Why did they want us to maintain altitude
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Why did they want us to maintain altitude
As I go through the Airbus Upset Recovery Training they mention about how we used to try to maintain altitude in a stall recovery in the sim until the obvious became obvious and it was not longer trained that way.
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
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As I go through the Airbus Upset Recovery Training they mention about how we used to try to maintain altitude in a stall recovery in the sim until the obvious became obvious and it was not longer trained that way.
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
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As I go through the Airbus Upset Recovery Training they mention about how we used to try to maintain altitude in a stall recovery in the sim until the obvious became obvious and it was not longer trained that way.
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
AFAIK this technique was rescinded after or at least around the Air France accident, probably with the background that there are circumstances where it will not work, i.e. if you're so far behind the power curve that the aircraft will not accelerate without dropping the nose, and given that a stalled wing can only be recovered by lowering angle of attack.
I'd still be reluctant to push forward heartily if I e.g. botched a turn during a circling approach/visual pattern and got a rattle of the stick shaker, where a dab of power will accelerate the A/C sufficiently to avoid harm. The current theory says "push down" regardless of circumstances, but I haven't so far got a reply whether that's really a good idea in the "very low" scenario.
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AFAIK this technique was rescinded after or at least around the Air France accident
Last edited by vilas; 6th Aug 2018 at 17:10.
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The A330 manual at our company does have a stall recovery after take off memory procedure vs. the regular stall recovery procedure.
The procedure calls for TOGA and to set pitch to 15 degrees. At low altitudes the ability to simply power ones way out of a stall is much greater than at altitude.
My company now insists on all pilots performing at least one stall recovery every six months. It alternates between low and high altitude. In my experience if the recovery is done at a standard pace while taking care of the secondary stalls, at low altitudes 700 feet is about what one can expect to loose.
The secondary stalls is also far more common on the narrow bodies.
The procedure calls for TOGA and to set pitch to 15 degrees. At low altitudes the ability to simply power ones way out of a stall is much greater than at altitude.
My company now insists on all pilots performing at least one stall recovery every six months. It alternates between low and high altitude. In my experience if the recovery is done at a standard pace while taking care of the secondary stalls, at low altitudes 700 feet is about what one can expect to loose.
The secondary stalls is also far more common on the narrow bodies.
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At low altitudes the ability to simply power ones way out of a stall is much greater than at altitude.
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If you ever get to the point of stalling an airliner, then the emphasis has to be on unloading the wing so you’re flying again and under some sort of control. Everything else goes out of the window. Get as close to the ground as you like during the recovery as long as you don’t hit it: if you have speed (== life) you can pull out - if you’re still at the far end of the drag curve you might not be able to.
I take the view that if you manage to unwittingly aerodynamically stall a jet transport aircraft, especially at low level, then you’re probably going to screw up the recovery as well...
I take the view that if you manage to unwittingly aerodynamically stall a jet transport aircraft, especially at low level, then you’re probably going to screw up the recovery as well...
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This is true, but in the end the reduction in AOA is accomplished by the stick being pushed forward, as it always is; and this must not be forgotten. (Especially in planes with underwing engines and a nose-up thrust couple.) The phrase "powering out of the stall" needs to die in a fire, starting yesterday, because people are always going to misinterpret it in the most simplistic way possible. Say "only reduce the AOA a little bit" instead.
Ryanair Eindhoven incident
They went from chasing the glide idle thrust fully configured to 20° nose up and sped dropping through the floor in half a second. The copilot recovered the aircraft beautifully. It does happen...
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The A330 manual at our company does have a stall recovery after take off memory procedure vs. the regular stall recovery procedure.
The procedure calls for TOGA and to set pitch to 15 degrees. At low altitudes the ability to simply power ones way out of a stall is much greater than at altutude.
The procedure calls for TOGA and to set pitch to 15 degrees. At low altitudes the ability to simply power ones way out of a stall is much greater than at altutude.
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Can't speak for Airbus but we used to differentiate between "stall without risk of imminent ground contact" and "stall well clear of ground" on several types I flew. "Without risk of imminent ground contact" it was like the current "shove stick forward, accelerate, gently pull" while "with risk of imminent ground contact" you'd apply maximum thrust and try to lose as little altitude as possible while accelerating.
AFAIK this technique was rescinded after or at least around the Air France accident, probably with the background that there are circumstances where it will not work, i.e. if you're so far behind the power curve that the aircraft will not accelerate without dropping the nose, and given that a stalled wing can only be recovered by lowering angle of attack.
I'd still be reluctant to push forward heartily if I e.g. botched a turn during a circling approach/visual pattern and got a rattle of the stick shaker, where a dab of power will accelerate the A/C sufficiently to avoid harm. The current theory says "push down" regardless of circumstances, but I haven't so far got a reply whether that's really a good idea in the "very low" scenario.
AFAIK this technique was rescinded after or at least around the Air France accident, probably with the background that there are circumstances where it will not work, i.e. if you're so far behind the power curve that the aircraft will not accelerate without dropping the nose, and given that a stalled wing can only be recovered by lowering angle of attack.
I'd still be reluctant to push forward heartily if I e.g. botched a turn during a circling approach/visual pattern and got a rattle of the stick shaker, where a dab of power will accelerate the A/C sufficiently to avoid harm. The current theory says "push down" regardless of circumstances, but I haven't so far got a reply whether that's really a good idea in the "very low" scenario.
Take a look at the RYR incident in Eindhoven:
The new group of aviators will have only ever learned nose down and power idle until fully recovered then smoothly add power, and that is likely to also cause a crash someday too
If you’re getting stick shaker at 500’, then either conditions are such that an approach is not prudent or you haven’t been paying attention to flying basics, in which case I refer to my earlier comment about recoveries. The stick shaker doesn’t change its tune whether you are 1kt or 15kts into its warning envelope, so you’re experiencing a time-critical event and need to do the right thing right now!
As I go through the Airbus Upset Recovery Training they mention about how we used to try to maintain altitude in a stall recovery in the sim until the obvious became obvious and it was not longer trained that way.
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
But one does have to ask, how did it become that way in the first place. Was there a desire by the Powers That Be to not have an ATC violation or was it assumed that a stall could only ever happen close to the ground.
Was this something that came from the manufacturers or the regulators?
Perhaps it is all lost in the sands of time but it would be interesting to know how it was done back in the '60's or earlier.
Anyone?
This requirement was fed back into the type-rating training courses and this eventually became the ‘standard method’ of teaching stall recovery. It was certainly the way I was taught to recover in the 737 and 747. I thought it was wrong at the time (unless at very low altitude) but discussing it with the examiner did not prove worthwhile.
I was pleased when both Boeing and Airbus revised their techniques following the Colgan, Air France and Turkish crashes. I was taught the ‘stick forward first’ method on the A320 and 787.
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The stalls done in the Sim are well past the incipient stage.
I do think they are making a mistake trying to sell everyone a "one size fits all" recovery
At zero body angle the speed increases slowly until at 230 knots IAS we gently level out. This results in about 3000 feet loss of height. The 230 knots IAS figure comes from the FCTM where it says if FMC speeds not available above 25,000 ft use Vref40 +100 knots for holding. That is roughly 230 knots IAS.
If the stall was due to mishandling in severe turbulence and during the recovery severe turbulence still exists, then the aircraft is held in the descent angle until severe turbulence speed in attained and then recovered to level flight. Expect a height loss of 5000 ft. In each case no attempt is made to revert to level flight until those safe airspeeds are attained.
For low altitude practice stall on final approach, the autopilot is coupled to the ILS and at 1500 ft agl both thrust levers set to idle. The AP trims the stabiliser more or less continually backwards as the AP tries to fly the glide slope and the IAS reduces until around Vref minus 25 knots the stick shaker goes off. There is no discernible buffet. By the time the airspeed reaches Vref minus 25 and the stick shaker operates (and you wonder how crews has missed the speed indications in previous accidents/incidents) , the stabiliser trim would have moved back to about 13 units under the AP as it tries to hold the ILS glide slope angle.
Max (firewall) power is applied, the AP is disengaged and nose lowered to around five degrees nose up. Anything lower than that will result in severe height loss which could be dangerous if close to the ground. It then becomes a compromise between descending while close to the ground and picking up speed and trying to "claw" your way up at low speed. At the same time the pitch up caused by full power is contained by strong forward control column while simultaneously applying immediate continuous forward stabiliser trim for about seven seconds to place the trim in a position where the forward elevator pressure becomes effective. While still maintaining five degrees nose up, the IAS gradually increases, although some height loss occurs but only for a few seconds.
By now, about 3-500 feet has been lost during the recovery and as soon as airspeed passes through Vref in the ensuing climb, the aircraft is pitched up to normal GA attitude and Flaps 15 selected. Flap is left at landing flap until Vref is reached on the recovery. That is because if flap is selected to 15 as part of the recovery while airspeed is well below Vref then the aircraft is in danger of stalling.
I am sure there are other ways "to skin the cat" as the saying goes, but these two methods work well in the simulator.
Constructive criticism welcomed but please don't shoot the messenger on this one
Last edited by Judd; 7th Aug 2018 at 16:01.
Constructive criticism welcomed but please don't shoot the messenger on this one
The stabiliser is effectively the most powerful flying control on the 737 (and other types) and the elevator is the trim. Moving the stabiliser for long periods in one direction can be the best way out of a bad situation or if done wrong, seal your fate. Scary stuff in a situation where SA has by definition been severely degraded or lost altogether...
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Also, why in the current aircraft I'm training on (C172) if i pull nose up to say 20 degrees pitch at 100 kts on idle power, I don't stall (at least not for a short while). However, if I pull nose up at 50 kts with full flaps, stall will be imminent, without even being able to reach 20 degrees pitch up.
I am not disagreeing with what you say, just interested in the answer. In ground school we learned about the critical angle and that a stall can happen at any speed etc etc, but then we learn about Vs, Vs1 etc and see our susceptibility to stall is determined according to these speeds, even with 0 degrees pitch you'll stall at not much beneath them.
So why is there such a huge emphasis on 'stall speeds' in training?
Also, why in the current aircraft I'm training on (C172) if i pull nose up to say 20 degrees pitch at 100 kts on idle power, I don't stall (at least not for a short while). However, if I pull nose up at 50 kts with full flaps, stall will be imminent, without even being able to reach 20 degrees pitch up.
I am not disagreeing with what you say, just interested in the answer. In ground school we learned about the critical angle and that a stall can happen at any speed etc etc, but then we learn about Vs, Vs1 etc and see our susceptibility to stall is determined according to these speeds, even with 0 degrees pitch you'll stall at not much beneath them.
Also, why in the current aircraft I'm training on (C172) if i pull nose up to say 20 degrees pitch at 100 kts on idle power, I don't stall (at least not for a short while). However, if I pull nose up at 50 kts with full flaps, stall will be imminent, without even being able to reach 20 degrees pitch up.
I am not disagreeing with what you say, just interested in the answer. In ground school we learned about the critical angle and that a stall can happen at any speed etc etc, but then we learn about Vs, Vs1 etc and see our susceptibility to stall is determined according to these speeds, even with 0 degrees pitch you'll stall at not much beneath them.
Maintaining altitude was never my concern but containing the stall to a smaller block with power or thrust is what one is trying to accomplish...lower the AOA while setting max thrust is how I've always seen.
Edit: Yes I'm aware of the thrust possibly causing nose up in the recovery but pilots are supposed fight that if expected
Just to add the the maximum weight to ever be carried by the wing is the weight that the wing carries at stall
Edit: Yes I'm aware of the thrust possibly causing nose up in the recovery but pilots are supposed fight that if expected
Just to add the the maximum weight to ever be carried by the wing is the weight that the wing carries at stall
Last edited by Pugilistic Animus; 8th Aug 2018 at 00:12.