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Old 30th May 2011, 16:10
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FlexibleResponse
 
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New Airbus STALL RECOVERY procedure
No comments on the FOT Airbus issued this past week advising of a revised STALL RECOVERY procedure.?
FIREWALLing the throttles first has been the drill since primary training but now Airbus are saying to wait until the pitch has been lowered as it might even be necessary to reduce thrust to regain pitch authority. This seems to be quite a change to just throw out there with no forewarning or am I reading too much into it.

For the A320 fleet:

As soon as any stall indication (could be aural warning, buffet...) is recognized, apply the immediate actions :
- NOSE DOWN PITCH CONTROL . . . . . . . . . . . . . . . . . . . . APPLY
This will reduce angle of attack
Note: In case of lack of pitch down authority, reducing thrust may be necessary
- BANK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WINGS LEVEL

• When out of stall (no longer stall indications) :
- THRUST . . . . . . . . . . . INCREASE SMOOTHLY AS NEEDED
Note: In case of one engine inoperative, progressively compensate the thrust asymmetry with rudder
- SPEEDBRAKES . . . . . . . . . . . . . . . . . . . CHECK RETRACTED
- FLIGHT PATH . . . . . . . . . . . . . . . . . . . RECOVER SMOOTHLY
• If in clean configuration and below 20 000 feet :
- FLAP 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SELECT
Note: If a risk of ground contact exists, once clearly out of stall (no longer stall indications), establish smoothly a positive climb gradient.
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And sadly once again there is NO mention that the ALL-FLYING HORIZONTAL STABILIZER (Airbus call it the THS) might need to be MANUALLY repositioned nose down to regain control of the aircraft in a high alpha situation!

Gentlemen, what the hell is wrong with us? The evidence that we have been given so far by BEA is startlingly clear...why can't we see it for what it is?

I will try to keep this simple.

1. Airbus designed the computer aided flight controls when operating in "normal law" to PREVENT the aircraft from stalling.

2. To achieve pitch control in normal law, the pilots fore and aft sidestick commands are interpreted as incremental (+/-) g commands...until a certain alpha is reached.

3. When that certain alpha (close to the stall) is reached the flight control law becomes an alpha command law so that fore and aft sidestick commands become incremental (+/-) alpha commands...but the flight controls still prevents the aircraft from stalling.

4. IF the aircraft reaches a FLIGHT CONDITION that is outside of the NORMAL LAW flight envelope, the flight controls decide that they must have made some sort of mistake. Therefore in that situation they revert to RECOVERY LAW so that the pilots have full and direct command of the flight control surfaces to be able to recover the aircraft back inside the approved flight envelope (ie, the movement of the sidestick moves the ELEVATORS and AILERONS/SPOILERS directly without refinements).

5. Unfortunately, WHEN the flight controls revert to RECOVERY LAW, the THS FREEZES in the current position.

6. A RED ECAM WARNING tells the pilots "USE MAN PITCH TRIM ONLY".

7. However, with the extreme situation of the aircraft out of control and probable associated and conflicting RED WARNINGS of STALL and/or OVERSPEED with associated AURAL WARNINGS announcing same, it is all too easy for pilots to become overloaded.

8. It is extremely easy for pilots to OVERLOOK the requirement to MANUALLY adjust the THS so that the pilot has ADEQUATE pitch authority to regain control. I have seen that so many times when training pilots in the sim, it makes my head spin.

9. Now in the case of of AF447, BEA has told us that the THS froze at 13 degrees aircraft nose up...and that it stayed at 13 degrees aircraft nose up from 38,000 feet until impact with the sea. It would appear that there was no MANUAL input to the THS throughout the loss of control event.

10. This would indicate that none of the pilots realized that they were trying to control the pitch attitude of the aircraft with the TINY ELEVATOR on the back of the HORIZONTAL STABILIZER which in itself was almost maximum fully trimmed aircraft nose up.

11. They were trying to fly the aircraft with EXTREMELY LIMITED pitch authority.

Yeah I have some thousands of hours flying the A330 and A340 series of this aircraft including training and checking airline pilots and some thousands of hours doing likewise on the A300 and A340 simulators doing same including Jet Upset Training...but what would I know?
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