A320 stall recovery
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A320 stall recovery
Hi A320 guys
Clean stall recovery at say 10000ft. Airbus says must use slats. It also says slat is not a part of stall recovery but flight path recovery. So normally after stall warning has stopped some thrust then extend slat and as speed come out of VLS start pitching up. But some pilots either get secondary stall warning or alternatively get VFE warning. I have seen some using the bird. Anybody has any technique that makes it easier or how does Airbus themselves teach this?
Clean stall recovery at say 10000ft. Airbus says must use slats. It also says slat is not a part of stall recovery but flight path recovery. So normally after stall warning has stopped some thrust then extend slat and as speed come out of VLS start pitching up. But some pilots either get secondary stall warning or alternatively get VFE warning. I have seen some using the bird. Anybody has any technique that makes it easier or how does Airbus themselves teach this?
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I applied the same basic technique that I used in a cessna. Reduce the AoA. This is the first and last priority. Once above Vls, start raising the nose- slowly if the margin to Vls is slim.
If you get a secondary stall, you're being too aggressive. If you get a Vfe warning, who cares? That's going to be the least of the paperwork you'll have to do. But to put on my instructor hat, I'd say you need to be more aggressive with the pitch up.
As an aside, a more interesting scenario is low altitude (below 1,000ft) stall recovery
If you get a secondary stall, you're being too aggressive. If you get a Vfe warning, who cares? That's going to be the least of the paperwork you'll have to do. But to put on my instructor hat, I'd say you need to be more aggressive with the pitch up.
As an aside, a more interesting scenario is low altitude (below 1,000ft) stall recovery
Last edited by Check Airman; 31st Mar 2021 at 06:02.
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Using the bird is not recommended for dynamic manoeuvers. A friend of mine who’s TRE told me that during a stall recovery exercice, a pilot failed to recover from a stall and crashed cause he confused the bird with the pitch...
From my experience the guys who entered a secondary stall is because they start pitching up too early or too aggressively or both.
From my experience the guys who entered a secondary stall is because they start pitching up too early or too aggressively or both.
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I noticed that pilots who struggle have two issues they are too fast in pitch up causing secondary stall warning and then hanging around three to five degrees of pitch getting VFE exceedance. When I have talked them through the manoeuvre they do it without a problem. So basically inadequate scan. Actually landing configuration gear down direct law stall is easier as you rarely get secondary stall warning why is that? And high level stall like FL 350 stall warning sounds when well inside the amber Barber pole. In alternate law there's VLS and below that is Vsw. Isn't it supposed to be the top of Vsw scale?
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Are they already flying with the bird displayed or do they, at some point during the maneuver, bring the bird up? Our manual specifically states do not use FD commands during recovery, and I can’t imagine a pilot, during a stall or recovery reaching up to select the bird.
Upset (stall) recovery for us is “Recognize, announce, PUSH, ROLL, THRUST, STABILIZE.” (The only time we put flaps1 out is on takeoff if they were inadvertently selected up.)
Vilas I don’t know what your outfits standard is but IMHO, but if they get one split second secondary stall, recognize it, get out of it and stay out of it, after the debrief I would call that a win. Recognition is key.
Upset (stall) recovery for us is “Recognize, announce, PUSH, ROLL, THRUST, STABILIZE.” (The only time we put flaps1 out is on takeoff if they were inadvertently selected up.)
Vilas I don’t know what your outfits standard is but IMHO, but if they get one split second secondary stall, recognize it, get out of it and stay out of it, after the debrief I would call that a win. Recognition is key.
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Capt Mongo
In agreement. In alternate law you may be flying with bird or in some cases with FD. If stalled one should be able to recover from both. One wouldn't be asking for bird or switching off FD. Secondary stall warning is not necessarily a stall but a precursor slight unloading rectifies that and then continue again. Dynamic phase bird is unreliable also true. Just trying to gather views and training methods on the subjects. What is noticed in avoiding Vfe exceedance in lower level FL100 clean stall is not having too much thrust. Also what's the criteria to assess satisfactory grade?
In agreement. In alternate law you may be flying with bird or in some cases with FD. If stalled one should be able to recover from both. One wouldn't be asking for bird or switching off FD. Secondary stall warning is not necessarily a stall but a precursor slight unloading rectifies that and then continue again. Dynamic phase bird is unreliable also true. Just trying to gather views and training methods on the subjects. What is noticed in avoiding Vfe exceedance in lower level FL100 clean stall is not having too much thrust. Also what's the criteria to assess satisfactory grade?
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A320 stall warning is not compensated for compressibility (unlike A330/350) I.e. it comes late at high altitude, well below Vsw. You’ll also have deterrent buffet well before that.
Food for thought:
Wrt to your point of pilots entering secondary stall during recovery: a point often missed is the flying characteristic in alternate law. A release of forward stick pressure to neutral is in fact commanding a return to 1G (increase in loadfactor), which may lead to an accelerated secondary stall after initial recovery.
Food for thought:
Wrt to your point of pilots entering secondary stall during recovery: a point often missed is the flying characteristic in alternate law. A release of forward stick pressure to neutral is in fact commanding a return to 1G (increase in loadfactor), which may lead to an accelerated secondary stall after initial recovery.
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Thanks for the first part but about secondary stall it doesn't happen with release of stick but somewhere during the pull out when the stick is back of neutral. Offcourse release stops the warning.
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During my initial type rating on the A320 we did quite a few stall recovery demonstrations, in fact a whole simulator session just on that. One of the things we did was get into a stall below 20.000ft, not follow the memory and just put flaps to one. The result was being out of stall. I questioned the simulator fidelity of that, and of course we have been trained to follow the memory items at all times which mentions flaps 1 very late in the flight path recovers. But it was startling to see how much of an effect supposedly the slats have. I always wonder if that simulator behavior was indeed correct or not.
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Denti
After the stall recovery philosophy changed all sims now have the updated data package with better fidelity as older ones were not representative of Aircraft behaviour.
After the stall recovery philosophy changed all sims now have the updated data package with better fidelity as older ones were not representative of Aircraft behaviour.
I'm not the Ace of Base, but I manage, Just
I noticed that pilots who struggle have two issues they are too fast in pitch up causing secondary stall warning and then hanging around three to five degrees of pitch getting VFE exceedance. When I have talked them through the manoeuvre they do it without a problem. So basically inadequate scan. Actually landing configuration gear down direct law stall is easier as you rarely get secondary stall warning why is that? And high level stall like FL 350 stall warning sounds when well inside the amber Barber pole. In alternate law there's VLS and below that is Vsw. Isn't it supposed to be the top of Vsw scale?
Being as you can only "Stall" an Airbus when not in Normal Law, and the actual amount of time I have spent flying in ALT/Direct Law is limited, ie SIM's or the very rare inflight Failure, I am not really "Current" with the subtle control differences.
IE: No Thrust compensation.
So, I do the initial actions well,
Pitch down, Wings Level,
-when out of stall-
This next step is the were I have come unstuck (and many others obviously)
THRUST increase (there is no mention of PITCH change)
In NORMAL LAW, when thrust is increased, the Airbus magic holds the pitch to compensate.
In ALT/DIRECT Law, this is not the case, so any thrust increase will lead to an increase in PITCH.
Generally, at this point, I am hauling back on the stick trying not to lose too much Altitude or Overspeed, add in a large increase of THRUST, and bingo, massive Pitch up and Secondary Stall.
SO, I now get a chance to show the Check Capt that I can learn from my mistakes, and during my Self Induced Repeat, I go through this process again, but this time, I don't haul back on the stick, but allow the thrust to do its thing and raise the nose for me. (It may need a little help).
Then I dutifully go through the follow up actions, and hope that is good enough to not actually have to do it again. (I generally have to, and usually do ok on the second go. Fast learner, eh? ;-))
What do really I learn?
Well, the above of course, but also, my scan rate was appallingly slow. We get so used to the "Normal" Airbus magic, that anything out of "Normal" needs to be carefully thought through and you must really "FLY" the aeroplane, which obviously hasn't happened because you have managed to Stall it in the first place.
As for using the "BIRD" for recovery, unless it was already on, I wouldn't waste the time asking for it, just do the recovery steps as prescribed.
Flaps 1?
It says to do it, so you should, but at this point be very slow and deliberate, check the IAS, check the ALT, call "Flap 1". With all that adrenaline coursing through your veins, the last thing you need is another Master Warning going off.
That's some of the dumb things I've done in the SIM, I've got plenty more
Last edited by Roj approved; 1st Apr 2021 at 05:23. Reason: spelling
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In ALT/DIERCT Law, this is not the case, so any thrust increase will lead to an increase in PITCH.
I have practiced this a few times in the sim to look more closely at what goes on.
As you slowly approach VLS the THS is trimming nose up to maintain attitude. As you reduce speed THS freezes and then you have to apply more and more back pressure on the sidestick to maintain attitude - low speed protection.
At the moment of first stall warning you are significantly out of trim - requiring significant back pressure to achieve a stall warning.
In the recovery you pitch forward but in reality all you do is release back pressure and the AoA reduces/speed starts to increase rapidly. This is all quite rapid and you accelerate past the airspeed at which the trim froze at rapidly. The THS takes time to unwind the ANU position and as you continue to accelerate you end up significantly out of trim requiring in fact forward pressure to reduce the pitch change. Selecting Flaps 1 adds to the lift and to the out of trim situation.
I have done this a few times in an ultra modern L3 A320 simulator and taking your hands off the controls at the first stall warning AND selecting Flaps 1 BUT maintaining idle thrust results in a secondary stall/stall warning occur as the aircraft pitches up aggressively. Hands off!!! Adding thrust only exacerbates this issue obviously due to acceleration and pitch/power couple - recall that during those crucial seconds the THS is significantly out of trim and it takes time to recover the trim.
I reckon having had several goes at trying to make this maneuver more predictable and smooth and avoid the secondary stall consistently the solution is to in fact manually trim nose down a few tenths of a unit as soon as you begin pitching up and calling for Flap 1. I tried this several times and the recover can be flown much more smoothly this way.
I expect to get harangued from many over the idea of daring to deviate from Airbus/training techniques but to be clear; all I'm suggesting is trimming an out of trim aircraft AFTER a stall warning which is not an actual stall.
I flew the 737 for years and anyone who's flown an aircraft like that knows that occasionally you trim in a counterintuitive manner to flying the aircraft safely - dual engine go-around you would have to apply forward pressure to the control column to avoid over pitching as the power came on and until you had trimmed a chunk nose down to compensate for the thrust.
As you slowly approach VLS the THS is trimming nose up to maintain attitude. As you reduce speed THS freezes and then you have to apply more and more back pressure on the sidestick to maintain attitude - low speed protection.
At the moment of first stall warning you are significantly out of trim - requiring significant back pressure to achieve a stall warning.
In the recovery you pitch forward but in reality all you do is release back pressure and the AoA reduces/speed starts to increase rapidly. This is all quite rapid and you accelerate past the airspeed at which the trim froze at rapidly. The THS takes time to unwind the ANU position and as you continue to accelerate you end up significantly out of trim requiring in fact forward pressure to reduce the pitch change. Selecting Flaps 1 adds to the lift and to the out of trim situation.
I have done this a few times in an ultra modern L3 A320 simulator and taking your hands off the controls at the first stall warning AND selecting Flaps 1 BUT maintaining idle thrust results in a secondary stall/stall warning occur as the aircraft pitches up aggressively. Hands off!!! Adding thrust only exacerbates this issue obviously due to acceleration and pitch/power couple - recall that during those crucial seconds the THS is significantly out of trim and it takes time to recover the trim.
I reckon having had several goes at trying to make this maneuver more predictable and smooth and avoid the secondary stall consistently the solution is to in fact manually trim nose down a few tenths of a unit as soon as you begin pitching up and calling for Flap 1. I tried this several times and the recover can be flown much more smoothly this way.
I expect to get harangued from many over the idea of daring to deviate from Airbus/training techniques but to be clear; all I'm suggesting is trimming an out of trim aircraft AFTER a stall warning which is not an actual stall.
I flew the 737 for years and anyone who's flown an aircraft like that knows that occasionally you trim in a counterintuitive manner to flying the aircraft safely - dual engine go-around you would have to apply forward pressure to the control column to avoid over pitching as the power came on and until you had trimmed a chunk nose down to compensate for the thrust.
Strictly this is only applicable to direct law because alternate in pitch is same as normal law. However since the speed is below VLS the ability to hold the flight path may be not that great. At two places need to hold down with thrust increase and while slat are extending. After that when speed is out of VLS a gentle but continuous pitch up till established in climb and trend arrow in control enables you perform the manoeuvre without a hiccup.
BoeingDriver99, re: THS position, that makes sense why it has a pitch up tendency as the IAS increases with the thrust increase.
I’m still learning👍
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The deployment of slats will allow a shallower flight path recovery (thus help avoiding impact with terrain at low levels) which is far more important than exceeding the slats speed by a few knots.
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