aircraft which were fully approved for spinning. We tried simulating a winch-launch in free flight by diving to 80 or 90 knots and pulling up to an approximate winch-launch angle, then when the speed fell to 60 knots we lowered the nose and immediately applied aileron and rudder to commence a turn. The result was consistent spin departures, not necessarily immediately but certainly before reaching 180 degrees of turn. All this means that lowering the nose after an engine failure is not the complete answer. If a pilot is not taught that the lowering of the nose should be followed by DOING NOTHING, just holding the new attitude and waiting for the speed to stabilise at the new figure before deciding what to do, he/she will not be protected from loss of control. All this led to a change in training emphasis in the GFA training system. (For an expansion of the foregoing read Mike Valentine's article 'The turn-back following engine failure'.) When preparing this module I asked the late Tony Hayes — a very experienced, enthusiastic and highly respected AUF CFI — a few questions. The following was his response: "I do not actually teach engine failures in the traditional sense of yank the power and "What are you going to do now?" type of thing. That is not teaching, it is checking correct response to something already taught. That is a bit of a non-event with my students as I expect the aircraft to be continually positioned so it has an escape route, if it is not so positioned then I work on the area via fundamentals of positioning rather than alarming and depressing demonstrations of why it is wrong! So my actual 'emergency training' happens in separate areas that include circuit planning, speed management, theory and practical glide appreciation. The whole lot revolves around one single concept that I would very much like the AUF to adopt as standard (it is standard in the gliding world) and that is 'safe speed near the ground'! In the theory area (which I do quite early as part of the fundamentals of control) I use the total drag curve rather than the more abstract polar curve. The interaction between parasite and induced drag is quite clear and the most energy efficient airspeed is clearly understood. To this is then superimposed the speed loss from an abrupt power failure and the average reaction time of a pilot at normal flying arousal levels. On a Thruster this is about 7 knots. 48 + 7 = 55 knots (which is also close to the aircraft's normal conditions approach speed). This is the 'safe speed near the ground' and I insist it is present at any time we are at or below normal circuit height. This is effectively an insurance policy. The aircraft may now sustain a total power failure and will automatically start returning to maximum efficient airspeed by itself, while the pilot wakes up, and so conserves height. This also ensures that there can be no loss of control. The alternative is a probable climb on the low speed side of the drag curve with increasing sink rates and decreasing glide angles. More to the point is that diving the aircraft to get airspeed back will dump height alarmingly fast. What I need to get across is a clear concept in the student's mind that the energy level in low-inertia, high-drag machines is equally as critical as positioning. A well positioned aircraft flown at the correct airspeed can recover. If flown too slowly at the point of failure, even though the angles and distance are right, the dive to recover airspeed will put the aircraft too low and may make recovery impossible! Those speed differences are not terribly alarming in themselves — just 5 or 6 knots is all it takes; which is probably one reason GA pilots get into trouble with ultralights. Once in the undershoot situation from a botched recovery then the scene is set for an attempted 'stretch the glide' and the consequent classic stall/spin. That is also important. Actual sink rates are only really apparent near the ground and the pilot is instinctively going to start pulling back to ease sink, still with a substantial amount of turning to do, and flying too slowly in the first place. The next major step after energy management is beginning to develop is a lot of passive instruction on circuit positioning via observation rather than being involved in actual circuit planning. I do a lot of control and direction refinement at a very early stage while flying the standard circuit pattern but not have the student even aware of what a circuit actually is. Once I come to circuit planning I can then quickly establish the reasons for distance/angle relationships for the type being used and the student is already well used to looking at them. Once we arrive at the point that engine failures are normally 'taught' then instead of teaching them, per se, I teach 'glide appreciation'. This validates the circuit pattern positioning. It is fully briefed on a whiteboard and the student is then pre-warned in the air. There is NO surprise element at all! The student then (with a clear mind) soaks in all the clues and retains them. Rather than becoming a sweaty terrified mess with a clear impression there is hardly any time to do anything, I find my students really enjoy putting their skills to use and everything clicks into place. Still not really finished yet though. When teaching circuit re-joins I instill the concept that while the prime interest is how to get down at a strange airfield (and we do take students to other local airfields 10 minutes flying away) they should deliberately do one extra orbit for the express purpose of looking at the 'way out' when they leave. And that, in my book, is the real key to emergencies – total situational awareness and then controlling the situation! Fly defensively (without huge effort but as a consequence of sound training so you do it automatically). Last year one of my students on 3rd solo had a major engine failure on climb out — which was bloody tough luck but underlines that it can happen. He was correctly positioned, at the correct energy level, and recovered back onto the airfield from a cross wind landing — no problems and no further damage! Knowing your aircraft, taking the time to consider conditions and study a strange airfield, having then a pre-prepared 'what if' game plan in advance will all result in pre-made decisions that only have to be refined if something does happen. This will control over 90% of engine failure drama. STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

The first three modules in this "Coping with emergencies" guide deal with the circumstance where: an immediate landing is forced upon the pilot in command because of engine/propeller failure or fuel starvation/exhaustion or carburettor icing the aircraft remains under control, at least up to the initial impact with the terrain, trees or a water surface all efforts are primarily directed to avoid/minimise injury to persons rather than trying to minimise damage to the aircraft or other property. Skill in forced landing approaches is a vital asset that can only be developed, and maintained, by regular practice and self-assessment. There is no economic way for a pilot to practise vehicle control following first impact on rough terrain. However, competence in accurate handling of the aircraft in adverse conditions, at least up to the final stages of the approach, can be achieved by regular simulations of engine failure from all flight states. Low flying training for the final stages of the forced landing approach — where to survive the pilot may have to manoeuvre an aircraft without power at slow speed around trees or under powerlines — is best undertaken with an experienced bush pilot. See the Safety brief: loss of control in low-level turns. There is some element of chance in every emergency landing (Murphy's Law proposes that what can go wrong will go wrong, and at the worst possible time) but being well prepared is by far the most important factor in deciding the outcome. The main constituent of that preparation is for the pilot to know the aircraft and – faced with the situation where there is no option but to put it down immediately — keep cool, maintain command of the aircraft, decide the landing site (if this is an option) and fly the approach by maintaining a suitable flight speed, and touch down at the lowest controllable vertical and horizontal flight speeds with the wings level and the aircraft in a nose-up attitude — even if landing in tree-tops. That is, the pilot must maintain complete control of the flight path, airspeed, sink rate and attitude right up to the point of first impact. A bit of fear is normal — even desirable — but excessive stress may cause the pilot to concentrate on very few features of the situation to the detriment of other equally important features. Panic or acceptance that there is nothing much she or he can do about the situation will not improve the outcome, but applied knowledge will ensure the best possible result. Before continuing with this page I suggest you review the document 'Airmanship, flight discipline and human factors training'. 7.1.1 Know the best lift/drag ratio L/D and the angle of attack The maximum L/D ratio (pronounced "L over D") for light aircraft — a measure of the aerodynamic efficiency — is usually between 6 and 12. However there is a very wide range; that for a powered 'chute is probably about 3 while some of the recreational aircraft designed with wide span, high aspect ratio wings — to provide soaring capability — have much higher maximum L/D. For example, the Alpin TST-3 motor glider achieves an L/D of 33 when the engine is stowed within the fuselage and can achieve a minimum sink rate of only 150 feet per minute. However, when the elastic breaks most powered recreational aircraft exhibit the flight characteristics of a very low-performance glider — or worse. (Surprisingly perhaps, most Boeing and Airbus jet transports have maximum L/D around 17–18; better than their piston-engined predecessors.) Maximum L/D usually occurs at an angle of attack between 4° and 5° or where the CL is around 0.6. — L/Dmax is sometimes termed the glide ratio because for light aircraft it is just about the same ratio as distance covered/height lost in an engine-off glide at the optimum still-air gliding speed. For example, if L/Dmax = 8 then the glide ratio is 8:1 meaning the aircraft might glide a horizontal distance of 8000 feet for each 1000 feet of height lost, in still air with the wings held level. We can use the '1-in-60' rule to calculate the angle of the glide path relative to the horizon, for example L/Dmax = 10 then 60/10 = 6° glide path angle. If the aircraft is maintained in a glide at an airspeed higher or lower than L/Dmax then L/D will be degraded and the glide path will be steeper; for example if L/D is degraded to 8 then 60/8 = 7.5° glide path angle. Because of the slight flattening of the curve around L/Dmax, the aoa — and thus the airspeed that will provide maximum air distance travelled from the potential energy of height — is more akin to a limited range rather than one particular best glide speed. An aoa either side of that top arc of the curve results in higher drag and thus a decrease in L/D and less air distance travelled without power. However, we may also need to glide at a speed that results in the lowest rate of sink (the vertical component of the velocity vector) so providing the longest time in the air from the potential energy of height. The lowest rate of sink occurs at the minimum value of drag × velocity and the corresponding minimum descent airspeed may be around 80% of the L/Dmax speed. So, the aircraft is moving rather slowly and will not cover as much distance as when moving at the best glide speed, but will take a little longer to lose height. See the speed polar diagram in section 1.2. Forces in the glide In a gliding descent, the forces are as shown in the diagram on the left. In the case of a constant-rate descent the weight is exactly balanced by the resultant force of lift and drag. From the dashed parallelogram of forces shown it can be seen that the tangent of the angle of glide equals drag/lift. For example, assuming a glide angle of 10°, from the abridged trigonometrical table the tangent of 10° is 0.176, so the ratio of drag/lift in this case is then 1 : 5.7. (This is a little little more accurate than using the '1-in-60' rule but inconsequential anyway.) Conversely we can say that the angle of glide is dependent on the ratio of lift/drag at the airspeed being flown. The lower that ratio is, then the greater the glide angle — and consequently the greater the rate of sink and the lesser the distance the aircraft will glide from a given height. The rate of sink is the resultant of the gliding angle and the airspeed. Be aware that the aircraft manufacturer's quoted L/Dmax may be overstated and generally will not take into account the considerable drag generated by a windmilling propeller so, for glide ratio purposes, it might be advisable to discount the quoted L/Dmax by maybe 20%. But the best option is to check it yourself. 7.1.2 Know the best glide and minimum descent airspeeds The aoa associated with maximum L/D decides the best engine-off glide speed (Vbg) according to the operating weight of the aircraft. There are two glide speeds that the pilot must know and, more importantly, to also be familiar with the aircraft attitude — in relation to the horizon — associated with those airspeeds, so that when the engine fails you can immediately assume (and continue to hold) the glide attitude without more than occasional reference to the ASI. • Vmp — minimum power — the speed that results in the lowest rate of sink in a power-off glide, providing the longest time in the air from the potential energy of height. The lowest rate of sink occurs at the minimum value of drag × velocity and may be around 80% of Vbg. Vmp is the airspeed used by gliders when utilising the atmospheric uplift from thermals or waves. This is the airspeed to select if you are very close to a favourable landing site with ample height and a little more time to plan the approach would be welcome. It is also the airspeed you should reduce to in the last stage of a forced landing in order to minimise both vertical and horizontal velocities, and thus impact forces. Vmp decreases as the aircraft weight decreases from MTOW, the percentage reduction in Vmp is half the percentage reduction in weight. So, if weight is 10% below MTOW then Vmp is reduced by 5%. Vbg is also reduced in the same way if weight is less than MTOW. • Vbg — the best power-off glide — the CAS that provides minimum drag thus maximum L/D, or glide ratio; consequently this provides greatest straight-line flight (i.e. air) distance available from the potential energy of height. The ratio of airspeed to rate of sink is about the same as the L/D ratio, so if Vbg is 50 knots (5 000 feet per minute) and L/Dmax is 7 then the rate of sink is about 700 fpm. This 'speed polar' diagram is a representative plot of the relationship between rate of sink and airspeed when gliding. Vmp is at the highest point of the curve. Vbg is ascertained by drawing the red line from the zero coordinate intersection tangential to the curve: Vbg is directly above the point of contact. Stall point is shown at Vs1. Much is said about the importance of maintaining the 'best gliding speed' but what is important is to maintain an optimum glide speed; a penetration speed that takes atmospheric conditions into account; for example, sinking air or a headwind. The gliding community refers to this as the speed to fly. The normal recommendation for countering a headwind is to add one third to one half of the estimated wind speed to Vbg, which increases the rate of sink but also increases the ground speed. For a tailwind, deduct one third to one half the estimated wind speed from Vbg, which will reduce both the rate of sink and the groundspeed. Bear in mind that, for safety, it is better to err towards higher rather than lower airspeeds. To illustrate the speed to fly, the polar curve on the left indicates the optimum glide speed when adjusted for headwind, tailwind or sinking air. For a tailwind the starting point on the horizontal scale has been moved a distance to the left corresponding to the tailwind velocity. Consequently the green tangential line contacts the curve at an optimal glide speed that is lower than Vbg with a slightly lower rate of sink. This is the opposite for a headwind — shown by the purple line. For sinking air the starting point on the vertical scale has been moved up a distance corresponding to the vertical velocity of the air. Consequently the pink tangential line contacts the curve at a glide speed higher than Vbg. If you want further explanation of speed polar curves (with excellent diagrams) read this article on glider performance airspeeds. The foregoing does not apply to a powered parachute as the glide speed is normally fixed at the aircraft's designed speed. 7.1.3 Know the effect of a windmilling propeller The angle of attack of a fixed-pitch propeller, and thus its thrust, depends on its pitch, the forward speed of the aircraft and the rotational velocity. Following a non-catastrophic engine failure, the pilot tends to lower the nose so that forward airspeed is maintained while at the same time the rotational velocity of the engine/propeller is winding down. As the forward velocity remains more or less unchanged while the rotational velocity is decreasing, the angle of attack must be continually decreasing. It is possible (depending on the particular PSRU, blade angle etc.) that at some particular rpm, the angle of attack will become negative to the point where the lift component becomes negative (reverses) and the propeller may autorotate; in effect, driving the dead engine as an air pump. This acts as greatly increased aerodynamic drag, which adversely affects the aircraft's L/D ratio and thus glide angles. The parasitic drag (including the 'reversed thrust') is greater than that of a stationary propeller. The engine rotation may cause additional mechanical problems if oil supply is affected. In the diagram, the upper figure shows the forces associated with a section of a propeller blade operating normally. The lower figure shows the forces and the negative aoa associated with the propeller now windmilling at the same forward velocity. Thus both Vbg distance and Vmp time are adversely affected by the extra drag of a windmilling propeller, which creates much more drag than a stopped propeller following engine shut-down. If the forward speed is increased, windmilling will increase. If forward speed is decreased, windmilling will decrease. Thus, the windmilling might be stopped by temporarily reducing airspeed possibly to near stall — so that the reversed thrust is decreased to the point where the engine airpump torque and friction will stop rotation. This is not something that should be attempted without ample height. However, do not attempt to halt a windmilling propeller unless: (1) you have more than ample height to recover from a possible stall; and (2) stopping it will make a significant difference to the distance covered in the glide. Sometimes it may not be possible to stop the windmilling. Never be distracted from the job in hand by trying to stop a two-blade propeller in the horizontal position in order to minimise propeller damage during the landing. Should the PSRU fail in flight, the propeller is thereby disconnected from the engine and may 'freewheel' rather than 'windmill'. A variable-pitch propeller may have a feathering facility, which turns the blades to the minimum drag position (i.e. the blades are more or less aligned fore and aft) and thus stops windmilling when the engine is no longer producing power. Such a feature is not usually fitted to a single-engine aircraft, but a few powered recreational aircraft are designed with very low parasitic drag plus wide span, high aspect ratio wings that provide L/D ratios around 30:1, and thus have excellent soaring capability. Propeller parasitic drag will have a relatively high effect on the performance of such aircraft so they are usually fitted with a feathering propeller. The image at left is from a FAA Special Airworthiness Information Bulletin (please read) and shows the change in equivalent parasite drag for both a windmilling propeller and a stationary propeller at blade angles from fully flat to feathered. It can be seen that, in this particular case, the windmilling propeller produces more drag than the stationary propeller up to blade angles of 18 degrees or so. It can be inferred from the preceding material that the windmilling vs stationary drag characteristics for aircraft/propeller combinations will be subject to considerable variation. 7.1.4 Know the practical glide ratio and terrain footprint For accuracy you should measure (preferably by stop-watch and altimeter) the actual rate of sink achieved at Vbg with the throttle closed (engine idling), and from that you can calculate the practical glide ratio for your aircraft. The practical glide ratio is Vbg (in knots multiplied by 100 to convert to feet per minute) divided by the rate of sink (measured in fpm). For example, the glide ratio when Vbg is 60 knots and actual rate of sink is 750 fpm = 60 × 100/750 = 8; thus in still air that aircraft might glide for a straight line distance of 8000 feet for each 1000 feet of height. These measurements should be taken at MTOW and then, if a two-seater, at the one person-on-board [POB] weight with the reduced Vbg. The airspeed used should really be the TAS but, if the ASI is known to be reasonably accurate, using IAS will err on the side of caution. Also with the engine idling, a fixed-pitch propeller will probably be producing drag rather than thrust, so that too will be closer to the effect of a windmilling propeller. You should also confirm the rate(s) of sink at Vmp. Having established the rates of sink you then know the maximum airborne time available. For example, if the rate of sink at Vbg with one POB is 500 fpm and the engine fails at 1500 feet agl then the absolute maximum airborne time available is three minutes. If failure occurs at 250 feet whilst climbing then time to impact is 30 seconds — but 3 or 4 seconds might elapse before reaction occurs plus 4 or 5 seconds might be needed to establish the safe glide speed. Read the section on conserving energy in the Flight Theory Guide. Following engine failure it is important to be able to judge the available radius of action; i.e. the maximum glide distance in any direction. This distance is dependent on the following factors, each of which involves a considerable degree of uncertainty: the practical glide ratio the topography (e.g. limited directional choice within a valley) the height above suitable landing areas turbulence, eddies and downflow conditions manoeuvring requirements the average wind velocity between current height and the ground. The footprint is shifted downwind; i.e. the into-wind radius of action will be reduced while the downwind radius will be increased. The wind velocity is going to have a greater effect on an aircraft whose Vbg is 45 knots than on another whose Vbg is 65 knots. Atmospheric turbulence, eddies and downflows will all contribute to loss of height. Rising air might reduce the rate of descent. Considering the uncertainties involved (not least being the pilot's ability to judge distance) and particularly should the engine fail at lower heights where time is in short supply, it may be valid to just consider the radius of the footprint as twice the current height — which would encompass all the terrain within a 120° cone and include some allowance for manoeuvring. The cone encompasses all the area contained within a sight-line 30° below the horizon. If you extend your arm and fully spread the fingers and thumb the angular distance between the tips of thumb and little finger is about 20°. There is a drawback, in that total area available from which to select a landing site is considerably reduced; the area encompassed within a radius of 60% of the theoretical glide distance is only about one third of the total area. For powered 'chutes the radius of the footprint might be equivalent to the current height, providing a 90° cone from a sight-line 45° below the horizon. 7.1.5 Know the height lost during manoeuvres Any manoeuvring involved in changing direction(s) will lead to an increased loss of height and thus reduce the footprint. This reduction will be insignificant when high but may be highly significant when low. The increase in height loss during a gliding turn is, of course, dependent on the angle of bank used and the duration of the turn. Properly executed, gently banked turns that only change the heading 15° or so produce a small increase in rate of descent and a slight reduction in the margin between Vbg and stalling speed. Steeply banked turns through 210° will produce a significant increase in rate of descent, and a major reduction in the margin between Vbg and stalling speed. It is height loss per degree turned, rather than sink rate, which is important. So, you should be very aware of the height loss in 30°, 45° and 60° changes of heading because they are representative of the most likely turns executed at low levels. Just because an aircraft has a good glide ratio does not mean it will perform equally well in a turn; it may lose more height in a turn than an aircraft that has a poorer glide ratio. For example, a nice slippery aircraft with a glide ratio of 15 may lose 1000 feet in a 210° turn, whereas a draggy aircraft with a glide ratio of only 8 might lose only 600 feet in a 210° turn. Of course, the radius of turn is greater in the faster, slippery aircraft. Steepening the final descent path If it is necessary to steepen the descent path to make it into a clearing, it is recommended using full flaps and/or a full sideslip, and a sideslipping turn from base. A series of 'S' turns will reduce the forward travel. These techniques are certainly not something tried out for the first time in an actual emergency; they should only be used after adequate instruction and adequate competency has been reached — and maintained. The use of full flaps plus full sideslip may be frowned upon by the aircraft manufacturer, but in an emergency situation use everything available. Except for 'S' turns, these techniques are not available with weight-shift aircraft. For powered 'chutes braking both wings simultaneously will slow the aircraft and increase rate of sink but excessive braking may stall the wing. Please read the 'Safety brief: loss of control in low-level turns' section of the Flight Theory Guide before continuing. 7.1.6 Know the height loss in a turn-back following engine failure If the engine fails soon after take-off the conventional and long-proven wisdom is to, more or less, land straight ahead — provided that course of action is not going to affect others on the ground — for example, put you into a building. If the engine fails well into the climb-out one of the possible options is to turn back and land on the departure field. If the take-off and climb was into wind and a height of perhaps 1500 feet agl had been attained (and the rate of sink is significantly less than the rate of climb) then there would be every reason to turn back and land on that perfectly good airfield. There might be sufficient height to manoeuvre for a crosswind landing rather than a downwind landing. On the other hand, there will be a minimum safe height below which a turn-back for a landing in any direction could clearly not be accomplished. To judge whether a safe turn-back is feasible the pilot must know the air radius of turn and how much height will be lost during the turn-back in that particular aircraft in similar conditions, then double it for the minimum safe height. Such knowledge can only be gained by practising turn-backs at a safe height and measuring the height loss. Turning back to land on, or parallel to, the departure runway requires a turn through maybe 210° onto an intercept path for the extended runway line. At interception a small opposite direction turn may be needed to align with the selected landing path. If the take-off has a crosswind component, the initial turn should be conducted into the crosswind so that it will drift the aircraft back toward the extended runway line and reduce the ground radius of the turn. If the take-off has been downwind then the minimum height for a turn-back would be greatly increased. Any doubt whatsoever — do not turn back. Of course, if you have departed from a large aerodrome rather than a small airstrip then there is ample cleared area available for a landing; there is no need to opt just for a runway. Radius of turn and height loss In a turn-back to land on the departure runway it is important to minimise both the distance the aircraft moves away from the extended line of the runway and the time spent in the turn. The slowest possible speed and the steepest possible bank angle will provide both the smallest radius and the fastest rate of turn. However, these advantages will be more than offset by the following: When the steepest bank angle and slowest speed is applied, the necessary centripetal force for the turn is provided by the extra lift gained by increasing the angle of attack ( or CL) to a very high value. Also, due to the lower airspeed, a larger portion of the total lift is provided by CL rather than V². Consequently the induced drag will increase substantially. When turning, it is not L/D that determines glide performance but rather the ratio to the drag of the vertical component of lift [Lvc] that offsets the normal 1g weight, or Lvc /D. Thus, due to the increase in induced drag, Lvc /D will be less than normal L/D, resulting in an increase in the rate of sink and a steeper glide path. Lvc /D degrades as bank angle in the turn increases. See the diagram 'turn forces and bank angle' and read the text that follows it. The stall speed increases with bank angle, or more correctly with wing loading; see wing loading in a turn. Thus the lowest possible flight speed increases as bank in a gliding turn increases. Any mishandling or turbulence during turns at high bank angles and low speeds may result in a violent wing and nose drop, with substantial loss of height; see 'Safety brief: loss of control in low-level turns'. Choosing the bank angle In some faster aircraft it might be found that the turn-back requires a steep turn, entered at a safe airspeed (e.g. 1.2 × Vsturn), where the wings are slightly unloaded by allowing the nose to lower a little further throughout the turn. Then, having levelled the wings, convert any airspeed gained into saving altitude by holding back pressure until the airspeed again nears the target glide speed. The bank angle usually recommended is 45°, because at that angle the lift force generated by the wing is equally distributed between weight and centripetal force, although the Vsturn will be increased to about 1.2 × Vs1. Thus the safe airspeed would be 1.2 × 1.2 × Vs1 = 1.44 Vs1. (The speed 1.5 Vs1 is usually accepted as a 'safe speed near the ground' for gentle manoeuvres.) If the aircraft has a high wing loading, the sink rate in a steep turn may be excessive. Refer to 'turn forces and bank angle'. For aircraft at the lower end of the performance spectrum it may be found that a 20° to 25° bank angle provides a good compromise, with an appreciable direction change and a reasonable sink rate. There may be other techniques for an aircraft fitted with high lift devices. All of this indicates that performance will vary widely, and you must know your aircraft and establish its safe turn-back performance under varying conditions — otherwise don't turn back! More turn-back discussion can be read in 'The turn back: possible or impossible — or just unwise?' STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

Tales are legion of aviators who rose to a mighty challenge. But those annals are incomplete unless you include the inspirational stories of a courageous cadre of contemporary fliers known as the Able Flight pilots. Able Flight, based in Chapel Hill, North Carolina, is a charitable organization founded in 2006 by nonprofit executive and aviation media figure Charles Stites “to offer people with disabilities a unique way to challenge themselves through flight and aviation career training, and by doing so, to gain greater self-confidence and self-reliance.” As Able Flight’s executive director, Stites designed a scholarship program to make that challenge available to people with disabilities by offering joint flight training courses with Purdue University in West Lafayette, Indiana, and Ohio State University in Columbus, Ohio. The Able Flight class of 2020 consisted of 10 individuals from around the United States—some of whose long-awaited opportunities to fly have been further complicated by an unforeseen adversary: the coronavirus pandemic. As the nation celebrated the thirtieth anniversary of the signing of the Americans with Disabilities Act in July, we checked in with past graduates of Able Flight’s scholarship program in hopes of hearing a shot of news from aviation’s front lines and some words of inspiration to share with others who may be trying to map out life’s plan in light of a life-changing event. We were not disappointed. Sean ODonnell of Pennsylvania and Justin Falls of North Carolina are Able Flight alumni who earned their pilot certificates and are forging into the future—two adaptive-aviation pioneers whose efforts to fulfill their dreams have blazed a trail for others to follow. Sean ODonnell, Class of 2007 Any FBO or flight instructor should pay attention and probably take notes when ODonnell, who took his Able Flight training in 2007, talks about giving a passenger a ride in his two-place tandem light-sport pusher-prop-driven Sky Arrow with adaptive hand controls—because what he is describing is the perfect introductory flight. Not just the route, the length of the flight, and the sightseeing selections he uses—the intro starts on the ground and covers all the bases in an easy-to-process presentation to make the passenger feel involved and at ease. ODonnell gauges how much interest the passenger has in the nitty-gritty, and if it seems appropriate, he will demonstrate some mild maneuvers and perhaps cap the flight with a power-off landing. He’s always on the lookout for negative small-airplane myths to dispel—and when he spots one, he is “more than happy to engage that person,” he said, adding, “All fear stems from lack of knowledge.” ODonnell was the second Able Flight scholarship award recipient and the second recipient to earn a pilot certificate. For many years he worked as the director of distance learning education at his alma mater, Villanova University, where he also created an award-winning distance learning program (making him an expert in a field many individuals and institutions are discovering on the fly these days because of the pandemic). ODonnell, who as a high school senior had suffered a paralyzing injury when a car pulled out in front of his motorcycle, also founded Philly Sport Pilot, a training facility for sport pilots that included serving people with disabilities. “Before COVID, [distance learning] was a debate,” he said, noting that much of the know-how now urgently being sought by institutions large and small was known in the 1990s, long before distance learning had overcome the considerable resistance that has still not entirely disappeared. “Now everyone is making the shift,” added ODonnell, who now works in the software industry as a product manager, having “dabbled” in the field for years. He continues to consult with numerous universities on distance learning concepts. “It’s not flying but it’s great,” he said, confiding that he harbors hope of one day having the opportunity to “travel and promote aviation in any way I can.” It will be aviation’s gain when he does. Justin Falls, Class of 2016 Falls says it was worth the time it took to tweak the hand-control modifications of his Zenith 750 light sport airplane now that he can make slick landings like this one in Jefferson City, Missouri, on a cross-country flight. But there’s something Falls likes even more about the modified factory-built LSA he bought from Zenith owner Sebastien Heintz in 2018: Now other people with disabilities will be able to train to become pilots in his airplane. The Able Flight Class of 2016 pilot became quadriplegic as a result of a neck injury when he was in college. As a pilot he appreciates that he never has to take his hands off the controls during flight thanks to a working collaboration he forged with Zenith to design and refine the control system. He also likes the easy access the aircraft provides him, and he values its capacity to transport his wheelchair to his destinations when he launches from his home base in at Lincolnton-Lincoln County Regional Airport. Inspired by the access to aviation that the Able Flight program provides, it is especially meaningful to him that other student pilots will be able to receive dual instruction in the airplane, following two participants who have done so to become sport pilots. “I wanted to continue that,” he said. Flying was “nowhere on my radar” when Falls was recovering from his injury. But as he began to look into how to get involved in adaptive sports—now he is a competitor in wheelchair rugby and tennis—“I realized that there are a lot more things that you can do in an adaptive capacity,” he said. Having grown up near a general aviation airport and attending many airshows there, the idea of flying came to mind. He found videos online of “guys flying with hand controls,” and his web searches brought him into contact with Able Flight. The big moment came in 2016 when he became an Able Flight scholarship recipient about the same time he began to put his academic endeavors to work as a pharmacist at the Frye Regional Medical Center in Hickory, North Carolina. The medical center encouraged him to fly and gave him time off to get his pilot certificate. “That year alone, the job, flying—I was on cloud nine, just like another level,” he said. “I felt like I could do anything.” Flying for fun continues as time permits for the busy pharmacist, who as a health-services professional sometimes endures hardships imposed on the health care sector by the coronavirus pandemic, including coping with shortages of medications for patients. Falls recently took a passenger on a flight to Gilliam-McConnell Airfield in Carthage to enjoy open-air barbecue at an airport restaurant. He is discovering, as all pilots do, that each flight delivers a unique lesson. On the Carthage run it was experiencing unusual in-flight visibility conditions caused by a Saharan dust plume that had been blown across the Atlantic Ocean to envelop parts of the east coast in late June. Falls encourages any person with disabilities who longs to fly to check out the success stories of pilots with a wide range of disabilities on the Able Flight website, and he thinks most viewers will find the results promising—and perhaps even prompt a scholarship application. Next, he said, a prospective pilot should make inquiry at the local airport and take action to go up with an instructor on an introductory flight. Get a clear idea of what is involved in learning to fly, he said, because although it is fun, “this is hard work.” It may take time to locate or develop an adaptive aircraft that suits an individual’s unique needs—in his own experience, getting the hand controls ironed out took two years—but patience and diligence can pay off. Then, if after laying the groundwork everything looks right, “Go for it, absolutely, 100 percent,” he said.

Wingsuit flying certainly captured folks' attention when it first hit the mainstream around the turn of the millennium, sparking a wave of GoPro and Red Bull videos. Human flight had never been so personal or so physical as these intrepid maniacs half-fell, half glided through rocky gaps and mountain passes like turbocharged flying squirrels. The name of the game quickly became to see how close you could fly to things without hitting them, in search of the ultimate rush and the biggest view counts. But these devices were limited in that your only source of acceleration was gravity itself, and your flight profile could only ever take you downward. No longer. Stuntman Peter Salzmann had been thinking for years about how to add some sustainable propulsion and climbing ability to the wingsuit experience, and he hooked up with creative consultants at BMW's Designworks studio to create a chest-mounted set of electric impellers and a wingsuit that would work with them. At first, he wanted to mount the props in a backpack arrangement, in longer tubes capable of generating more thrust. But the most advantageous airflow would be in front of him, and he found the initial design too heavy. So a chest mounted system it was, with two 5-inch (13-cm), 25,000 rpm impellers in a relatively compact but still pretty chunky unit that has a bit of a submarine kind of look to it. The wingsuit was designed to incorporate air inlets for the propulsion system. There's an on/off switch, a two-finger throttle and a kind of steering facility, as well as a cutoff switch for emergencies. Otherwise, she's even more of a physical thing to fly than a regular wingsuit; you need plenty of core and limb strength to fight the wind and control your motion in the air. The props put out a relatively modest combined 15 kW (20 hp) for around five minutes, but the results are pretty epic; a regular wingsuit's most horizontal glide ratio drops around a meter for every three meters traveled horizontally, and speed tops out around 100 km/h (62 mph), but when Salzmann hits the electric boost, he can hit speeds over 300 km/h (186 mph), and actually gain altitude to fly upwards instead of constantly dropping. After wind tunnel testing, both in BMW's more auto-focused facilities and in a specialized wingsuiting wind tunnel in Stockholm, and around 30 test jumps, it was time for a public demonstration. The initial plan was to demonstrate the suit's climbing capability by taking it to Busan, Korea, and flying over a group of three skyscrapers, in which the final one was much higher than the first two. COVID-19 put paid to that aspiration, so Salzmann settled for something prettier and closer to home, lining up the Del Brüder peaks in the Hohe Tauern mountain range, part of the Austrian alps. Salzmann and a pair of buddies kitted out with regular wingsuits went up to 10,000 feet (3,050 m) in a chopper, counted down, and jumped. The others are there to act as a reference point, and the three hold formation until Salzmann hits the juice and blasts forward. Where his friends have to split off and fly around the final mountain peak, the electric wingsuit allows him to accelerate up and over it. It's not going to blow Yves Rossy's skirt up; the Swiss "Jetman" has four incredibly powerful jet turbine engines on his extraordinary full carbon jetwing design, which allow him to blast off vertically from the ground with computer-controlled stabilization, and shoot vertically upwards like a rocket as well as swooping and soaring like a 400-km/h (250-mph) eagle. But jet turbines are insanely expensive, and so noisy that they rattle windowpanes from miles away. The average wingsuit pilot's chances of ever flying one are very limited. Salzmann's design, on the other hand, looks much more promising. The electric wingsuit has had the full BMW design touch applied to it; it looks very nicely put together, and, dare we say, much more like a product than a prototype. Nobody's saying anything about these things being for sale yet, either now or into the future, but a small electric propulsion unit is not going to cost jet turbine money, and it's hard to imagine an adrenaline-fueled wingsuit pilot in the world that wouldn't be interested in getting that little bit closer to the Icarus dream of soaring through the sky, rising and gliding at will. Indeed, the main issue may turn out to be whether a company like BMW wants its logo on a product that potentially makes its owners go splat. It's one thing to be making promo videos for world-first innovations like this, and another altogether to release these tools into the hands of extreme sportsfolk where the difference between successful and unsuccessful flights can be so gruesome. Things have come a long way since the first "wing suit" flight – a brief and messily fatal leap off the Eiffel tower by Franz Reichelt in 1912 – but wingsuity types don't seem to be able to get their pulses racing without cutting things really fine. Still, I think we can all rest assured that we'll see more of Salzmann and this device as things develop, and that consumer-grade electric wingsuits will soon be a thing, and that this public debut is a significant moment in personal flight and extreme sports. Enjoy the video below.

Organiser calls chance to land at big international hub ‘a childhood dream’ The scarcity of commercial flights landing at Sydney airport has been a disaster for airlines and workers, but for hobby pilots the pandemic has provided the opportunity of a lifetime. The quieter than usual runways mean private pilots have been given the chance to land at the international airport for the first time. When the Sydney Flight College club captain, Tim Lindley, put out a call he received an overwhelming response. He eventually organised for 14 light aircraft to fly into Sydney airport on Sunday with 40 people involved. “For a lot of the pilots involved, including myself, it was a childhood dream to land in a big international airport like that – like the airliners,” Lindley said. His group took off from Bankstown airport, where many private pilots usually fly from, came in over Sutherland and landed at Sydney airport. Although the runways weren’t busy, Lindley and his crew still had to navigate some huge aircraft. “Lots of the pilots had passenger jets waiting on the side of the runway, which must have been really funny to watch, with these small little planes coming in,” he said. “When I was taxiing, I had a Jetstar Airbus in front of me and an Air China 767 behind us, and we were all waiting for another one of the club’s aircraft to land.” Lindley – who was flying a Cessna 182 with three passengers on board – had worked with airport staff to make sure the pilots knew what to expect and how to approach an airport of such size. “Coming in to land at an airport like that … there are lots of optical illusions because it’s such a long runway, and because it’s so wide,” he said. “The thing is, the airport is designed to have the pilot sitting 30 feet in the air, so we’re sitting in a little aircraft, and you’re sitting maybe one foot off the ground, none of the signs are aimed at you, so it’s actually incredibly disorientating.” A hobby pilot prepares to land his light aircraft at the quieter than usual Sydney airport on Sunday. Photograph: Lorenzo Hariman The main runway stretches for nearly 4km – far longer than smaller aircraft need to land. Australia’s largest airport usually has a crammed schedule, making it almost impossible for private pilots and hobbyists to land. Some private planes have landed there in the past, but the airport’s airfield operations supervisor, Nigel Coghlan, said the pandemic had allowed the runways to be opened up like never before. “As our airfield is much quieter than usual due to Covid, we’ve been able to review each request and grant access, which for a lot of hobby pilots is a once in a lifetime opportunity,” Coghlan said. “We’ve been able to open up conversations with light aircraft pilots because our airspace is much quieter than usual.” The airport is experiencing 60-90 plane movements a day at present, a huge drop from the 800-900 that ordinarily use the runways. That “significant drop” has had a huge impact on the aviation industry, Coghlan said. For Lindley, it was about making the most of a difficult period. “It was really about turning lemons into lemonade,” he said. “It’s such a horrible situation with Covid, and it’s a really challenging time in aviation, and I just wanted to turn that into something a little bit positive, to keep people flying and keep their dreams alive.” Pilots had to submit a flight plan and book a landing spot. Coghlan and his team then had to adapt to the smaller aircraft and guide them in unfamiliar territory. “We’re certainly not used to the smaller aircraft, so they really keep us on our toes when they arrive,” he said. “Being smaller means they’re harder to see than the jets and turboprops and they don’t make as much noise. It creates a positive challenge for all of us on the airfield.” For some of the hobbyists, he acknowledged, “we’re literally making their dreams come true”.

When the light sport aircraft idea first broke ground 20 years ago, the idea was a new class of airplanes bridging between so-called “fat ultralights” and standard-category airplanes whose inflated prices made them unaffordable save for the wealthy few. Two decades later, has the experiment paid off? Yes, but with some qualifications. Light sport airplanes were supposed to be simpler to build and certify— they are—and although the original design brief didn’t specifically say so, it was assumed they would be cheaper to buy. They are that, too. But only relative to new, standard-category airplanes and not compared to any of dozens of legacy two- and four-place airframes with similar or greater capability. So, are LSAs cheaper to own than equivalent legacy airplanes? The answer depends on how you crunch the numbers, but if investment costs are tallied, the answer is no. If operating costs alone are considered, light sport airplanes look attractive against both legacy airplanes and definitely any new standard-category aircraft. Compared To What? Why do people buy light sport airplanes? Probably for exactly the purpose they were intended: Remaining in the flying game with modern airframes with modest performance. Although light sports haven’t been a runaway sales success, the total population of aircraft totals about 4000 airframes, according to www. bydanjohnson.com, which tracks production by models. And don’t look now, but sales of LSAs have recently accounted for between 19 and 21 percent of all piston aircraft sales, according to Johnson’s site and GAMA reports. (That includes ELSA kits, but not gyroplanes.) In 2018 and 2019, the LSA segment registered 219 and 233 aircraft respectively, against total GA piston sales of 1137 and 1324 for the same years, according to GAMA. Those totals include 80-plus airframes from the five manufacturers who are GAMA members: Icon, Pipistrel, Tecnam, CubCrafters and Flight Design. The rest are from non-GAMA companies. Johnson warns because of fuzziness in the data, a precise market-share calculation is elusive. Still, LSAs have measurable presence. The venerable Aeronca 7AC Champ is the hands-down best value in legacy LSAs. And good luck putting a CTLS on skis, as owner Pete Burns has done with his Champ. As we’ve reported before, the LSA market is nothing if not lousy with variety. Dan Johnson’s site counts a dozen manufacturers delivering modest volume. Recent market leaders include Zenith, Kitfox, Van’s, Rans, Pipistrel, Icon and Progressive Aerodyne. Flight Design once topped the market, but it’s now clawing back after financial retrenchment. The typical price of a well-equipped LSA—and few buyers skimp on options—is north of $150,000. For our survey group of a dozen owners, the average price was $117,000, but some of the owners bought used airframes. The high price was $175,000. At this juncture, you can slice the loaf two ways by asking what else $150,000 buys or what would an equivalent two-place airplane cost? This produces radically different outcomes. The 150 large would get you a nice late 1980s Mooney, a late 1990s Skylane or an early 2000s Skyhawk, for example. But it appears that buyers shopping LSAs don’t engage in that kind of calculus. They aren’t looking for price-value, exactly, as much as they are simple, easy-to-fly and easy-to-maintain airframes. Many of them are stepping down from more capable aircraft, including piston twins and even turbines. If cheap is the overarching driver in a two-place airplane, the pickings, while not necessarily slim, are vintage, not to put too delicate a point on it. Consider the last model year of the Cessna 152, 1986. Find them in the low- to mid-$40s to as much as $90,000 for a fully restored airframe. Piper’s two-place trainer, the Tomahawk, goes for a song and a parsimonious one at that: $14,000 to $20,000. The Beech Skipper is another possibility that’s a better flyer for around $16,000. And don’t forget the venerable forerunner of the 150, the 120/140 series. Again, prices for these are in the $25,000 to $35,000 range and some have been nicely restored. There’s also a passel of Pipers to pick from, including the J-3, the Super Cub, the Colt and even the Tri-Pacer if you want a backseat. The immediate downside of these is most are standard-category airplanes and thus require the pilot to have a medical. While some thought BasicMed would decimate the light sport segment because pilots would have no worries about the medical issue, this is evidently not the case or at least is far less influential than we imagined. Several owners told us medical certification—or lack thereof—was a consideration in their purchase of an LSA and that BasicMed didn’t change that. Cost Of Money Van’s RV-12 has become a popular E/S-LSA. Ian Heritch’s example has flown coast to coast and was purchased new three years ago. For our email survey of a dozen LSA owners, we asked about purchase price, insurance, fuel and hangarage costs and maintenance. But first, let’s dispense with the largish pachyderm on the premises: depreciation. This is always a slippery number, even for legacy airplanes and it’s all but impossible to calculate a meaningful average. For one, there aren’t enough sales of these airplanes to establish take-it-to-the-bank trends and for another, ultimate value is determined between the buyer and seller the moment the check is signed. But let’s do some for instances. A CubCrafters Carbon Cub bought new in 2015 for $200,000 depreciated to $165,000 four years later or about 18 percent. Call it $9,000 per year. A Flight Design CTLS retailed for $156,500 in 2015 and now, according to Aircraft Bluebook, it’s typically worth about $115,000 for a depreciation of 27 percent or about $10,000 a year. For a longer timeline, consider Tecnam’s P92 Super Echo. It sold new in 2008 for $115,000 and now retails for about $45,000 for a loss of 61 percent value over 11 years or a decline of $6000 a year. These exact values matter less than the fact that newer airframes will depreciate more than older ones will and it’s a real part of the cost of ownership. Older airplanes, say ragwings like Cubs and Champs or vintage Cessna 150/152s, will depreciate less or not at all. Some even appreciate slightly with market swings. Although many owners seem to purchase airplanes without financing, if a loan is required, the cost of that money should be added to depreciation. Tallying It Up Apart from purchase, depreciation and cost of money, the next largest expenses will be either fuel or insurance, according to our survey. That’s dependent on how much you fly, but the owners we surveyed averaged about 70 hours a year and reported an average of $19 an hour for fuel. Using those numbers, fuel totals about $1330 a year. Much of the LSA fleet is powered by Rotax 912-series engines and although they’ll burn 100LL, they’re a lot happier on unleaded mogas. Many owners use that or, often, a mix. This may have a slight advantage in conferring better aging of the fuel, but even 50 hours a year on mogas is unlikely to cause varnish or deposit issues. Rotax recommends a shorter oil change interval when avgas is used: 25 hours if 100LL is used 50 percent of the time versus 100 hours if unleaded fuels are burned. Most owners stick to 50 hours or less for oil changes, whether flying with a Rotax engine or a legacy Lycoming or Continental. Insurance is becoming a sticky point for owners and with the market hardening, it may be getting stickier yet. The average insurance cost among our dozen-owner survey was $1534. The highest was $3200 on a recent vintage Flight Design CTLS, the lowest $909 for an RV-12. Straight-up comparisons against legacy two-seaters are difficult because insurance on a Cub, a Champ or a Cessna 152 can cost just as much, depending on hull value. The bigger driver may be pilot age. As the market hardens, more insurers are raising premiums on older pilots, if they’re not turning them down entirely. “Insurance has been $1100 a year. For the May 2020 renewal, it will be $1700 a year for a hull insured at $89,000. Time to lower the value,” said Flight Design owner John Horn. At these prices, more owners may be considering self-insuring the hull or entirely. Operating Costs Bill Spencer in his Legend Cub. “The LSA rules have allowed me to own and fly beautiful and well-equipped new airplanes.” If anything is a constant in aviation, it’s that’s bigger, faster airplanes burn through money at a faster rate and the near-ruinous annual is always in the offing. In that respect, legacy two-seaters and LSAs are definitely less money hungry, starting with annuals. Owners in our survey reported the average cost of an annual as $529. That requires amplification, however. Two of the owners in our survey group invested in a two-week course for the Light Sport Repairman Maintenance rating, which allows them to repair their own airplanes, including annual inspections. While IAs can’t be fashioned in two weeks, we think this rating is a terrific idea. It costs up to $5000, but the real value is in engaging an owner in understanding the airplane, inspecting it for faults and repairing it when needed. In our view, that’s not just a cost benefit, but a safety enhancer, too. We asked owners if they had experienced any unusual maintenance issues, costs or problems that hadn’t been expected. None had, and all said the maintenance expenses were about what they expected or a little less. None had any complaints about the Rotax engines that power most of these aircraft. There were no reports of maintenance disasters such as corroded spars or major, timed-out parts. What to compare the Rotax to? We can think of only three possibilities: the Continental A-65 found in Cubs and Champs, Lycoming’s O-235 or the Continental O-200, the lightened version of which is used in a few LSAs. The A-65 is on par with the Rotax for fuel burn, but the O-200 and O-235 are a tad thirstier. All three legacy engines are stone-age throwbacks compared to the Rotax, which has electronic ignition. The 912 iS also has fuel injection. The Rotax is cheaper to overhaul. Dean Vogel at U.S. Rotax distributor Lockwood Aviation says the base overhaul price for a 912 ULS is $13,500, assuming a good core. A factory-new engine costs $19,000. The price delta between a new O-200 and an overhaul is larger and you can’t even get a new A-65, although new cylinders are available. The A-65 remains a serviceable choice, but overhauls are in the $15,000 to $18,000 range. Vogel told us Lockwood advises owners of high-time or high-use aircraft to make the overhaul decision 500 or so hours before TBO. He said the engine can be sold on the used market to a homebuilder and the owner can then buy a factory-new engine, applying the considerable proceeds from the used engine sale. Tying it Up Owners who bought new or recent used light sport airplanes seem satisfied with the purchase and operating costs and report no unpleasant surprises, nor regrets in having made the purchase. These owners were a mix of step-down buyers and bucket listers who always wanted to own an airplane and found the ability to do that in an LSA. “From my experience, LSA has become an accepted and somewhat vigorous part of U.S. general aviation,” said RV-12 owner Ian Heritch. “Wherever I go, I get only compliments and questions from onlookers. I have experienced no hostility for operating in the airspace system. While not the super-robust category that many were unwisely expecting, LSA has safely, smoothly and successfully joined the U.S. aviation family,” he adds. “If you want to keep flying, this is the way to go,” adds CTLS owner Ben Short. But the design brief is to determine whether an LSA is cheaper to own and operate. It can be, if it’s bought right. If you don’t factor in the steep depreciation a new aircraft suffers the day after you take delivery, then new and used are comparable. “Bought right” to us means an airframe that’s had the painful part of the depreciation already squeezed out of it. That means at least five years old, but 10 would be better. There are bargains out there. A 2006 Flight Design CTSW is still perfectly serviceable and supported with a typical values in the mid-50s. Newer ones with glass panels aren’t much more. Even at the higher purchase price, ownership costs would be competitive with a legacy two-seater. If you can’t find or afford a hangar, a glass airplane can live outside or in a shade hangar, which a ragwing— vintage or newer—cannot. Speaking of ragwings, the Cubstyle airplanes appear to hold value better than other LSAs. Specifically, a five-year-old Carbon Cub still commands $165,000, according to Bluebook. Arch competitor Legend shows similar price stability, making them a good choice if short-term ownership is envisioned. You can get in and out without losing much. That’s true of all of the legacy models that qualify for LSA operation, too. They’ve reached rock-bottom value and aren’t likely to depreciate much at all, if that’s a buying consideration. Some parts for older aircraft are hard to come by, but owners tell us they remain supportable. Just make sure the pre-buy filters out expensive gotchas.

6.7.1 Defining turbulence and wind shear Turbulence It is usual to classify all the changes in atmospheric motion that significantly disturb aircraft flight as turbulence, but in some wind shear events there may be no air turbulence involved. It is difficult to define the degree of turbulence or the load effects of shear in a way that is meaningful to a recreational and sport aviation pilot. Measuring by the airflow velocity change or the gust velocity measured in feet per second doesn't really enable the pilot to judge how turbulent the conditions are in their circumstances, particularly so if the instrument panel is not equipped with an accelerometer or variometer. The following is based on an old ICAO turbulence scale which, though classifying by the induced positive or negative accelerations (only as measured near the aircraft cg), does provide a descriptive definition of sorts that is appropriate for three-axis aircraft, but perhaps not so meaningful for flexible-wing weight-shift aircraft (powered or unpowered) and certainly not meaningful for powered-parachutes or paragliders. Very low — below 0.05g; light pitch, yaw and roll oscillations are experienced. Low — 0.05 to 0.2g; aircraft might experience light to moderate 'chop', i.e. slight, rapid, rhythmic bumps and oscillations but any without significant changes in altitude or attitude. Like driving a boat through a choppy sea. Also known as 'cobblestoning' — like driving at moderate speed on a corrugated gravel road. Moderate — 0.2 to 0.5g; turbulence is becoming significant and the ride produces strong, intermittent, uncomfortable jolts with attitude upsets and indicated airspeed variations, but the aircraft remains in control. The occupants' heads may hit the cockpit roof structure if the clearance is small or the harness is not tight enough. Severe — 0.5 to 1.5g; the aircraft handling in all axes is made difficult but not dangerous except at lower alitudes — if occupants and objects properly secured.There are large, abrupt changes in altitude and attitude, and significant variations in indicated airspeed. Cockpit instruments are difficult to read. Very severe — above 1.5g; the aircraft is violently tossed about, with extreme handling difficulty. Aircraft may be out of control for short periods. Structural damage is possible. The wake vortices from aeroplanes and helicopters add another form of turbulence that is extremely hazardous to all recreational aircraft, particularly because of the strong rotational effects that lead to sudden height loss. Such vortices must be anticipated and avoided. Wind shear In aviation terms, wind shear is a sudden but sustained "variation in wind along the flight path of a pattern, intensity and duration, that displaces the aircraft abruptly from its intended path and sufficiently that substantial and timely control action is needed". Wind shear is probably the greatest hazard to flight at low levels in visual meteorological conditions, but its effect is short-lived. Displacement in the flight path is initiated by a substantial change in lift generation associated with the aircraft's inertia (see Note 1 following). The shearing action between air layers with substantially differing velocities — or vertical gusts and their surrounds — may also induce strong turbulent eddies or breaking waves at the shearing level or interface. Note: inertia is the property of resisting any change in motion, or continuing in the same state of rest or state of motion relative to the Earth's cg. The mass of a body is a measure of its inertia; i.e. its resistance to being accelerated or decelerated by an applied force (such as a change in aerodynamic lift) increases with mass. An aircraft in flight is 'airborne' and its true airspeed is relative to the surrounding air, not the Earth's surface. However, when the aircraft encounters a sudden change in the ambient air energy/velocity — even just a transient gust, horizontal or vertical — inertia comes into play and momentarily maintains the aircraft motion relative to the Earth or — more correctly — relative to space. This changes aoa and airspeed, and imparts other forces (e.g. drag and pitching moments) to the aircraft. A heavier aircraft has more inertia than a lighter one, so is more resistant to irregular, random displacement forces — atmospheric turbulence. The fact that inertia momentarily overrides the physics of aerodynamics is sometimes a cause of confusion. As long as an aircraft's mass remains unchanged so will its inertia whether it is at rest or moving; i.e. motion or pulling g has absolutely no effect on an aircraft's inertia but speed does affect momentum, which is mass (or inertia) × velocity. Wind shear can be induced by the terrain, constructed obstructions, passage of cold fronts, convective downbursts, thermals, temperature inversions, low-level jets and other sources; all of which will be described later. The closer to the surface that the shear occurs the more hazardous for aircraft — and particularly so for very light aircraft. For an aircraft taking off, landing or going around, the shear may be large enough and rapid enough to exceed the airspeed safety margin and the aircraft's capability to accelerate or climb; or the pilot just may not be able to recover an uncommanded roll due to a crosswind gust, before a ground strike occurs. The shear is the rate of change of wind speed and/or direction experienced by the aircraft, Such events tend to be classified as 'vertical' or 'horizontal' shear, though many, perhaps most, shear encounters are a combination of both. There is a third classification — 'vertical gust' shear — which has the greatest potential to produce extreme structural loads and which we will examine first. 6.7.2 Vertical gust shear Gust categorisation Vertical gust shear, chiefly associated with updrafts and downdrafts, is the change in the predominantly vertical air motion with horizontal distance flown. Thermals can produce very severe updraft shear when flying in the unstable, high-temperature superadiabatic boundary layer conditions endemic to inland Australia, though their vertical speed near the surface may be relatively low but accelerating with height. There is a noticeable transition gradient between the surrounding air and a well-ordered updraft/downdraft core; also the ascending/descending column tends to entrain some surrounding air, creating a turbulent interface around it. It is possible that a cruising aircraft suddenly encounters an area of substantial vertical motion. The sudden entry (an aircraft cruising at just 60 knots is moving at 100 feet per second) into such a strong vertical gust is a hazardous form of shear. Apart from fast-rising thermals, such events are also associated with downdrafts from large, vertically developed convective clouds. Note: the categorisation of vertical gusts is not the same as the usual atmospheric turbulence. The meteorological categories for wind gusts in general (as measured with an anemometer) are: Category 1: weak — ≥ 5 m/s to <10 m/s Category 2: moderate — ≥ 10 m/s to <15 m/s Category 3: strong — ≥ 15 m/s to <25 m/s Category 4: severe — ≥ 25 m/s The meteorological categorisation restated for vertical gust measurement might be: Weak — ≥ 16 fps to <25 fps Moderate to strong — ≥ 25 fps to <50 fps Strong to severe — ≥ 50 fps to <80 fps Extreme — ≥ 80 fps (or 66 fps [20 m/s] might be used) Speed conversion table (values rounded) Metres per second Feet per second Feet per minute Knots 5 m/s 16 fps 1000 fpm 10 7.5 m/s 25 fps 1500 fpm 15 10 m/s 33 fps 2000 fpm 20 15 m/s 50 fps 3000 fpm 30 20 m/s 66 fps 4000 fpm 40 25 m/s 80 fps 5000 fpm 50 It is probable that 60% of vertical gusts associated with thunderstorms have velocities of 10 fps or less, while 35% are in the 10 to 25 fps range. An encounter with a gust over 50 fps would be rare — but of course it does happen and always when you don't expect it; see this recreational pilot's report. Vertical gust shear effects On entering a gust, inertia will momentarily maintain the aircraft's flight path relative to the Earth's cg. For a very short period the 'effective airstream' around the wings will no longer be aligned with the flight path but will have acquired a vertical component. So, the aircraft's effective angle of attack [aoa] must alter — with a consequent change in the lift and drag coefficients, plus a change in wing loading. The combination of updraft/downdraft velocity with the aircraft's forward speed also produces a change in the effective airspeed relative to the wing, which also affects the wing loading. But in purely vertical gust encounters, this is very slight in comparison to the aoa change and can be ignored. The reverse happens in encounters with purely horizontal gusts — the aoa change is slight in comparison to effective airspeed change. Most turbulence or shear encounters incorporate vertical, horizontal and lateral components, and will affect aoa, airspeed and attitude. Table 7.1 shows the approximate addition to, or subtraction from, the original aoa experienced by four imaginary aircraft each in level flight at a cruise speed where the aoa is 4° and encountering vertical updrafts or downdrafts of the speed shown. Such angles are readily calculated using the 1-in-60 rule; i.e. angular change = gust speed/aircraft speed × 60. The values in red indicate where the stalling aoa, presumed to be 16°, would be exceeded and thus any gust-induced loading is alleviated (with a momentary delay due the aircraft inertia), but the stall indication is applicable only to updrafts and not downdrafts. I have used these reasonably close approximations: (a) to convert knots to metres per second, divide by 2; (b) to convert knots to feet per minute, multiply by 100; (c) to convert feet per minute to metres per second, divide by 200. Table 7.1: increment or decrement in aoa due to vertical gusts encountered at the cruising airspeeds shown and aoa 4° Vertical component of air current 60 knots (6000 fpm) 75 knots (7500 fpm) 100 knots (10 000 fpm) 120 knots (12 000 fpm) 500 fpm (8 fps) 5° 4° 3° 2.5° 1000 fpm (17 fps) 10° 8° 6° 5° 1500 fpm (25 fps) 15° 12° 9° 7.5° 1750 fpm (29 fps) 17.5° 14° 10.5° 9° 2000 fpm (33 fps) 20° 16° 12° 10° Encounter with an updraft For example let's look at a two-seat aeroplane (we'll call it 'Model A') with a wing area of 10 m², cruising at 50 m/s (100 knots TAS) at its MTOW of 540 kg and at an altitude where the air density is 1 kg/m³ — about 6000 feet. The lift force being produced must equal the gross aircraft weight (mass multiplied by the acceleration of gravity, which is near enough to 10 m/s²), thus the weight is 540 × 10 = 5400 newtons [N] and the lift from the wing must be the same — ignoring the tailplane/canard balance needs. The lift equation in level flight is: lift = CL × ½rV² × S = weight where CL is the non-dimensional lift coefficient, r is the air density in kg/m³, V is the true airspeed in m/s and S is the wing area in m². Substituting the Model A values in the equation, then CL × ½ × 1 × 50 × 50 × 10 = 5400 so the value of CL in the cruise with zero flap must be 0.43 and aoa would be around 4°. The 'lift coefficient — aoa curve' diagram is a generalisation of the relationship between CL and aoa for a normally cambered wing, which reaches the zero lift aoa at around 2° negative, and the critical aoa at 16° where CLmax is 1.3. The slope of the 'lift curve' is such that each 1° aoa change, within the 2° to 12° range, increases/decreases CL by around 0.1. Now suppose our Model A aeroplane cruising at 50 m/s encounters a sharp-edged thermal that has a velocity of 7.5 m/s (1500 fpm or 25 fps), then the aircraft aoa will increase by 9° to about 13°. (Using the 1-in-60 rule: 7.5/50 × 60 = 9.) In addition, the speed of the airflow relative to the wing will increase very slightly to 50.5 m/s as shown in the diagram 'Effect of updraft encounter on aoa' below. (The diagram is much the same as the wind triangle plot you might use in navigation — the 'effective change in aoa' is comparable to the drift angle, and the 'effective airspeed' is comparable to the ground speed.) The lift coefficient increases by around 0.1 per 1° aoa change so the value of CL will now be around 1.3, the 'CL — aoa curve' indicates 1.2. Ignoring the very slight airspeed change we can calculate the lift force produced under the changed conditions: i.e. lift force = 1.2 × ½ × 1 × 50 × 50 × 10 = 15 000 N. Thus entry to the gust has increased CL from 0.43 to 1.2 (i.e. 2.8 times) and induced a momentary increase in total wing loading from 5400 to 15 000 N. This applies a rapid bending moment to the wings, flexing them up but well within the design limit load for normal category aircraft of +3.8g, or 20 520 N (5400 × 3.8) total wing loading for our aircraft. (Design limit loads were discussed in the module 'Don't fly real fast', but be aware that the extension of flaps reduces the limit load factors by as much as 50%.) A very short time after that initial entry into the gust, the inertial effects are overcome, the +2.8g load (15 000/5400) accelerates the aircraft upwards — felt by the occupants as a very severe jolt pushing the seat up under them but also 'felt' as a sudden 2.8g load by all other parts of the aircraft's structure — and the wings' elastic reaction also adds some impetus to the fuselage. The acceleration alleviates the gust loads on the wing while the aircraft restores itself to its trimmed angle of attack and flight continues normally; except that the new flight path will incorporate a rate of ascent relative to the Earth, equivalent to the updraft speed. When the aircraft flies out of the updraft it will again momentarily maintain its flight path relative to the Earth. During that time the effective airflow around the wings will no longer be directly aligned with the flight path but will have acquired a vertical component opposite to that at entry. The aoa and consequently CL will decrease, producing a momentary decrease in wing loading. The airframe will experience a negative g load, and perhaps the occupants will feel the shoulder harness stopping them being thrown out of the seat, before the aircraft is finally restored to level, unaccelerated flight. Encounter with a strong updraft Now let's consider the Model A aircraft cruising at 120 knots (60 m/s) with CL of 0.3 encountering a 2000 fpm (10 m/s or 33 fps) gust. The encounter would increase aoa by 10° and CL to about 1.15, so: lift produced = 1.15 × ½ × 1 × 60 × 60 × 10 = 20 700 N. Thus entry to the gust has produced a momentary increase in total wing loading from 5400 to 20 700 N imparting a +3.8g load (20 700/5400), which is around the 20 520 N wing load limit as well as the 3.8g airframe load limit. The change in load is from +1g to +3.8g, which will impart a 2.8g acceleration. Note that if our aircraft had been cruising at less than 50 m/s, when the 10 m/s gust was encountered the aoa change would exceed 12° and consequently the critical aoa. The airflow over the wing would separate instantly and alleviate the gust load; this is relevant to Va, the design manoeuvre speed. It is also assumed above that the aircraft is in unaccelerated flight when the gust is encountered. If the aircraft were in a 40° banked turn then the manoeuvring load factor would be 1.3g rather than 1g, and the gust-induced load would be added to the basic manoeuvring load. If it were in a 60° banked turn then the basic load would be 2g, and the manoeuvre plus gust acceleration would be 4.8g; this is getting very close to the ultimate load factor and in the zone where component fatigue could cause premature structural failure. Effect of lower aircraft weight If an aircraft is well below MTOW there is a significant effect on structural loads developed in a vertical gust. Let's take our Model A with only one person on board and less fuel so that weight is reduced to 450 kg or 4500 N, again cruising at 60 m/s and still at an altitude where the air density is 1 kg/m³. So substituting those values in the equation then CL × ½ × 1 × 60 × 60 × 10 = 4500 and the value of CL in the cruise must now be reduced to 0.25 and the aoa reduced to about 1°. Now suppose that aircraft encounters the same 2000 fpm (10 m/s) updraft. Then the aircraft aoa will again increase by 10° but to about 11° and CL of 1.05. We can calculate the lift force produced under the changed conditions: lift produced = 1.05 × ½ × 1 × 60 × 60 × 10 = 18 900 N. Thus entry to the gust at the lower weight has increased CL from 0.25 to 1.05 (i.e. 4.2 times) and induced a momentary increase in total wing loading from 4500 to 18 900 N (4.2g). This is well within the 20 520 N (5400 × 3.8) total wing loading limit for this aircraft but outside the 3.8g design load limit for the structural parts — the mounting structures for the engine, battery and occupant seats, for example. So when operating at significantly lower weight (and thus lower wing loading) an encounter with a vertical gust at a particular flight speed will induce greater accelerations than when operating near MTOW, which obviously affects choice of speed in turbulent conditions. Effect of speed From the foregoing we could deduce that the faster a particular aircraft's speed is when encountering vertical gust shear, the lesser the structural loads developed. This is because the change in effective angle of attack will lessen as forward speed increases. However, angles of attack at higher speeds are much lower, so the effective CL change from a gust encounter is then proportionately greater. (But it depends to some extent on the slope of the lift curve and the wing loading.) For example, take our fully laden Model A flying at both 80 knots and 120 knots at 6000 feet; CL at the slower speed would be 0.7 and 0.3 at the faster speed. If, in both cases, the aircraft encountered a 500 fpm thermal the aoa changes would be about 4° and 2.5°, increasing CL to 1.0 and 0.5 respectively. The acceleration would be about 1.4g (1.0/0.7) at the slower speed but 1.7g (0.5/0.3) at the faster, so acceleration loads increase as airspeed increases and that increase is amplified by increasing gust velocity. This doesn't alter the fact that a high wing-loading aircraft will provide a better ride in turbulence than a low wing-loading [W/S] aircraft, at the same high speed. Imagine two different aircraft types having the same weight but different wing area; if they are flying at the same speed and encounter the same vertical gust, the change in aoa and thus CL will be roughly the same for both. However, the low W/S aircraft will experience a higher acceleration because its wing area is greater and thus the total induced load is greater. We will discuss speed to fly in turbulence later in this module. Encounter with a downdraft Now suppose the Model A aircraft cruising at 50 m/s (4° aoa) encounters a sharp-edged downdraft that has a velocity of 7.5 metres/second (1500 fpm). Then the aircraft aoa will decrease by 9° to about 5° negative where, from the CL – aoa curve, CL will perhaps be around 0.2 negative. The airspeed relative to the wing will change slightly but can be ignored. We can calculate the lift force produced under the changed conditions: lift force produced = –0.2 × ½ × 1 × 50 × 50 × 10 = −2500 N A negative value means the lift force is acting opposite to the norm. Thus the entry to the downdraft has produced a momentary change in total wing loading from 5400 N positive to 2500 N negative, producing a 0.5 negative g load (–2500/5400) and resulting in a 1.5g negative acceleration from +1g to –0.5g. The occupants will be restrained by their harnesses while the seat drops away from them. Following initial entry into the downdraft the inertial effects are overcome and the aircraft will restore itself to its trimmed angle of attack and flight will continue normally — except that the new flight path will incorporate a rate of sink relative to the Earth and equivalent to the atmospheric downflow. Note the difference in the acceleration between the 1500 fpm updraft and 1500 downdraft encounter at the same cruise speed — the updraft produced a 2.8g acceleration, the downdraft only a 1.5g acceleration. When the aircraft flies out of the downflow it will again momentarily maintain its flight path relative to the Earth. During that time the effective airflow around the wings will no longer be directly aligned with the flight path but will have acquired a vertical component opposite to that at entry. The aoa and consequently CL will increase producing a momentary increase in wing loading, and the airframe will experience a positive g load before the aircraft is finally re-established in level flight. Thus encountering changes in vertical flow induces momentary changes in aoa and wing loading. The gust accelerations and the variation in the vertical profile of the flight path will be considerable if extensive and higher-speed vertical gusts are encountered. But it's a bit more complex! The foregoing assessments of aircraft reaction to updraft/downdraft shear is simplified, but aircraft reactions are much more complex. For example: the calculations have been done assuming a 'sharp-edged gust' which probably doesn't exist; aircraft designers include a 'gust alleviation factor' in their calculations; the gust-induced aoa change also changes the wing pitching moments; the tailplane is flying perhaps 50 milliseconds behind the wing and will also be affected by the gust loads, so the stabiliser pitching moment will be out of sync with the wing pitching moment and the aircraft will pitch up or down accordingly; air velocity within the gust will not be smooth and constant, yawing and rolling forces will be applied, and buffeting may occur; changes in aoa must result in momentary changes in induced drag but the aircraft's inertia will probably maintain its motion; and a canard aircraft will be affected differently from a tailplane aircraft. The accelerations calculated in the foregoing are those measured at the aircraft's cg. Accelerations at the aircraft's extremities may be much greater due to added yawing, rolling and/or pitching motions and they will also affect the control surfaces. 6.7.3 Surface gusts or low-level wind shear Gust ratios In normal flying weather the velocity of any near-surface wind is changing constantly. Due to the eddies that usually exist within the flow, fluctuations in direction of 20° or so and in speed perhaps 25% either side of the mean, occur every minute. In other than very light wind conditions these variations are evident in the form of wind gusts. In stronger wind conditions, gust ratios (maximum gust to mean wind speed) are typically 1.6:1 over open country and 2:1 or greater over rough terrain, adding more turbulence to the flow. In an unstable atmospheric boundary layer the rising air in thermals is complemented by colder air sinking from the top of the layer, where the wind velocity approximates the gradient flow; i.e. the direction may be backed by 20–30° from the wind at the surface, and the speed is greater. The descending air retains most of these characteristics when it arrives at the surface as a strong gust, thus backing (i.e. shifting anticlockwise around the compass) and increasing in speed. Very light aircraft are of course more susceptible than others to low-level gusts. Such gusts figure in light aircraft accidents perhaps ten times more often than all other forms of windshear or turbulence combined. However, such upsets don't often result in serious injury to the occupants, and coping with such conditions in take-off and landing is an everyday part of pilot development. This module is concerned with more unusual events. Horizontal shear effects Horizontal shear is the change in horizontal wind velocity (speed and/or direction — gusts and lulls) with horizontal distance flown; i.e. a substantial change in the ambient energy state of the air mass in which the aircraft is borne. Horizontal shear is particularly dangerous when landing, taking off or going around as headwinds can suddenly disappear or change to strong crosswind gusts. These can last anywhere from a few seconds to several minutes. Crosswinds can change to tailwinds, resulting in loss of control and ground collision. There are two general classifications for horizontal shear. Increasing-performance shear. If a low-flying aircraft suddenly encounters an increase in the headwind component of wind speed (or a decrease in a tailwind) then due to its inertia the aircraft will momentarily maintain its speed (and flight path) relative to the Earth. Thus there will be a brief increase in speed of flow over the wings with consequent increase in lift. The aircraft will rise, gaining potential energy, until the inertial effects are overcome and the aircraft restores itself to the previous flight state at a higher altitude than previously; but at a changed ground speed and track — if the changed wind velocity is maintained. Decreasing-performance shear. Similarly should the aircraft encounter a decrease in the headwind component (a lull, or a gust from the rear) then airspeed and lift will decrease, and the aircraft will sink until the inertial effects are overcome. In recreational light aircraft flight conditions (and in accordance with the lift equation) the percentage increase or decrease in lift will be about double the percentage increase or decrease in airspeed; i.e. if airspeed dropped by 10% then lift will drop by 20% and the aircraft will sink very quickly. The worst situations to encounter such shear are where loss of airspeed and/or a sudden loss of height, take-off or climb performance could be critical — on the final approach to landing, on take-off or during a go-around . The time taken for the aircraft to restore itself to the original airspeed will be much the same as that taken to gain — in normal conditions — the same increase in airspeed by increasing power. Usually increasing-performance shear should not present any problem to an aircraft on approach or take-off, as long as the pilot continues to maintain the appropriate attitude in pitch, ignoring the speed increase(s), and is prepared for a possible decreasing-performance shear encounter to follow. On the other hand decreasing-performance shear will be very dangerous if the aircraft has insufficient height to clear obstacles while the pilot takes action to accelerate the aircraft through the shear and minimise height loss. If the aircraft's initial airspeed was less than the safe speed near the ground, including the normal 50% gust estimate allowance, then the shear effect is exacerbated and the rate of sink could be extremely high. Wind shear occurring just after wheels-off can cause the aircraft to stop accelerating. Wind shear events are usually a combination of wind speed variations and variations in three-dimensional direction, which will affect aircraft speed, angle of attack and attitude in the three axes. Thus encountering changes in horizontal flow within the airmass causes momentary changes in lift. There are consequent variations in the vertical profile of the flight path plus — with significant wind direction changes — diversions from the planned ground path and uncommanded motions in roll, yaw and pitch. Increasing-performance shear could even stall the aircraft: imagine an aircraft in slower level flight encountering a 20-knot gust vector at 45° to the horizontal. The effect would be like encountering a 14-knot head-on gust combined with a 25 fps updraft — the airspeed would be increased but the vertical gust component could take aoa past critical, so we have an accelerated stall. Something you can be sure of is that no matter what scientists and aviators may do to place wind shear and turbulence events into tidy boxes, the atmosphere has never been a party to such classification and will, on occasion and literally out of the blue, produce a demonstration of staggering power that just confounds our experience and expectations. Various scenarios were outlined in the 'Don't stall and spin in from a turn' module where the aircraft could be flying with little margin between effective and critical aoa; it is on occasions like these that Murphy's Law springs into action. What can and will go wrong at those worse possible times is an encounter with wind shear or turbulence that suddenly increases the effective aoa of the wing and instantly switches on a stall/spin event or a high sink rate at the worst possible time. Vertical shear (unrelated to vertical gust shear) is the term used for the change in the roughly horizontal wind velocity with change in height; i.e. as the aircraft is climbing or descending. As the vertical component of a light aircraft's velocity during climb or descent is probably no more than 12% of its horizontal velocity, the outcome of vertical shear is much the same as that for horizontal shear so we'll ignore the term and talk about the wind gradient. The wind gradient The Earth's surface has a frictional interaction with the atmosphere. Its effect decreases with height, until between 1500 and 3000 feet agl the gradient wind (i.e. the wind more or less is aligned with the isobars on the meteorological surface chart) dominates. The stability of that 'friction' or 'boundary' layer between the surface and the gradient wind level affects the strength of the friction force. A very stable layer suppresses turbulence and friction is weak except near the surface. In a superadiabatic layer convective turbulence is very strong and the friction force will be strong. In a typically neutral layer, with a moderately strong gradient wind of about 30 knots at 2500 feet, the wind speed might be 20 knots at 750 feet but only 10 knots at the surface. There is also a change in wind direction within the layer, perhaps as much as 40°. The rate of change in the gradient wind speed is generally more pronounced within the lower 300 feet, while the change in direction in that first 300 feet is negligible in strong winds but greatest in light winds, perhaps as much as 15–20° if the surface wind is less than 5 knots. The profile of the wind velocity change between the gradient wind and the surface wind is called the wind gradient. The greatest change in wind gradient velocities occurs at night and early morning. If the gradient wind speed is 30 knots at 2500 feet agl and reduces uniformly to 10 knots at the surface then, although the 20-knot change is relatively high, the time taken for a light aircraft to descend for landing through that wind profile is measured in minutes; thus there is no shear because the rate of change is slow. Remember in aviation terms wind shear is a sudden but sustained 'variation in wind along the flight path of a pattern, intensity and duration, that displaces the aircraft abruptly from its intended path and sufficiently that substantial and timely control action is needed.' So the average recreational light aircraft is not adversely affected by the normal (see Note 3) wind gradient provided that the minimum safe speed is maintained during take-off and landing, and the pilot remains aware of the gradient effects on the flight path/speed profile, adjusting the usual piloting techniques accordingly. (Note: 'normal' for the average recreational light aircraft implies a surface wind no more than 'moderate'; i.e. less than 16 knots or the point at which a dry '15 knot' windsock becomes horizontal. Greater surface wind speed could indicate a more pronounced gradient and thus possible shear conditions within the gradient.) 6.7.4 The speed to fly in turbulence Vno — maximum structural cruise speed In light aircraft the green arc on the airspeed indicator should indicate the 'normal operating' range between Vs1 at the lower limit, and Vno, or perhaps Vc, at the upper limit. Vno is the maximum structural cruise speed and, when cruising at and below Vno, the airframe would not be put at risk of overstressing in an encounter with turbulence in the upper end of the moderate range. Flight in the yellow arc speed range between Vno/Vc and Vne should only be conducted using controls cautiously and in reasonably smooth atmospheric conditions. Vc — design cruising speed Vc is normally not a limiting speed — it is a value chosen by the designer as a basis for stress calculations. In the FAR Part 23 regulation normal category, Vc in knots may not be less than 33 times the square root of the aircraft wing loading in pounds/square feet. For example 'minimum' Vc for an aircraft with 9 lb/ft² weight/wing area ratio (about 45 kg/m²) would be 33 × 3 = 99 knots. Alternatively the designer is allowed to obtain a lower speed value by setting Vc at 90% of Vh — the maximum level flight speed attainable at sea level whilst utilising maximum continuous engine power. Vno must not be less than the minimum Vc and for light aircraft Vc and Vno can be considered synonymous. The representative gust envelope, below, for a normal category aircraft superimposes positive and negative vertical gust load lines over a manoeuvring V-n diagram similar to that shown in the 'Airspeed and properties of air' tutorial. The horizontal light blue line indicates airspeed increasing from zero. The calculated gust load lines originate at the normal flight load condition of +1g, the strong 50 fps (30 knot) gust line extending to Vc and the moderate 25 fps (15 knot) line extending to Vd (the design diving speed). You can see that the moderate line intersects with Va at about 2g (i.e. a 1g acceleration) and with Vc at about 2.8g (a 1.8g acceleration). The strong gust line intersects with Va at about 3g and with Vc at something in excess of the 3.8g limit load. The brown arrow shows the 2.5g load — added to the normal 1g load — when the aircraft, flying at a speed about 30% higher than Va, encounters a 50 fps updraught. The total load factor is then about 3.5g; within the limit load factor, even though the gust is at the low end of the strong gust category. The pink arrow shows the resultant 2g load when the aircraft, flying at a speed about 30% higher than Vc, encounters a 25 fps updraught. Adding the normal 1g load the total load factor is then 3g. So even when flying at a speed somewhat greater than Vc/Vno in a certified light aircraft, an encounter with a vertical gust at the low end of the moderate gust range would be no problem. The calculations designers use to establish the gust load lines is similar to those used in the preceding section 'Vertical gust effects' but more refined; e.g. using a 'gust alleviation factor' rather simplifying the calculation with the concept of a 'sharp-edged gust'. FAR 23 Appendix A provides simplified design load criteria and allows designers of many conventional single-engine monoplanes weighing less than 2700 kg to take advantage of the simplification. That same appendix is generally duplicated in the design regulations of most other countries. One advantage of interest to us is that it is not necessary to specify Vno; instead, Vc is designated in the flight manual as the maximum structural cruise speed (i.e. Vno = Vc) and that Vc is probably set at 90% of Vh, as mentioned above. Va — design manoeuvring speed Almost all recreational light aircraft are built to simplified design standards that may not include rational consideration of gust loads — and there is no requirement for designers to publish a 'turbulence penetration' speed. For such aircraft, the maximum speed in anything approaching rough air is the design manoeuvring speed, so aircraft flight manuals or Pilot's Operating Handbooks nominate Va, which is usually considerably lower than Vc, as the speed to fly in 'turbulence'. There are other advantages in nominating the lower speed; e.g. most pilots have difficulties in classifying the turbulence being experienced (one pilot's 'moderate' may be another's 'extreme') and in controlling an aircraft in even moderate turbulence without experiencing considerable variation in speed. So rather than nominating a 'rough air' speed or a 'turbulence penetration' speed, manufacturers specify Va as the 'speed to fly' in turbulence. Before going further, we should examine how Va is derived. At higher speeds the wing lift coefficient (i.e. the aoa plus flap/slat/spoiler configuration) is relatively low, with much of the lift being provided by the dynamic pressure due to the airspeed — so the lifting force potential of the wing is very high. In these circumstances the wing loading might be readily tripled or quadrupled through abrupt and excessive elevator movement. For example if the aircraft was flying with CL = 0.25 and the pilot suddenly pulled back hard on the stick then CL might increase to 0.75 applying a momentary 3g load made up of the pre-existing 1g normal load plus the 2g acceleration. So it is unwise to make full or abrupt applications of any one primary flight control if flying at a speed greater than Va. This is because at the higher speeds it is easy to apply forces that could exceed the airframe structural limitations, and particularly so if you apply non-symmetrical loads; e.g. apply lots of elevator and rudder together. Misuse of controls in light aircraft at high speed can generate greater structural loads than those likely to be encountered in turbulence, so Va is also useful as a 'turbulent air operating speed'. At this compromise speed the aircraft will produce an accelerated stall, and thus alleviate the aerodynamic load on the wings, if it encounters a vertical gust imparting an acceleration sufficient to exceed the load limit factor. Aircraft design rules generally state that the minimum acceptable manoeuvring speed is a fixed calculation relative to Vs1 for all aircraft within the same category; for a normal category light aircraft (whose certificated vertical load limit factor is +3.8g) minimum Va = Ö3.8 Vs1 or 1.95 × Vs1. Of course the aircraft designer may specify a Va speed that is greater than the minimum requirement. The sample gust envelope diagram indicates that particular aircraft at Va could handle a vertical gust speed greater than 50 fps without reaching the load limit. All the preceding assumes the airspeed indicator has been properly calibrated and Va is stated as a calibrated airspeed. If it has not been accurately calibrated each one knot error in IAS around Va speeds will make a 0.1g difference in wing loading; i.e. if the ASI is understating airspeed by 10 knots then the load is 1g greater than thought. For more Va information see 'Critical limiting speeds'. What speed then? Follow the recommendations in the manufacturer's approved documentation. However, if that lacks substance then the following is relevant. If in cruising flight at speeds at or below Vno/Vc and 'very low' to 'low' turbulence is encountered, speed could be maintained without detriment, but be prepared to slow down if you suspect it may become rougher or if conditions suit the development of fast-rising thermals. If turbulence is in the moderate to severe category, reduce speed to the weight-adjusted Va. If flight at this speed is still worrying then speed could be reduced further. But when flying in moderate to severe turbulence at speeds below the weight-adjusted Va, then although the potential for exceeding load limits is no longer a problem, the potential for loss of control is much increased. As speed is reduced below Va updraft encounters produce increasing changes in aoa. This increases the potential for stall and in rough conditions even transient stalls may lead to longer-term loss of control with possible spin entry — and spins in severe turbulence may not be quickly recoverable. Loss of control may also lead to airspeed exceeding Va and thus restoring the potential to exceed load limits. Normal minimum safe speed in fairly smooth air is 1.5 × Vs1, but in very rough conditions the lower limit should be perhaps 1.7 × Vs1. You can see from the V-n diagram that the intersection of the 50 fps gust line and the Cna curve corresponds with a load factor of about 2.8g. The stall speed is escalated by the square root of the load factor and the square root of 2.8 = 1.7. If there is no manufacturer's documentation or instrument panel placard indicating manoeuvring speed, or a speed to fly in turbulence, then assume maximum weight Va is twice Vs1 CAS. If weight is below MTOW reduce Va by one half of the percentage weight reduction; e.g. if weight is 16% below MTOW, reduce Va by 8%. In addition it should be recognised that some sport and recreational light aircraft are ageing, the strength of their airframe components is not 'as new' and the designed ultimate load limit factor is no longer achievable. 6.7.5 Coping with shear and turbulence Prudent actions The action to take in encounters with turbulence or shear very much depends on your interpretation of events. For example if, in cruising flight, you believe you have entered just a limited layer of turbulence then you would initiate a shallow descent or climb to find smoother air. At the other extreme is a cruising flight encounter with a severe vertical gust or other severe turbulence, where your actions might be: set and tighten the engine control(s) to provide power appropriate to the Va target and then try to hold a straight and level attitude — if it's really rough you might need both hands on the control column tighten harnesses; you should not have any loose objects in the aircraft. don't chase the airspeed indicator (which may well be giving transient erroneous indications anyway), just hold the attitude as much as possible. (If turbulence is really rough it may be impossible to read the instruments, not least perhaps because your eyes are not able to refocus quickly enough.) don't over-react to changes in altitude avoid adding any manoeuvring loads such as those that are applied if you attempt a 180° turn; and certainly don't make abrupt asymmetric manoeuvres. Do not extend flaps, as in most light aircraft the effect is to reduce the structural limit load factor, full flap usually by about 50% to around 2g. If controllability is becoming difficult and the aircraft has retractable undercarriage then lower it — the drag reduces higher speed excursions and the lower drag line seems to reduce yaw. After escaping turbulence do not retract the undercarriage; inspect the area for damage immediately after landing. In excessive uplift, rather than going with the flow it may be prudent to reduce power and lower the nose somewhat to maintain target speed. It depends on what is above you — a towering cumulus or Class C airspace for example. If you are likely to violate controlled airspace notify Flight Service on the area frequency and ensure the transponder, if available, is operating. If you have the ability, then inform Flight Service of the turbulence encounter and location — the pilot report may help others to avoid it. Generally an aircraft will not run into a severe downdraft at low levels, more likely it will meet the turbulent low-level horizontal outflow from the downdraft. However, if you encounter a severe downdraft at lower levels, the only option is to immediately apply full power and either adopt the attitude for best rate of climb or allow airspeed to increase even beyond Va and trust you will fly out of the downdraft quickly. Whichever way the pilot is in a hazardous situation, and the aim should be to recognise and avoid extreme shear conditions. Upset recovery Many windshear or turbulence encounters will result in an uncommanded roll perhaps combined with strong yaw, pitch-up or pitch-down. The result may well be an aircraft in a most abnormal attitude and losing height fast. Such events are very dangerous at low level. Most light aircraft don't have much roll capability, perhaps 15–30° per second is the norm. If a condition such as a curl-over, a lee wave rotor or the wing tip vortices from a preceding larger aircraft (for example when turning base to final following a larger aircraft landing from a straight-in approach), is encountered, the resulting induced roll may well exceed the countering capability of the ailerons. As mentioned in the 'Engine failure after take-off' module under the sub-heading 'Unloading the wings is a good practice to practise' a light aircraft (but not a trike) can be better controlled for at least a few seconds, even at sub-Vs speeds, by pushing forward to unload the wings so that the aircraft is operating in the reduced-g zone (between perhaps +0.25g and +0.75g) but not in the negative-g zone'. In the 'Don't stall and spin in from a turn' module under the sub-heading 'When I recognise a stall with wing drop what's the best way to recover?' a stall recovery technique was presented. That same technique is applicable to recovery from an abnormal attitude (where the primary aim is to get all lift force directed away from the ground), except that the initial forward stick movement should unload the wings rather than just reducing aoa below critical. Centralise the ailerons and unload the wings to a reduced-g level, even if steeply banked or inverted. This may be a difficult decision if the nose is already pitched down and not much height is available, but certainly keep the stick forward of neutral. Increase power smoothly, up to maximum if low and slow, but if the nose is pitched down and speed is above or accelerating towards Va then reduce power. Don't wait for the engine to fully respond before moving to the next actions. If the aircraft is inverted, then close the throttle to improve subsequent responsiveness. Cancel any yaw with rudder, and centre the slip ball. This and the two preceding items should be near-simultaneous actions. While maintaining the low wing loading, roll the wings level with aileron so that all the lift force will be directed away from the ground, and use coordinated rudder to assist the ailerons. If near inverted, choose the roll direction that provides quicker return to a wings-level attitude but if the ailerons can't counter the induced roll then you might take advantage of the roll momentum and continue to roll through. As the wings are nearing level, ease the stick back to the neutral position, or just aft of it, to correct the attitude in pitch. When safe, adjust attitude and power as necessary for the climb-out. If on an approach to landing, then go around — and take your time starting the next approach. STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

6.6.1 Why the high fatality rate? Loss of control The primary causal factor for the generally high fatality/severe injury rate is loss of control in a mistimed/poorly executed initial turn, perhaps being intimidated by terrain/obstructions; or, following a successful 180° turn, realising too late the airfield can't be reached resulting in an unplanned, perhaps desperate, reaction. The factors involved in loss of control events were discussed in the article 'Don't stall and spin in from a turn'. Here's an extract from an RA-Aus accident report compiled by a qualified witness on behalf of the severely injured pilot. At the time, the pilot had a CPL and RA-Aus Pilot Certificate but only 2 hours experience in his Supercat CAO 95.10 aircraft. The crash occurred from a 900-metre runway at an airfield in mountainous terrain, at an elevation of 3300 feet. At the time, wind was light and variable with no turbulence, and temperature corresponded to the ISA norm. Apparently partial loss of thrust was experienced on take-off. " The aircraft took off normally ... climbed to 150–200 feet near the end of the runway ... then appeared to sink and turn left ...(there is a power line 300 m past the runway end, below runway level in a ravine)... the angle of bank increased rapidly until it appeared to be almost 90°. The aircraft descended rapidly and disappeared behind some trees followed by a surprisingly soft 'crump'." The aircraft hit the ground almost vertically. 6.6.2 Opting for the turn-back The need for a properly derived decision The conventional and generally long-accepted wisdom in the event of a low-level off-field failure is for a properly controlled landing — hopefully into wind, more or less straight ahead, but certainly somewhere within 60° either side of the initial path. Factors involved were examined in the three preceding modules of this series. If the engine fails well into the climb-out one of the possible options is to turn back and land on the departure field. If the take-off and climb was into wind and a height of perhaps 1500 feet agl had been attained (and the rate of sink is less than the rate of climb) then there would be every reason to turn back and land on that perfectly good airfield. There may be sufficient height in hand to manoeuvre for a normal, but close, circuit; or otherwise a crosswind, rather than a difficult downwind, contra-traffic landing. On the other hand there will be a minimum 'decision height' below which a turn-back for a landing in any direction could clearly not be accomplished; and of course there will be an associated maximum distance. The only logical basis for opting for a turn-back, rather than landing somewhere within that 120° arc ahead of you, is a properly derived decision that it is by far the safest choice. This requires knowledge of the dynamics involved in the turn-back and of the relevant characteristics of the aircraft being flown. Knowledge of the latter can only be gained by practising accurate, low-speed, fully banked gliding turns at a safe height and measuring the height lost in the turn plus the distance:height ratio at Vbg. 6.6.3 Turning back — procedure and dynamics The repositioning manoeuvre Turning back to land on, or parallel to, the departure runway is a two-stage procedure. This comprises a repositioning manoeuvre, turning through maybe 210°, so that the aircraft is positioned as close as possible to the extended runway line at sufficient height to then glide directly back to the planned touchdown point at Vbg — the speed that provides the best L/D ratio and thus optimum distance in a straight glide. A small turn will be needed to finally align with the selected landing path. If the take-off has a crosswind component, the initial turn should be conducted into the crosswind so that the aircraft will drift towards the extended runway line and also reduce the ground diameter of the turn a little. If the take-off has been downwind because of runway slope then the minimum height for a turn-back would be greatly increased; if there are any doubts don't turn back — except as needed for an into-wind off-field landing. Of course there is no need to opt just for a runway if you have departed from a larger airfield with ample cleared area available for an emergency landing. While repositioning, it is important to minimise the time spent in the turn and thus the height loss, so gliding at Vbg or even Vmp is not a requirement; but choice of an optimum turn speed is vital. Turn speed, diameter and rate of turn The air radius of a turn is directly proportional to the true airspeed squared and indirectly proportional to the angle of bank. The rate of turn is directly proportional to the angle of bank and indirectly proportional to the speed. Table 5.1 shows some calculations for various bank angles at speeds of 40, 50, 60 and 70 knots. The calculations are based on two slightly simplified but accurate equations applicable to all light aircraft: The turn diameter (metres) = the airspeed (metres per second) squared divided by 5 × the tangent of the bank angle. Example: airspeed 60 knots (30 m/sec), bank angle 30° and tangent 30° is close to 0.6. Turn diameter = 30 × 30/5 × 0.6 = 900/3 = 300 metres. The rate of turn (degrees per second) = the tangent of the bank angle × 1100 divided by the airspeed in knots. Example: bank angle 45°, tangent 45° is 1.0 and airspeed 40 knots. Rate of turn = 1.0 × 1100/40 = 1100/40 =28°/sec. So time to turn through 210° = 8 seconds. Note 1: a rate 1 turn is 3°/sec, a rate 2 turn is 6°/sec, a rate 3 turn is 9°/sec, and a rate 4 turn is 12°/sec. Very heavy transport aircraft normally turn at 1.5°/sec. Table 5.1 Turn diameters and turn times Airspeed (knots CAS) Bank angle Tangent Turn diameter (metres) Turn rate (°/sec) Time to turn through 210° (seconds) 40 10° 0.2 400 m 5 42 s (20 m/s) 20° 0.4 200 m 11 19 s 30° 0.6 135 m 16 13 s 45° 1.0 80 m 28 8 s 60° 1.7 45 m 48 4 s 50 10° 0.2 625 m 4 53 s (25 m/s) 20° 0.4 310 m 9 23 s 30° 0.6 210 m 13 16 s 45° 1.0 125 m 22 10 s 60° 1.7 73 m 38 6 s 60 10° 0.2 900 m 3.7 57 s (30 m/s) 20° 0.4 450 m 7.4 28 s 30° 0.6 300 m 11 19 s 45° 1.0 180 m 18 12 s 60° 1.7 105 m 32 7 s 70 10° 0.2 1225 m 3.1 67 s (35 m/s) 20° 0.4 610 m 6.3 33 s 30° 0.6 410 m 9 23 s 45° 1.0 245 m 16 13 s 60° 1.7 140 m 27 8 s It can be seen that both a greatly reduced turn diameter and a very fast turn rate are achieved at the lowest speed coupled with the highest bank angle, with the bank angle being more significant than the airspeed. So the stall speed of the aircraft has some importance; the ultralight with a very low Vs1 can produce a very fast small diameter turn. Note from the table that at all speeds the time to turn through 210° and the air diameter of the turn are around four times better with 60° bank than with 20°. However, the third factor to be considered when selecting the bank angle and airspeed is the rate of sink relative to the bank angle. Bank angle, stall speed in the turn and rate of sink The 'turn forces' diagram shows the relationships between total lift force, bank angle, weight and the centripetal force required to make the turn. In the turn, the vertical component [Lvc] of the total lift force just about balances aircraft weight, and the horizontal component of lift [Lhc] provides the centripetal force to minimise the turn radius. At 30° bank angle Lhc = 0.6 Lvc while at 60° Lhc = 1.7 Lvc. So to provide the centripetal force for a sustained turn, the wing loading must be increased by pulling g as angle of bank increases; rather slowly up to a bank angle of 30° — where it is 15% greater than normal level flight loading — after which it escalates. The diagram is for a powered level turn, but the principles are much the same for a gliding turn. Except that in the level turn, the airspeed is generally held constant and the increase in total lift force is gained by increasing angle of attack; the consequent increase in induced drag is countered by increasing thrust. In a gliding turn the increase in total lift force is obtained by both increasing the angle of attack (pulling g) as bank increases and increasing the airspeed by lowering the nose; the rate of sink accelerates as airspeed and aoa (thus induced drag) increase. Table 5.2 is a sample profile of the increase in sink rate in a sustained gliding turn at particular bank angles. The base sink rate is the minimum sink achievable in a straight glide at Vmp. The fourth column shows the increase in turn stall speed and the last column is a representative estimate of the increase in rate of sink in the turn if the airspeed chosen was about 10% higher than the turn stall speed [i.e. for 45° bank airspeed = 1.3 Vs1]. Note: L/D or glide ratio [actually Lvc/D] deteriorates markedly as bank angle increases because of the escalating induced drag as more g is pulled. Table 5.2: stall speed/sink rate in a sustained gliding turn Bank angle Cosine Load factor (=1/cos angle) Vs1 multiplier (increase) Sink rate multiplier (See note 1 below) 10° 0.98 1.02g 1.01 (+1%) 1.05 (+5%) 20° 0.94 1.06g 1.03 (+3%) 1.15 (+15%) 30° 0.87 1.15g 1.07 (+7%) 1.3 (+30%) 45° 0.71 1.41g 1.19 (+19%) 1.9 (+90%) 60° 0.50 2.00g 1.41 (+41%) 3.5 (+250%) Note 2: the comparative sink rates shown in the right-hand column will vary substantially with each aircraft type/model. The late Tony Hayes of the Thruster Operations Support Group kindly produced some Thruster T300 trial data, which showed that in a 45° bank gliding turn at 55 knots (1.3 Vs1) the sink rate was 900 fpm, or 3 times the Vmp sink rate of 300 fpm. If the turn was conducted at 59 knots (1.4 Vs1) the sink rate increased to 1050 fpm or 3.5 times minimum sink in a straight glide. The sink rate in a straight glide at Vbg (48 knots) was 400 fpm. The trials were conducted soon after sunrise in a calm, stable atmosphere thereby providing best results. Sink rates would be worse in normal everyday conditions. Choosing the bank angle Obviously the height lost in the turn is a function of the rate of sink and the time spent in the turn. Table 5.3 is a calculation for a hypothetical ultralight that has a Vs1 of 40 knots and a minimum rate of sink in a straight glide of 420 fpm or 7 feet per second. The airspeed selected for the turn is just 10% greater than the stall speed (Vs[turn]) at those bank angles. Table 5.3 Height lost in a 210° turn. (Vs1=40 knots, minimum sink =420 fpm or 7 fps) Bank angle Vs (turn) +10% (knots) Turn diameter (metres) Turn time (seconds) Sink rate (fps) Height lost in turn (feet) 10° 44 540 m 46 7+ 330 ft 20° 45 280 m 24 8 190 ft 30° 47 190 m 15 9 135 ft 45° 52 135 m 10 13 130 ft 60° 62 110 m 7 24 170 ft It can be seen that a 45° bank angle, where Lhc = Lvc — i.e. the wing loading is equally distributed between countering gravity and providing the centripetal force — allows the least height loss. The height loss at a 30° bank angle is much the same but the lesser bank gives a larger turn diameter. Bank angles less than 30° or greater than 45° are not as efficient in terms of height loss. Similar relationships are found for other light aircraft, so 45° is the usually accepted optimum bank angle for least height loss and smaller diameter. The POH may recommend otherwise if high-lift devices are fitted. There is a problem with choosing and maintaining a particular bank angle, in that if the aircraft is not equipped for flight in instrument meteorological conditions there is no reliable instrumental means of accurately assessing the bank angle — though fortunately pilots tend to overestimate (rather than underestimate) the steepness of the bank by perhaps 10°, i.e. they believe they have 45° bank but in reality it is perhaps only 35°. The angle can only be confidently established by comparing the horizon with ascertained structural or cockpit angles. 6.6.4 Turning-back A possible scenario Imagine a competent aviator who has practised for steep turn-backs (at a safe height and maximum weight) and can hold the aircraft at constant speed with a constant bank angle known to be 45° and, by trial, has established the average rate of sink in such a turn. Vsi for the aircraft is 40 knots CAS and Vbg is 60 knots CAS. As a result, the pilot feels comfortable using an airspeed that is only 10% greater than the stall speed in a 45° banked turn — that speed is 52 knots and thus the average turn diameter is 135 metres, rate of turn is 21°/sec, and rate of sink is 900 fpm or 15 feet per second. Suppose that pilot takes off towards the north on a 600-metre north-south strip sited in rough terrain; there is nil wind and smooth ISA sea level conditions. The aircraft lifts off 200 metres from the southern end, climbing away at 60 knots (30 m/sec) and 500 fpm. The engine fails 60 seconds after wheels-off when the aircraft is 500 feet above airstrip level and 1800 m from the lift-off point, or 1400 m from the northern threshold. The pilot takes 4 seconds to react to the engine failure (see 'Engine failure after take-off') and decides on a turn-back. A further 5 seconds passes before the aircraft is established in the glide at the speed appropriate for the turn, i.e. 52 knots. The slow speed roll rate is around 15–20°/sec, so another 2 seconds passes before the turn is established. Thus about 10 seconds elapses between engine failure and start of turn. During this time the aircraft moves about 250 m further from the airstrip and loses perhaps 50 feet of altitude, so at start of turn the aircraft is 450 feet above runway level and 1650 m from the northern threshold. With a turn rate of 21°/sec and sink rate of 15 feet/sec, the 210° turn takes 10 seconds during which the aircraft loses 150 feet. So after straightening up and establishing descent at Vbg, the aircraft is 300 feet above strip level and a bit less than 1650 metres from the airstrip. So the elapsed time from engine failure to being in a position to start the straight line return glide is about 20 seconds, during which 200 feet of altitude is lost while the aircraft has moved nearly 250 m further from the runway. Let's presume the aircraft's L/D is 10:1, so to glide 1650 metres after straightening up it would have to start from a height of 165 m or 540 feet. Starting from only 300 feet it will hit the ground about 750 m short of the runway, so in this scenario the distance to glide after the end of the turn is of more importance than height lost in the turn. If the aircraft had taken off into a 10-knot (5 m/sec) headwind, then the end-of-turn point would be displaced 80 seconds × 5 m/sec = 400 m closer to the threshold, with then 1250 m to run. At the 60-knot Vbg and 70-knot (35 m/sec) ground speed descent the 1250 m would be covered in 36 seconds. The aircraft's L/D is 10:1 so the Vbg sink rate is 6 knots or 10 feet/second. Thus the aircraft will lose 360 feet during the glide indicating that, even with the favourable 10-knot wind, it will hit the terrain 200 m or so short of the threshold. The aircraft might just scrape in for a successful turn-back in nil wind conditions if the initial climb rate was such that it is 750 feet agl at 60 seconds after wheels-off, in which case it would be at 550 feet at end-of-turn. Choosing a safe speed Obviously you shouldn't conduct a low-level turn near the point of stall and any mishandling or turbulence during turns at high bank angles and low speeds may result in a stall-spin event, so a minimum safety factor for the turn must be considered. For a recreational light aircraft a factor of 10% above Vs[turn] may not be enough, so perhaps the turn speed should be 20% greater; i.e. 1.2 times Vs[turn]. For the example in the preceding scenario, that safer airspeed at the required 45° bank would then be 58 knots CAS — which might increase rate of sink from 15 to 17 feet/sec, the turn time from 10 to 11 seconds and thus the height loss in the turn from 150 to 190 feet; acceptable, considering the added safety. However, the stall speed at 45° bank is 1.2 × Vs1 CAS and multiplying that by 1.2 provides an airspeed of 1.44 × Vs1 CAS — close to our normally recognised safe speed of 1.5 × Vs1. So then considering all the inaccuracies inherent in flight we come back to 1.5 × Vs1 CAS (60 knots in the scenario) as the optimum speed in the 45° banked turn-back manoeuvre. Extract from an RA-Aus fatal accident report: 'Following the loss of power at approximately 300 feet, the pilot apparently attempted a turn to the left in an attempt to return to the runway that he had just departed from. At a position approximately 200 metres to the left of the extended centre line of runway 30 and 400 metres from the upwind threshold of that runway, the aircraft entered a spin and impacted the ground in a near vertical attitude. Note 3: In the preceding tables and text I have used the calibrated airspeed but the velocity in the equations should be the true airspeed, so the turn diameter will be greater than shown, the rate of turn will be less and consequently the height lost during the turn will be greater. 6.6.5 So what's the verdict? From the foregoing you might conclude that it would be foolish to state (though many do) that a return to the runway is possible if a particular aircraft type is above a certain height when EFATO occurs. The main factors to be considered/estimated in the very few seconds available for an informed decision are these: The distance you are from the nearest runway/airstrip threshold and the distance you will be when the 45° bank re-positioning turn, flown at 1.5 × Vs1 CAS, is completed and the aircraft established at Vbg. The estimated height still in hand after the repositioning turn is completed and whether that will be sufficient for the glide approach to the threshold. The effect wind and turbulence will have on the result. Although EFATO operations are near ground level the effect density altitude will have on the result must be taken into account. For example, as TAS increases with density altitude then the height loss during the turn at a particular CAS must increase. The existence of obstructions along the glide path. Possible collision avoidance risks in the contra-traffic landing — emergency, low-level, non-powered manoeuvring may lead to a stall/spin event. If very close to the airfield, can sufficient height be lost to land reasonably safely, taking wind effect into account. All of this indicates that the possibility of success is very difficult to assess quickly when airborne time remaining is rapidly counting down to zero. You must know your aircraft and your capabilities, and have previously established the safe turn-back performance under varying conditions. Also you must be a very good judge of distance (few pilots are) and be able to maintain absolute control at rather low energy levels and higher wing loadings; otherwise — it is most unwise to turn back! STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

Once airborne, naturally any engine failure is a failure after take-off even if the aircraft is 100 nm from the take-off point. However, the EFATO term is usually accepted to mean a significant loss of thrust occurring while the aircraft and pilot are still in 'take-off or go-around mode'. For example, haven't yet set course, or raised take-off flap, or haven't yet reached 1000 feet agl if intending to operate above that height, or, if doing circuits have not yet completed the crosswind turn; i.e. a 'thrust deterioration at take-off' that occurs while climbing soon after lift-off or during a go-around when the aircraft has little energy to trade. This module presumes the reader is familiar with the contents of the earlier 'Don't stall and spin in from a turn' and 'Don't land too fast in an emergency' modules, which are pertinent to this document. 6.5.1 What happens when the engine or propeller fails in the initial climb? Pilot and aircraft reaction times A recreational light aircraft established in the climb attitude at Vy (best rate of climb speed) has an aoa perhaps around 6–8°. At such angles there is significant induced drag so when thrust is lost, for any of a multitude of reasons, the aircraft may rapidly decelerate to stall speed — worse if the airframe also has much parasitic drag. The immediate action required is to convert the potential energy of height to a safer speed. When climbing at Vx (best angle or emergency climb speed) aoa could be around 8–12°, so deceleration following power loss is a greater hazard. Of course recreational light aircraft Pilot Certificate holders are aware of this and take immediate action to lower the nose to a position consistent with their estimate of the approach or glide attitude in pitch. Or do they? Material developed by the late Mike Valentine, the former RA-Aus Operations Manager and prestigious GFA stalwart, is included in this section. Mike conducted considerable research into pilot and aircraft reaction times following cable breaks in winched glider launches and engine failure after take-off in recreational light aircraft. Some research results — which were very similar for both aircraft categories — were published in the June 2004 issue of the RA-Aus journal, and are summarised as follows. Following an engine/propeller failure in the climb, there is an initial delay while the pilot's brain adjusts to the shock of the event and then she/he pushes the control column forward. This reaction time appears to average around three to five seconds, much longer than might be imagined, but similar results are obtained in tests by other aviation bodies. Mental paralysis/disbelief, i.e. 'this can't be happening?', is the main contributor to that delayed reaction; meanwhile the aircraft is slowing at perhaps 2 to 4 knots per second. It can be exacerbated by slight panic if the power loss is accompanied by very unusual engine noises, smoke and/or violent shaking. A quiet breakdown in the propeller speed reduction unit results in the unloaded engine's rpm increasing while the propeller is 'freewheeling' — producing no thrust — and it may take a little longer for the pilot to realise what has happened. If the aircraft is equipped with an effective elevator trim system and the pilot has trimmed for the climb speed — which is generally similar to the best glide speed — then the aircraft will of course try to regain its trimmed speed when thrust decreases; however, this takes too long to stabilise, and the pilot must take firm control and push the stick forward. As the pilot pushes over into the glide attitude the aircraft follows a curved flight path. During this manoeuvre, pitch attitude and wing loading are changing, and the aircraft still slows for two or three seconds before accelerating. When the desired attitude is eventually attained, the pushover is terminated and the aircraft is then apparently stable in its glide attitude. Apparently? Yes because, although the aircraft is in the required nose low attitude, it has just been through an energy-changing manoeuvre without the benefit of thrust to sustain it. Its inertia, aided and abetted by its drag, prevents it from immediately attaining the airspeed appropriate to the glide attitude; some seconds must be allowed for the aircraft to build to that speed. Gravity alone can't instantly accelerate an aircraft to a safe speed through a 10 or 15 degree pitch attitude change. The real EFATO event will be noticeably different from that experienced in a simulated EFATO because there is no residual thrust from an idling engine. If the propeller is windmilling there will be additional drag and thus a bit steeper descent path. Also the lack of a cohesive propeller slipstream over the tailplane will make the elevators feel different — and less effective. Any attempt to start manoeuvring the aircraft without allowing sufficient time for the indicated airspeed to build to, and stabilise at, a safe speed will risk loss of control — and don't think there is a discernible lag in the ASI; there isn't if it is in good condition and the pitot-static system is unobstructed. If the pilot lowers the nose to the glide attitude and immediately performs just a moderate 'bank and yank' manoeuvre, the aircraft may stall and spin. At least five seconds will elapse from the moment the pilot pushes the stick forward to the time the airspeed margin over stall is safe enough to carry out a gentle manoeuvre. The diagram below represents the result of Mike's tests in a simulated (and placid) EFATO when climbing at 55 knots (about 1.3 Vs of 42 knots). Similar results were found in other tests. The diagram doesn't show the 3–5 seconds reaction time for the average pilot, as the pilot for the test series was conditioned to an expectation of the throttle being pulled by the observer. During the pushover, the control column was pushed forward smartly enough and far enough to unload the wings to perhaps 0.5g or less, so that the aircraft is still totally controllable even if the airspeed reduces below the normal Vs1 of 42 knots. At 0.5g the airspeed will build relatively quickly because the lift will be nearer zero and thus induced drag is reduced to nearer zero. Unloading the wings is a good practice to practise As mentioned in the flight envelope section of the 'Don't fly real fast' article a light aircraft can be safely held at sub-Vs speeds for several seconds by unloading the wings so that the aircraft is operating in the reduced-g band between zero g and +1g, but not in negative g. The stall speed between +1g and 0g is still proportional to the square root of the wing loading g ratio, as indicated in Table 4.1. Table 4.1: stall speeds at positive loads below +1g Load factor Square root Stall speed knots +1g 1 42 +0.75g 0.86 36 +0.5g 0.70 30 +0.25g 0.5 21 0g 0 0 Note: when the wings are unloaded, ailerons and rudder can be used in ways that would be regarded as excessive at 1g loads. This unloading technique also has value as a stall recovery exercise (at a safe height) for pilots to really comprehend what is going on. It involves unloading the wings to perhaps 0.25g by pushing sufficiently forward on the control column so that you feel very light in the seat but not yet constrained in the harness as you would be if imposing negative g — or if dirt and dust start floating up from the floor. When unloaded — which takes an instant — roll the wings level (holding near zero g of course) using full aileron and whatever rudder is necessary (often quite a lot), and centre the aileron and rudder as soon as the wings are level. As drag at that minimum aoa is much reduced, speed will build more quickly and thus dive recovery is started earlier. With practice, the total height loss by taking such decisive action may be less than in a gentle reaction, and the speed will stay well within the allowable envelope in most recreational light aircraft. There will not be any fuel system problems as long as negative g is not applied. However, if forward pressure is slightly relaxed and the aircraft allowed to return to its normal 1g state while airspeed is below Vs1, the wing will promptly stall. 6.5.2 Practice good energy management in the take-off! Planned energy management during the initial climb Following engine failure in the climb, the total energy available is the sum of kinetic energy and potential energy of height. As shown above, a lot of that kinetic energy is lost to drag in the 6–8 seconds following loss of power. The potential gravitational energy must be converted to kinetic energy so that the total energy level of the aircraft is maintained, albeit at a lower level than that immediately prior to the power loss. There may not be enough time available to regain enough speed within the remaining height to have sufficient energy to arrest the rate of sink (i.e. flare) for a normal landing. A heavy or very heavy landing is then almost inevitable. For example, the low-momentum Thrusters and Drifters have thick high-lift wings that give their best climb rate [Vy] at about 50 knots. They probably need about 150 feet to build enough airspeed to enable the aircraft to be flared for a normal landing; obviously, more slippery aircraft need less height. The solution to this potential problem is planned energy management during the initial climb. Don't use the recommended speed for best rate of climb, use a climb speed perhaps 10–20% higher until at 200–250 feet, then steepen the climb a little to maintain Vy. The loss of initial climb performance won't be particularly significant but the additional speed in hand will make a difference if you lose thrust at a critical height. Of course, you may prefer to maintain the higher speed as a cruise-climb speed, particularly if there is a reasonable headwind or a tendency to overheat. What about using the best angle of climb speed for initial climb? Vx should not be used in normal operations — it should be regarded as an emergency climb speed. The high pitch attitude, high aoa and low speed provide a very limited safety margin if power is lost. If an airstrip is so marginal that you consider you must use Vx to clear obstructions at the end of the strip — or worse, out-climb rising terrain — then you should not be using that airstrip. If you absolutely have to use Vx for obstacle clearance then lower the nose to a safer climb speed as soon as possible. 6.5.3 Always be ready to implement plan B! Have a mental 'what if?" action plan Pilots must always be prepared for the possibility that the engine/propeller will lose thrust during the take-off and climb out (or at any other time during flight), and have simple pre-formulated mental action plans for the particular airfield/strip/runway conditions and various failure modes — remembering that, depending on height if the engine fails, there may be little time to do much else but keep your eyes outside the office, select the landing run and fly the aeroplane. One thing though — it is important to close the throttle early enough to avoid the engine suddenly regaining full power at an inopportune time; e.g. just as you are about to flare, thus driving the aircraft into the ground — which has happened on occasion. If there is any thought that something is not quite right during taxying, run-up or the take-off ground roll, the flight should be abandoned immediately. A surprising number of pilots disregard indications/warnings that something is not as it should be and press on to an inevitably expensive reminder that engine/fuel/propeller problems cannot fix themselves. It'll be okay? Not likely! On-field landing If the aircraft is very low when the engine fails the only option is to keep the wings reasonably level, the slip ball centred and land more or less straight ahead. So the minimum action plan would be: If loss of thrust or other problem is evident, immediately push over into the approach attitude while keeping the slip ball centred. If loss of thrust is accompanied by extreme vibration or massive shaking of the aircraft (possibly due to a propeller blade failure), it is important to immediately shut down the engine to avoid it departing from its mountings. Do nothing else while waiting the few seconds for the aircraft to stabilise at a safe speed — except hold that attitude, keep your eyes outside and decide the landing run; probably there will be little time or opportunity to conduct any cockpit or radio drills prior to touchdown. Ensure the throttle is closed, lower full flap or sideslip if height permits, then land the aircraft. Be careful to avoid wheelbarrowing. Brake hard and/or ground loop if necessary to avoid collision. The groundloop is induced by booting in full rudder (and brake) on the side to which you want to swing and will probably result in some wing tip, undercarriage and propeller damage, unless you impact something other than the ground. Running it into long grass will help slow the aircraft. There have been occasions, even at small airfields, where a recreational light aircraft losing power at 200 feet or less had sufficient height to safely turn 60–90° and land on, or parallel with, an intersecting strip. Of course, the pilot in those reported cases has been quite familiar with the aircraft's capabilities and had commenced take-off with little or no runway behind. Off-field landing If some height has been gained but there is no possibility of landing on the airfield, then an off-field landing is mandatory. Look for somewhere to put it down but don't immediately fix on the first likely landing site spotted straight ahead of you — there may be a more suitable site closer. However, you have to rapidly assess your height and airspeed (i.e. your energy level), and the turn possibilities available; i.e. can you safely turn through 30° or 45°, perhaps 60°, and still make it to that much better looking site? Will the wind assist or hinder? How much height will be lost in the turn? It has to be a quick decision because at best you have just a few seconds available to plan the approach. If any doubt go for 'into wind' and remember you can't stretch the glide! Do not choose the site at marginal distance, even if it's perfect. Close by is better because the height in hand can be used for manoeuvring the aircraft into the best approach position. Because you have no power available you must always have an adequate height margin to allow for distractions, misjudgements, additional loss of height in turns, adverse wind shifts, sinking air, turbulence and other unforeseen events — and you can dump excess height quickly using full flap or sideslipping. Remember that the rate of sink whilst sideslipping is high and the slip must be arrested before the flare. Some major factors affecting the outcome of a forced landing are highlighted in the previous module 'Don't land too fast in an emergency' and it is not my intention to list all factors that might be assessed in the decision making process following EFATO. Suffice to say, it is impossible to assess everything in the few seconds available, hence the need for prior knowledge of the airfield environs, plus a pre-established plan B and intuitive procedures for any situation that may occur before you are established at a safer height. Apart from being clearly within range the choice of landing site is affected by: wind strength and direction ground run availability and direction; a short into-wind site may be preferable to a longer but crosswind/downwind site for an aircraft with a low stall speed; the reverse applies for an aircraft with a high stall speed. It all relates to kinetic energy and stopping distance approach obstructions; final approach may require some diversion around/over trees, under/over power-lines plus avoidance of other obstructions. Can the near-ground turns be handled safely? Is there sufficient margin for misjudgement and/or wind gusts? ground surface and obstructions, including livestock, during the ground roll. Can you steer to avoid them? Are livestock or kangaroos likely to take fright and run into your path? the energy absorbing properties of the vegetation ground slope: the possibilities of landing downslope may range from difficult to impossible; moderate upslope is good if the pre-touchdown flare is well judged. There is a much greater change in the flight path during the flare; for example, if the upslope has a one in six gradient (about 15°) and the aircraft's glide slope is 10° then the flight path has to be altered by 25° so that the aircraft is flying parallel to the upslope surface before final touchdown. A higher approach speed is needed because the increased wing loading during the flare (a turn in the vertical plane) increases stall speed. If the wind is upslope then a crosswind landing may be feasible if a rural road is chosen can you avoid traffic, larger trees, drainage ditches, wires and poles, particularly in a crosswind situation? a final approach into a low sun should be avoided so that vision is not obscured. All of this is impossible to assess in the few seconds available, hence the need for prior knowledge of the airfield environs and a pre-established emergency procedure for any situation that may occur before you are established at a safe height. As height increases, the options increase for turning towards and reaching more suitable landing areas, making a short distress call and doing some quick trouble shooting. Trouble-shooting When trouble-shooting full or partial power loss remember the first edict — constantly 'fly the aeroplane!'. If the engine is running very roughly or died quietly (i.e. without obviously discordant sounds associated with mechanical failure) and time is available, then apart from the engine gauges, the obvious things to check or do are: Fuel supply: switch tanks (making sure you haven't inadvertently switched to the 'fuel off' position), fuel booster pump on, check engine primer closed. Air supply/mixture: throttle position and friction nut, throttle linkage connection and mixture control position. Apply and maintain carburettor heat (while engine is still warm), setting the throttle opening at the normal starting position. Apply carburettor heat or select alternate air to bypass the air intake filter — which could be blocked by grass seeds or a bird strike. Ignition: position of ignition switches — and try alternating switches in case one magneto is operating out of synchronisation. Or: reverse the last thing you did before the engine packed up. And then: try a restart. There is no point in continuing with a forced landing if the engine is really okay. Cockpit check prior to touchdown Pilot and passenger harnesses must be tight and maybe remove eyeglasses. Seats should be slid back and re-locked in place (if that is possible without adding to the risk) but be aware of the cg movement. Advise the passenger of intentions, warn to brace for impact and advise evacuation actions after coming to a halt. Unlatch the doors so that they will not jam shut on impact. If the aircraft has a canopy or hatch take similar safety action, if that is possible without the canopy affecting controllability or detaching and damaging the empennage. If equipped with a retractable undercarriage, leave the wheels down unless surface conditions indicate otherwise. To minimise fire risk turn the ignition, fuel and electrics off. It is important to research and develop your own safety plan, including the cockpit and radio drills, so that it is more deeply ingrained and appropriate to your capabilities and the aircraft being flown. Don't just adopt a plan published by someone else. Before moving onto the runway for take-off, do a mental rehearsal of plan B; such rehearsal is a powerful safety aid. As height achieved before engine failure increases, the options increase for trouble-shooting, turning towards and reaching more suitable landing areas; making a distress call on a selected frequency; properly securing the fuel, ignition and electrical systems; and for an adequate cockpit check prior to touchdown — but all in accordance with the plan. Partial thrust loss If the engine/propeller does not fail completely but is producing sufficient thrust to enable level flight at a safe speed then, if you can't determine the fault, it may be possible to return to the airfield. Make only moderate turns, maintaining height if possible without the airspeed decaying, and choose a route that provides potential landing sites in case the engine loses further power. It's a judgement call whether you should take advantage of a possible landing site along the way because the off-field landing may damage the aircraft and perhaps injure the occupants. But that must be weighed against the chance of further power loss producing a more hazardous situation; it is usually considered best to put the aircraft down at the first reasonable site. If there is insufficient power to maintain height, then of course you must set up an off-field landing. Intermittent power If the engine is producing intermittent power, and you can't determine the cause using your Plan B trouble-shooting schedule, it is probably best to use that intermittent availability to get to a position where a glide approach can be made to a reasonable off-field site. Intermittent power negates the ability to conduct a controlled approach and could get you into a dangerous situation. So having achieved a position where you can start a final approach, then secure the engine by shutting down the fuel, ignition and electrical systems. Securing the engine early means it will be colder at touchdown, reducing fire risk, but it mainly gets that job out of the way so you can concentrate on flying. STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)