Training for flights over water, but close to the coast

[farri]

I can see that there are situations where you may want to minimise the decent rate, but certainly for the last 100' feet or so I'd want a bit of speed in hand to manage the flare

Absolutely!

 

No matter which AC it is, it`s only the impact with the ground or water that realy hurts and the best way to impact real hard is to allow the airspeed to be too low!

 

Frank.

 

 

[.Evan.]

it`s only the impact with the ground or water that realy hurts and the best way to impact real hard is to allow the airspeed to be too low!

Isn't that the point, though? Impacting the ground at the slowest speed possible at the end of the flare/hold off - it's reaching too slow a speed too high above the ground/water that is the problem, isn't it?

 

 

[farri]

Isn't that the point, though? Impacting the ground at the slowest speed possible at the end of the flare/hold off - it's reaching too slow a speed too high above the ground/water that is the problem, isn't it?

I take Spins post to mean that he wants enough speed for the last 100 feet, so that he can avoid stalling and flare sucessfully.

 

If we only look at the moment of impact, then of course, the slower the speed the softer the impact!

 

Frank.

 

 

[jerrajerra]

That's interesting, I assume this is in the 172?This is from my C172 POH

 

[ATTACH=full]14950[/ATTACH]

 

I believe he's talking about the same type aircraft, though I could be wrong.

Yes, it is the same AC. My co-learner concurrs the training method being applied by our FI. He was verballed because he was doing less than 70kts on decent and was instructed,"....i don't want to see that again. I want to see 80!" But then of course one would need to be at a slower but definately controllable speed at the point of flaring/ditching that machine on water. The altitudes we were training at were at varying heights, at 1,000ft to 3,500ft

 

 

[Tex]

" The normally quoted "best" glide is for distance, not for min descent rate. If distance is not an issue and you want minimum descent, a slower speed than best glide will provide this."........????what is this ..."if distance is not the issue"...stuff about??????....whats this "minimum descent"...stuff about?????

 

surely 'minimum' descent..(what ever that is)...is the warm and fuzzy feeling u have immediately before the a/c stalls and enters a spin......

Not at all, that is a fundamental misunderstanding of speeds to fly. Min sink is NOT at stall nor is it necessarily anywhere NEAR it. Yes it is slower than best L/D or approach speeds, but not so slow as to stall.

Simple scenario as example... engine failure at height of say 3000', set best glide speed, just for arguments sake lets say sink rate is 500fpm (nice!) you have 6 Min till touch down, if perchance you hit an energy line or thermal etc on that glide and your sink rate goes to 400fpm (net 100fpm lifting airmass at that airspeed), then select min sink speed you might get 300fpm or BETTER depending on the normal parameters between best L/D and Min sink speeds. That would give you and extra 4min of airtime - 66% more (if you hit it straight away and had good air the whole descent - unlikely). If you just maintain that for 1 minute you have nominally gained 200ft over the same time cf best L/D. Return to best L/D if required. Below say 500' you should most certainly be in 'circuit' mode. Of course it still all relates to what you are trying to achieve; make it too a spot to land; get more time to think about it etc. Then there is wind to think about as well.

 

Another simple scenario... you have an engine failure, select best glide as you need to MAKE that one and only spot, but you might not get there... then a little better sink rate appears on the vario, select best sink, two fold result you are in the 'better' air longer (as you are slower) and have a better sink rate for a time giving you a greater chance of making it than you had than just sticking with best L/D. Tough return to best L/D when the sink rate gets worse again.

 

In any case, this knowledge of speeds to fly could gain you just enough to make a real difference in an emergency. Really only applies with some altitude though... then again maybe good for use at any stage.

 

 

[Tex]

i regularily achieve 'minimum descent'..immediately prior to touchdown.

 

 

[rgmwa]

what is this ..."if distance is not the issue"...stuff about??????....whats this "minimum descent"...stuff about?????

Rule of thumb - best glide speed is about 1.4 x Vstall. Min sink speed is about 1.2 x Vstall.

 

rgmwa

 

 

[damoski]

There are lots of good suggestions, but how many can you execute in a panic, in 40 seconds or so?

 

I'm not keen on a >60 degree bank and dive without power to effect a sharp change of direction - it's a nice idea, but only one I would consider trying if I had hundreds of hours under my belt and had absolute confidence that I could perform such maneuovures with zero mistakes, even in times of high stress. I hope to be that good one day!

 

For my part, the steps I would rely on would be:

 

- Wear lifejacket, brief passenger, tighten seatbelts, read ahead for beach/out landing possibilities

 

- Keep updating current position in your mind (eg. "victor1 Bondi beach"), so you can immediately declare it without having to think. Hopefully not a problem on a scenic flight!

 

- on engine failure, do a double take. Feel adrenalin kick in. Start a gentle turn towards landing site or shore if viable, assume best glide

 

- meanwhile, broadcast mayday, call sign, location, pob - maybe repeat the location

 

- Crack open doors if appropriate

 

- ensure pax is in brace position

 

- aim for beach if an option and empty; shallows alongside boats or swimmers if not

 

- use flaps, then heavy flare, to touch tail first at minimum velocity

 

- cover face instinctively, maybe draw back feet?

 

- get out

 

Also - no-one has mentioned attempting a restart? I guess I would feel it's unlikely to help - whatever caused the engine to stop (assuming you've nervously checked Ts&Ps and fuel before flying over the coast) is unlikely to be resolved by turning gar ignition, and there's no time for it.

 

I've only had 2 major scares that I can think of in my life: one was coming off a motorbike at 110kph, and the other was being caught in a crumbling building in a major earthquake. The first taught me that accidents can happen so quickly as to make the best intentioned plans unachievable, and the second was it's all well and good planning to duck under tables or in doorways because the survival stats indicate that's the best course of action, but human nature is to run in fear for the nearest exit and screw the advice. Now.... In flying we do have some amount of time in which to use the training we've had drummed into us, but I would really still want to try to stick to a simple plan that closely aligns to my survival instinct!

 

D

 

 

[Spin]

There are lots of good suggestions, but how many can you execute in a panic, in 40 seconds or so?D

:thumb_up: hit the nail on the head. There are enough vital actions to be performed before making a controlled landing on the water, without cluttering your thinking with a bunch of other considerations.

 

 

[rgmwa]

Another tip I read about from a couple of ferry pilots who survived separate ditchings. If the aircraft is upside down or underwater, once you're out, don't try to swim to the surface. Disorientation can mean you try to swim in the wrong direction. They did initially. Therefore once you're out and clear of the aircraft, inflate your vest or let your own bouyancy carry you in the right direction. (Alternatively follow the air bubbles?). No doubt easier said than done if you find youself underwater unexpectedly, but sounds like good advice.

 

rgmwa

 

 

[Spin]

http://www.equipped.com/aopa-ditch-rebut.htm

 

Following on from the Paul Bertarelli article posted by Mozartmerv in the accompanying thread, I found the story above amusing - reminds me that it isn't only on recflying that pilots all but come to blows in support of their pet theory. It does explain how some of the firmly held opinions/myths(?) originate - eg high wing aircraft will almost inevitably go over on their backs.

 

Sad that someone had to die to bring all this to light, but a refresher course on the available material makes me feel a whole lot better about doing the Cape Moreton - Redcliffe jump as well as low level past the Gold Coast; should the worst happen, there is every chance that I and my passengers will make it out ok.

 

 

 

 

 

[biggles]

http://www.equipped.com/aopa-ditch-rebut.htmFollowing on from the Paul Bertarelli article posted by Mozartmerv in the accompanying thread, I found the story above amusing - reminds me that it isn't only on recflying that pilots all but come to blows in support of their pet theory. It does explain how some of the firmly held opinions/myths(?) originate - eg high wing aircraft will almost inevitably go over on their backs.

 

Sad that someone had to die to bring all this to light, but a refresher course on the available material makes me feel a whole lot better about doing the Cape Moreton - Redcliffe jump as well as low level past the Gold Coast; should the worst happen, there is every chance that I and my passengers will make it out ok.

 

[ATTACH=full]14964[/ATTACH][ATTACH=full]14965[/ATTACH][ATTACH=full]14966[/ATTACH]

Spin ,

I did that VFR route from just North of YCAB across Moreton Bay toward Tangalooma then down the Western side of both Moreton Is. and Stradbroke Is.last week , and are presently enjoying a few weeks on the Gold Coast before returning to Victoria. It is all done below the 3500'step and there are several options in the event of an engine failure and on a good day very scenic . I personally would not do Victor 1 in any single engine a/c. I did not continue down the Gold Coast where the recommended flight levels are 500 & 1000' but tracked over Sanctuary Cove into Southport .

 

Bob

 

 

[Guest Howard Hughes]

what is this ..."if distance is not the issue"...stuff about??????....whats this "minimum descent"...stuff about?????

I am still waiting for an explanation on how flying below best glide speed (best L/D ratio) equates to a reduced rate of descent? Anyone care to explain? Mazda? Tex? RGMWA? Preferably with a graph/some physics to back it up!

Cheers, Mark (aka HH).:thumb_up:

 

PS: All of the references I can find relate to gliders or hangliders.

 

 

[Tex]

Sure Mark will do... At work until about 9pm then will oblige. In any case the theory is the same for all aircraft (with more variables involved for rotary) gliders, hang gliders, RAA, GA... Do quick search on 'polar curve', everyone aircraft has it's own... Will post some graphs etc later when I get off the iPhone.

 

 

[Guest Howard Hughes]

Thanks Tex! :thumb_up:

 

Work? Don't ya just hate how it gets in the way!

 

 

[Tomo]

Bit like Vx and Vy I suppose

 

:big_grin:

 

 

[rgmwa]

I am still waiting for an explanation on how flying below best glide speed (best L/D ratio) equates to a reduced rate of descent? Anyone care to explain? Mazda? Tex? RGMWA? Preferably with a graph/some physics to back it up! Cheers, Mark (aka HH).:thumb_up:

Here you go, with graphs:

 

http://www.gliderbooks.com/downloads/H_Ch4.pdf

 

rgmwa

 

 

[Litespeed]

It might bear some explanation, but read your Beacon manual... Most don't send a signal instantly to avoid inadvertent SAR registrations. It may be 30 seconds after activation before it actually sends a SAR signal. Further the GPS (assuming it is one with one) has just been powered on in an unfamiliar (to it) location. A GPS can easily take a minute to boot up and establish a location. With mine the test procedure will disclose how long the GPS takes, but remember that the time it takes is dependent on how many satelites it can see and signal strength.It can be hours to narrow the location of a beacon without a GPS, and even then to a significant search area. Read the info on the AMSA web site.

 

Just don't think it all happens instantly.

Thanks for David for the above - even more reason to activate early. I am thinking more of the latest versions of the personal gps epirbs that are expensive but fast. Ie the latest ocean rated ones.

 

Given the aircraft will most likely end up sinking- the onboard unit will be of little use. no signal from 30 fathoms.

 

Often I see guys go fishing in mega dollar boats, $1000 fishing reels etc but refuse to buy a top line epirb and go the cheapy models at half price.

 

They have low resolution and make it much harder to be found. The best do it down to a few metres, not a square km.

 

Imagine on a dark stormy night the chance of been found- choose a high model, could save your life.

 

 

[Tex]

a bit like arguing about best range(distance) vs best endurance(time aloft)...from 500' in a glide both would not make much difference..

That is true, not much difference, still very useful knowledge in anticipation that all (if any) of your emergencies may not happen as low at 500'. After all this thread is not about just being at 500'. I have read a few times on this forum "summoned the sum total of his knowledge and skill". When I think coastal I think ridge lift, might not be much, but that extra little puff of offshore wind blowing up a cliff face might be enough to get you around the headland (at 500') to a beach, but do you fly best L/D or Min sink? Just a little more in the memory bank can not hurt to answer that question. I hope you or I never need it in an emergency...

YES, as an aside the knowledge will also help you save fuel too can never have enough of that stuff

 

Here you go, with graphs:http://www.gliderbooks.com/downloads/H_Ch4.pdf

rgmwa

Sorry Mark... what can I say... it is all in here, no point in me trying to repeat it less eloquently:clap:

As I said elsewhere: Gliding is the natural and ordinary state of flight. Just because you add an engine does not change the fact, that at its base level, you are flying a glider.

 

 

[Guest Howard Hughes]

Thanks for the link RGMWA it is very enlightning and just goes to show how much you forget.

 

Now I do have a few concerns, I have never seen a polar curve nor minimum sink speed published (in flight manual) for any aircraft that I have flown. To me this suggests that the difference between published glide speed and minimum sink is so small that it would be almost impossible for us mere mortals to maintain with any accuracy.

 

Should we be advocating flying below 'best glide speed' when the actual figure for minimum sink is not specified? What speed do we fly? Do we need to consider the consequences of flying below minimum sink speed?

 

Now I freely admit that I am not a glider pilot, but when I was younger I did a lot of flying in the US, where the PPL/CPL syllabai is a lot different to Australia. In Australia we do a lot of stalling and a lot of navigation, in the US they do a lot of low speed flight, I have done more short/soft field landings, eights on pylons, pylon eights, lazy eights and chandelles than I care to remember. In all that time no mention was ever made of minimum sink speed, but a lot of the training was spent flying behind the drag curve. What I learned from this was that I never want to be caught in that position with no power.

 

My own opinions aside, it would be fairly simple to work out the minimum sink in a powered aircarft. Firstly fly along at best glide speed and note the power required to maintain altitude. Then fly along 5 knots slower and note the power required to maintain that speed. If the power setting required is higher (which I expect it will be) then the 'minimum sink speed' is between the two speeds. If the power setting is less, then try reducing a further 5 knots and note the new power setting. Using this process of elimination you will be able to work out an approximate minimum sink speed.

 

NB: My advice in an engine out situation would still be to maintain 'best glide speed', this will give you the best range, greater control authority and adequate buffer above stall.

 

Cheers, Mark.:thumb_up:

 

PS: A great article here regarding flying behind the drag curve (aka below minimum sink).

 

 

[Tex]

Thanks for the link RGMWA it is very enlightning and just goes to show how much you forget.Now I do have a few concerns, I have never seen a polar curve nor minimum sink speed published (in flight manual) for any aircraft that I have flown. To me this suggests that the difference between published glide speed and minimum sink is so small that it would be almost impossible for us mere mortals to maintain with any accuracy.

 

Should we be advocating flying below 'best glide speed' when the actual figure for minimum sink is not specified? What speed do we fly? Do we need to consider the consequences of flying below minimum sink speed?

 

Now I freely admit that I am not a glider pilot, but when I was younger I did a lot of flying in the US, where the PPL/CPL syllabai is a lot different to Australia. In Australia we do a lot of stalling and a lot of navigation, in the US they do a lot of low speed flight, I have done more short/soft field landings, eights on pylons, pylon eights, lazy eights and chandelles than I care to remember. In all that time no mention was ever made of minimum sink speed, but a lot of the training was spent flying behind the drag curve. What I learned from this was that I never want to be caught in that position with no power.

 

My own opinions aside, it would be fairly simple to work out the minimum sink in a powered aircarft. Firstly fly along at best glide speed and note the power required to maintain altitude. Then fly along 5 knots slower and note the power required to maintain that speed. If the power setting required is higher (which I expect it will be) then the 'minimum sink speed' is between the two speeds. If the power setting is less, then try reducing a further 5 knots and note the new power setting. Using this process of elimination you will be able to work out an approximate minimum sink speed.

 

NB: My advice in an engine out situation would still be to maintain 'best glide speed', this will give you the best range, greater control authority and adequate buffer above stall.

 

Cheers, Mark.:thumb_up:

 

PS: A great article here regarding flying behind the drag curve (aka below minimum sink).

Valid and worthy considerations... Your method for working out speeds to fly in a powered configuration has merit and would work in that set up .

The best way to work out best glide/min sink if they are not published is to plot your own. In a perfect world that is done in neutral air (neither lifting nor sinking airmass, so sunrise is the best) with the engine off, off course that is not practical (for everyone). Next best would be at idle. All you do is select an air speed (a fair bit above best glide) note sink rate, 5 knots slower, note sink rate etc and plot on graph for your polar curve. Of course spinning prop etc and general air plane config make it all variable.

 

Just selecting A best glide speed is rather pointless as it is a function of wing loading, which changes everything! (The polar curves moves right with more weight). Usually published best L/D should state at what percentage of MTOW, if it is for less than MTOW and then you just select best glide when HEAVY (correction) you are probably actually closer to min sink! Confused yet HAHA

 

Yes default to what you know (if that is all you know), best glide for best range with an engine failure

 

If I am punching along over tiger country (or the ocean) knowledge of this is priceless when best glide still may not be enough to get you to a land-able area.

 

One critical point to make it simpler as as well... any speed between best glide and min sink is a BETTER SINK RATE than best glide. You should be able to fly your aircraft comfortably between to min sink and best glide with out fear of stalling it. If you can't.....

 

 

[rgmwa]

If I am punching along over tiger country (or the ocean) knowledge of this is priceless when best glide still may not be enough to get you to a land-able area.

Meaning, when best glide won't get you far enough, min sink rate will give you more time to realise you're not going to make it.

 

 

[Tex]

 

Need as much time as I could get, I would have a lot to confess If I was coming up 10ft to low to make it over that last tree or breaking wave I would confess I wish I knew more about speeds to fly!

 

 

[Guest davidh10]

Here you go, with graphs:http://www.gliderbooks.com/downloads/H_Ch4.pdf

rgmwa

Curious to see vertical speed measured in knots. Nothing wrong with that, but it isn't very useful when your VSI is reading (feet * 100)/minute. Does anyone actually measure altitude in nautical miles?

 

 

[Tex]

No but sail plane pilots generally use kts, Hangliders and Paragliders used to use fpm but recently there has been a trend (out of Europe) to use mps AND meters for altitude I actually use kph, km, fpm and feet for altitude when hang gliding - but obviously standard units for all powered flying

 

knts to fpm is pretty easy... 1kts x 101fpm

 

knts to mps x .5