The date is set.

[3WE]

Are you guys suggesting that 'almost all professional pilots' have encountered an unexpected stall and flown out of it? God I hope not.

The fact is we really have no idea how many professional pilots are prepared to deal with that.

I would say that most pilots have encountered an unintended stall. My example came from a secondary stall- and in my case it was a full stall with a nice little uncommand roll added in. [Very recently saw a YouTube of professional dudes practicing full stalls in a 737 sim...on recovery the stick shaker kicked back in...I think they caught it just short of the second stall]

Much like Gabriel (and thanks to my instructor's PRIOR instruction (he was not there) and some outside reading) I instinctively knew what to do even though the aircraft surprised and scared me. And fortunately, I was at a safe altitude and made immediate corrections- lost a couple hundred feet doing a robust recovery.

And all of this done as a highly-experienced 30-hour veteran flying a 2000-pound airplane with a handful of levers to manage throttle, carb heat and mixture...

I could be wrong that "most" pilots have seen this- but I do think it's more often than you think it is. For folks who have flown a single-engine Cessna, there's a significant likelihood you have heard a stall warning during the landing flare. Maybe Bobby or Brian will chime in.

[Evan]

Gabriel (and almost all pilots but not enough) have proven that this can be overcome with knowledge and discipline, so that's what we are doing.

Are you guys suggesting that 'almost all professional pilots' have encountered an unexpected stall and flown out of it? God I hope not.

The fact is we really have no idea how many professional pilots are prepared to deal with that.

[Gabriel]

Gabriel (and almost all pilots but not enough) have proven that this can be overcome with knowledge and discipline, so that's what we are doing.

Fixed.

Fixed.

[3WE]

Gabriel (and almost all professional pilots) have proven that this can be overcome with knowledge and discipline, so that's what we are doing.

Fixed.

[Evan]

In pretty much all modern not-automated-to-death aircraft (sorry Airbus), the nose will drop when the plane begins to stall (sometimes one wing, sometimes both, but either way the nose drops). If pilots are being trained to hold attitude when that happens, they will pull back on the stick/yoke. Because when the nose is dropping, how else do you raise it? Pulling on the controls to make the nose go up and pushing to make it go down is one of the first most basic things taught in flight school.

Keep in mind we are talking about approach-to-stall (stickshaker) procedure, not fully-developed stall recovery, so there will be no pitch effect involved. But, the pull-up instinct is definitely ingrained in us when facing the prospect of falling out of the sky. Gabriel (and a few other pilots) have proven that this can be overcome with knowledge and discipline, so that's what we need to be doing.

[elaw]

...until...

The old procedures were written with the assumption that stalls would be occurring in close ground proximity, so altitude loss was prioritized. Now we know better.

Well we think we know better!

Although a number of the Accidents Du Jour have occurred at high altitudes, the reality is that aircraft can, have, and will stall tens, hundreds, or thousands of feet above the ground. The best answer may be to train pilots on the similarities and differences between stalls at low and high altitude and the differences and similarities in how to deal with them.

Those procedures, the ones I've seen, do not call for pitch increases; they only call for maintaining pitch (or 'managing' pitch around the current setting), but do rely on power to recover.

That, taken by itself, is really scary.

In pretty much all modern not-automated-to-death aircraft (sorry Airbus), the nose will drop when the plane begins to stall (sometimes one wing, sometimes both, but either way the nose drops). If pilots are being trained to hold attitude when that happens, they will pull back on the stick/yoke. Because when the nose is dropping, how else do you raise it? Pulling on the controls to make the nose go up and pushing to make it go down is one of the first most basic things taught in flight school.

What I learned in my (very limited compared to some here) flight training was when the plane begins to stall, you first add power... usually a lot of it. Second, but really at pretty much the same time, you relax back pressure on the yoke (or push forward more if you were already pushing) just enough to make the wings "hook up" again with the airflow. It's a bit like breaking an understeering car out of a skid... you need to get the front wheels aligned to the direction the car is actually going, and not where they're unsuccessfully trying to make it go. But I suppose that might require natural control feel that's not present in an airliner?

[Evan]

That being said, the recommended stall warning recovery procedure for several years and several specific commercial aircraft was to power up and aim for a specific, near-maximum climb attitude...

...and I think it was a reasonably effective procedure for most stall warnings with a generally excellent limitation of altitude loss.

...until...

The old procedures were written with the assumption that stalls would be occurring in close ground proximity, so altitude loss was prioritized. Now we know better. Those procedures, the ones I've seen, do not call for pitch increases; they only call for maintaining pitch (or 'managing' pitch around the current setting), but do rely on power to recover. They were misunderstood (and misinstructed), I think, to instill an upward-pulling instinct. They were also not taking into consideration that pilots would get themselves into an extended idle situation by entirely ignoring the airspeed and trying to salvage unstable (high and fast) approaches, so the pitch coupling and spool-up factors were under-considered. Pitch coupling is most pronounced on powerful, underslung engines at low speeds and spool-up is slowest after engines have settled at flight idle. But, live and learn, they came to realize that the SAFEST general procedure was to prioritize a reduction in pitch (not a push over) unless in close ground or obstacle proximity.

Again, human factors were now considered rather than strict aerodynamics. We want pilots to have an 'ease off the column' instinct or even a 'push forward' instinct rather than a 'pull back' instinct. I don't think we have to worry about pilots developing a 'dive into the ground' instinct...

[3WE]

It will increase, thus the AoA will decrease. But possibly not soon enough to prevent the flight path vector from first dramatically decreasing into a smoking hole...

That being said, the recommended stall warning recovery procedure for several years and several specific commercial aircraft was to power up and aim for a specific, near-maximum climb attitude...

...and I think it was a reasonably effective procedure for most stall warnings with a generally excellent limitation of altitude loss.

[Evan]

What will happen to the flight path vector if you keep pitch the same and increase speed?

It will increase, thus the AoA will decrease. But possibly not soon enough to prevent the flight path vector from first dramatically decreasing into a smoking hole...

[3WE]

And let us not forget what happens if you wind up in Coffin Corner...

If you speed up, you break up and die.
If you slow down, you break up and die.

The ONLY way out of coffin corner is to maintain perfect airspeed, burn off some significant fuel and then slowly descend.

(Yes, I am being both sarcastic and factual at the same time...context matters)

[3WE]

***the flight path angle (flight path vector) and the pitch. Speed doesn't directly affect AoA,***

What will happen to the flight path vector if you keep pitch the same and increase speed?

[3WE]

That... isn't necessarily true. You can maintain the exact same attitude and increase speed, and AoA will decrease. Just like the opposite condition which has caused so many problems for aircraft on approaches... maintain the same pitch attitude but decrease speed, and AoA increases... until the plane stalls and slams into the seawall at the end of the runway.

Thank you.

As the saying goes: Indeed.

Edit: Upon further thought, in the case you reference, I think Hui Theiu Lo may very likely have been giving increasing nose-up inputs to maintain a proper glide path, until the pull up got a little too relentless...and that is at least part of the equation here.

[Evan]

That... isn't necessarily true. You can maintain the exact same attitude and increase speed, and AoA will decrease. Just like the opposite condition which has caused so many problems for aircraft on approaches... maintain the same pitch attitude but decrease speed, and AoA increases... until the plane stalls and slams into the seawall at the end of the runway.

Angle-of-attack is the difference in angle between the flight path angle (flight path vector) and the pitch. Speed doesn't directly affect AoA, but in order to maintain level flight at a lower airspeed, the AoA must be increased to generate more lift (by increasing the pitch). Stall occurs when the increase in pitch raises the AoA above critical angle. If you fly too slow and don't increase pitch to maintain altitude, you will only sink. Increasing speed in level flight allows you to generate the same lift at a lower AoA, using a lower pitch angle.

At least that's what Boeing says. Gabriel might have something to say about that.

[Evan]

See? I told you didn't. You (Evan) can't disconnect the concepts of lowering the nose from reducing AoA.

Ok, yes, I'm back to confused. As I understand from all my Gabrielian and non-Gabriellian reading on the subject that, while AoA is certainly not a direct function of pitch, lowering the AoA in wings-level stall avoidance is initially an exercise in pitch. I understand that in your situation, the only thing you could do (and the right thing to do in any case) was lower the pitch ever-so-slightly, both to accelerate and to back off from critical angle. Once that was done, you could hold that pitch and even climb (as you did) as the airspeed comes up, lift is increased and the flight path angle is increased, thus lowering the AoA. And so you must initially give up some altitude (or climb gradient) while minimizing that loss by finding the greatest available lift below (at?) stickshaker. You used column inputs (also known as pitch inputs) to oscillate around the stickshaker AoA until the speed allowed you to safely climb at a lower AoA.

So how am I wrong about that?

EDITED: because I saw the error of my ways.

[elaw]

[SIZE=4]I some sense, Evan is right...you are going to change attitude if you are going to change AOA. They are basically directly linked...if you want to change one, you will almost always need to adjust the other.

That... isn't necessarily true. You can maintain the exact same attitude and increase speed, and AoA will decrease. Just like the opposite condition which has caused so many problems for aircraft on approaches... maintain the same pitch attitude but decrease speed, and AoA increases... until the plane stalls and slams into the seawall at the end of the runway.