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Hello, nice to meet you and I'm sorry for disturbing!

I would like some help from someone with a great experience like you. I'm a private pilot, heading towards my commercial license and I realized that I have some doubts regarding some flight regimes which I don't master on my own. I will try to summarize them below, I hope you could follow and help me.

The first issue I have is about stall and spin in bad weather/turbulence. For example, if suddenly the 15 kts headwind shifts its direction and becomes a tailwind, I will lose 30 kts of airspeed, right? If so, I don't get it if the result would be a stall or just losing lift and momentary have an increased rate of descent. Actually, I can't figure out on my own if the AOA would change even if the pilot maintains the same attitude during the windshear event.

The same problem for updrafts/downdrafts. As far as I know, these gusts momentary change the AOA and thus it would results a stall, right? What if hypothetically just one wing is affected by the gust? The result would be a spin? Or more likely a snap roll? All these scenarios are in the low and slowflight regimes i.e. takeoff/landing, because I guess this would be the most probable scenario to be problematical.

The next problem is about crosswind landings. We use to make stall landings in small airplanes, so, considering this and a kicking-the-crab in flare technique, you are uncoordinated close to stall when you kick the crab and use opposite aileron to prevent banking due to rudder use. How safe is this?

Also regarding stall, is there any difference between an accelerated stall and a dynamic one?

Thanks so much!

Answer
1) ...if suddenly the 15 kts headwind shifts its direction and becomes a tailwind, I will lose 30 kts of airspeed, right?
You won't lose 30kts indicated. Your airspeed indicator is reflecting any headwinds going into the pitot tube or the total air pressure entering the pitot plus HW (versus static calm air in a no wind condition). Take away 15kts headwind from your 100 knots indicated, you will have 85kts indicated. If you now have a tailwind, your airspeed will degrade to indicate 85kts and you will be moving across the ground at 100 kts.

2) updrafts/downdrafts....[will] the result would be a stall or just losing lift and momentary have an increased rate of descent? [Would] the AOA change even if the pilot maintains the same attitude during the windshear event?

Often the effect is simply transient with a fluctuation in speed or altitude. Depending on the windshift velocity, it could certainly affect the angle of attack of an airfoil resulting in a loss of lift leading to a stall or even loss of aircraft control. The latter is more likely with a windshear than just a windshift.

3) The same problem for updrafts/downdrafts. As far as I know, these gusts momentary change the AOA and thus it would results a stall, right?

If you have 15kts of headwind and your windshift occurs during takeoff/landing phases, the resulting loss in indicated airspeed leads to an AOA increase. Yes, that could then lead to a stall if other factors are at play, including poor or no pilot corrective action.

4) What if hypothetically just one wing is affected by the gust? The result would be a spin? Or more likely a snap roll?
While not impossible, I doubt either with early recognition and proper corrective action. A snap roll would require yaw from a sudden rudder input, with opposite aileron, while pulling back on the yoke. If someone applies such full control inputs in gusty weather they are creating a situation for themselves. It seems to me a day of flight training when it's quite gusty out is exactly what you need so you can see and feel what happens and the actions required to truly help you learn. Books and reading can only take you so far. Perhaps you simply need to "do" and not read about it.

5)...kicking-the-crab in flare technique, you are uncoordinated close to stall when you kick the crab and use opposite aileron to prevent banking due to rudder use. How safe is this?

Quite safe. Hundreds of thousands of hours over decades have surely been flown on landing in this manner. In a stiff cross wind, there is no other way to get your aircraft aligned with the runway for touchdown.

Regards,
D.  

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D. Norkus

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I can address questions about airline pilot employment & entry level airline careers in the United States, women pilots, flight training, pilot certification, U.S. flight scholarships (mostly for women), aviation & airline safety topics, aviation accident investigation and airline operations. ***Please note, I cannot address flight training & career queries from outside the United States, or aero engineering degree programs/careers, aviation management topics. ****

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Airline captain with 15 years past experience in airline ground operations. I have previously flown as a commercial skydive pilot & ferry pilot and majored in Aviation Science


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Embry Riddle Aeronautical University; Aviation Safety/Accident investigation

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