what is with the wind lately

[Guest graham campion]

i have been flying for almost 6 yrs and almost 200hrs tt but lately have come across some weird winds,,whilst flying from howlong 2 weeks ago in the middle of no where flat ground nearest hills some 50nm away and at 1500 ft agl,i got hit with cattabatic type winds lost up to 400 ft then 5 mins later got 200 ft lift?

 

an hr before this i was flying with one hand on the bar for an hr and had an hr or these terrible winds to get back to holbrook,it was a case of rest 5 mins bang get hit again tried climbing to 3 thou no difference looked at weather map yes we had a low over us but never exp that before ?

 

did some circuits again wed night with similar low over us but was no where near as bumpy as that sat?

 

i called yywg when i landed and they exp the same winds and were only 20nm from where it all started!

 

any body exp the same or what is the best way to deal with this?????

 

 

[Louis Moore]

I am to far away and was not flying at those times. So it's not wake turbulence from the Auster Graham!

 

I do not think it is necessarily uncommon to run into unexpected patches of rough air, they can be caused by numerous and sometimes seemingly unexplainable reasons. As for dealing with them if there unexpected and not predicted the only real thing to do is simply keep flying the aircraft! If there bad enough and last long enough try climbing or descending out of them.

 

On another note, when it comes to those fun winds that try to pull you down then shoot you back up again I have found the best approach is simply to let the aircraft ride them. It always worked out to be a total waste of time fighting the down and up drafts to try and keep at a single altitude. I would allow the aircraft to slip down through the winds and ride them back up again over and over. Was never usually much more than a few hundred feet of altitude in the ups and downs and flying with them was so much more comfortable!

 

 

[Gnarly Gnu]

These skydive folk got hit by a nasty wind.

 

Meanwhile it's been calm for a good while here, probably too calm.... get no crosswind landing practise.

 

 

[Guest ozzie]

This is the time of year when the jet stream drops. Howling westerlies anything around a hundred knots at 10,000 easing to lower levels. Lose a bit of height then shortly later gain it and a bit more back. Possible standing waves. Mountains or large hills anything up to a hundred k or more away? Flattish or lenticular cloud around mark this. If in this situation and looks like you may not clear rising ground immediately turn 90 deg to track is recommended.

 

It's just winter, wait till late August and September for full effect.

 

 

[eastmeg2]

Hi Graham,

 

Sounds to me like you could have experienced some sheer layer turbulence. Sometimes it's confined to a thin band of altitudes and other times its quite spread out. It's a bit of an art to tell whether bumps are due to thermals, terrain or sheer . . . but learning what to look for can help though sheer is the one that can typically creep up with little or no visual clues and can have ups and downs too.

 

 

[Guest davidh10]

I was thinking of flying early that day, as I had a lunch appointment. After studying the weather at about 0800,it was already 17G23, which in itself would have been Pl, but the trend was strengthening, so I figured I wasn't that desperate to get airbourne.

 

Later in the morning, and through lunch time the wind on the ground got very gusty and swirled around a lot. I lunched at a winery, East of Rutherglen, and the conditions looked to be quite unpleasant for flying.

 

I agree that there have been some quite strange winds recently. I also agree with Louis. You only get tired fighting it. Unless there is reason to do so, like a big down draught on late final, just go with the flow and correct the averages, not the peaks.

 

I have had one occasion where I needed a burst of full power to counteract the increased AoA needed to restore the correct descent rate on late final.

 

 

[facthunter]

In cruise you let it move around but as you come over the fence it is well to have a bit of power on and a few Knots up and be very positive with the controls. IF it is a dirt strip the dust will give you a warning sometimes, that there may be 'twisters " in it. We used to call them '" dust devils" up the Centre . They can bring you undone.

 

When the ground is much warmer than the air mass over it you get "thermally' conditions which make it unstable. High adiabatic lapse rate. Nev

 

 

[Guest davidh10]

Dust devils do make you bite your tongue.

 

 

[Guest graham campion]

Dust devils do make you bite your tongue.

thankyou for the replies ,

sky was crystal blue no clouds but wind just whipped up from ??????

 

didnt need super glue to hold me to the seat lol,,,

 

but the track back to holbrook some 30nm was not pleasent just had to sit there and ridewith it,,oh well one for the story book,

 

dave ,

 

peter mentioned he had trouble as well ,,,

 

same highs and lows?

 

 

[Guernsey]

I would allow the aircraft to slip down through the winds and ride them back up again over and over. Was never usually much more than a few hundred feet of altitude in the ups and downs and flying with them was so much more comfortable!

I used to fly an Auster years ago and found that the Auster just loves to fly on its own, ride the waves and generally have a good time without any input from me.

 

Long live the AUSTER.

 

Alan.

 

 

 

[Louis Moore]

Mine was built in 46 and still going strong, so there hard to kill Alan!

 

 

[Clansman]

Experienced my roughest ride in 10 years returning from Natfly last month between Swan Hill and Murray Bridge, just had to go with the flow, slow it down a little. It's bloody annoying when forecasts look steady and stable and you have 2-3 hours flying to go.

 

One piece of knowledge many pilots don't appear to understand is how small a vertical wind shear can negate your climb rate. Our VSIs read in 100' increments and most of our types can climb at 500' - 1000' per minute, some maybe 1200 fpm. Have you ever converted these to knots? One knot is 1nm per hour or 6080' per hour, keep it simple and call it 6000' per hour, which is 100' per minute. This means if your best climb rate is 1000 fpm which is only 10 knots, a downdraft of 10 knots will completely eliminate your actual climb relative to the ground, and bingo! You run straight into whatever you're trying to clear, despite maximum throttle and best climb attitude.

 

We're inclined to think that forecasts of 10-15 knots are perfect flying days with little risks, but a little mechanical rotor over an obstacle can turn that 10 knots into an equivalent wind shear enough to push you into the obstacle by negating your climb ability.

 

Most people equate such risks only with CB thunderstorm type winds where 30-50 knots are common, but don't be fooled into complacence and therefore danger.

 

Next time you read your VSI think of the 100 fpm increments as 1 knot and it might save you some grief. And on those rough days cross country, those pot holes you keep hitting are probably not more than very small changes in vertical wind component of 2-3 knots at most.

 

Stay safe and have fun.

 

 

[Guest davidh10]

Very true and a good thing to point out. I have reasonably often encountered 500-800'/min up/down draughts, so I think your 2-3kn is a little understated.

 

Just as an exercise, calculate the change in AoA when entering a column of air that is moving vertically in the range above. People may be surprised at the results.

 

 

[Clansman]

Absolutely David, My 2-3 knot pot hole analogy is just that, the rough bumps that make flying unpleasant but not dangerous unless you exceed max maneouvring speed in turbulence. Those 500-800 fpm moments you mention make it hard to hold accurate altitudes, are awkward in the circuit and dangerous on late final.

 

Good point about AoA, never thought about it like that before. I reckon if you're doing 60 KTAS and encounter vertical shear of 100 fpm or 1 knot, then your AoA would alter 1 degree based on the old 1 in 60 rule. So if you copped 1000 fpm (10 knots) the AoA would increase by 10 degrees. If you fly at around 3 degrees AoA straight and level normally then your AoA would therefore reach 13 degrees which approaches the 16 degree stall angle. Need to think about it - anyone else?

 

 

[Guest davidh10]

Yep. I did it trigonometrically, and it does indeed approximate 1 degree per 100'/min for an aircraft doing 60 KTAS.

 

Now suppose you aren't in cruise, but throttled back a bit in the circuit, with a higher AoA. You are now more susceptible to momentary stalls due to vertical wind gusts. Of course it only lasts until the aircraft's inertia is overcome and it accelerates in the direction of the gust, unless of course it does stall and then its acceleration in the direction of the gust (upward), is counteracted by the aircrafts downward force due to gravity, which is no longer balanced by wing lift. It is now likely that the aircraft will actually descend against the gust direction, thus further increasing the effective AoA.

 

I have encountered this on one occasion when turning base on a very rough day and the wing stalled during the bank as it was hit by a gust. My instinctive reaction was to reduce AoA, and flight was restored in probably one or maybe two seconds. It was that experience which prompted me to do the calculation, just to increase my understanding.

 

Imagine, however a misjudgement where the pilot, due to the aircraft losing altitude believes it is a down draught and increases AoA to compensate... Just another reason it is very important to know what a stall feels like.

 

 

[Clansman]

Great points David - I've now got something new to add to my stall discussions with students!