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Old 2nd Jun 2011, 17:46
  #1327 (permalink)  
Lonewolf_50
 
Join Date: Aug 2009
Location: Texas
Age: 64
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BOAC, I read that article again, and it seems to be contradictory.

{AF 447} After stalling, the A330's angle of attack stayed above 35°. But while this exceeded the threshold for the abnormal attitude law, the flight control computers had already rejected all three air data reference units and all air data parameters owing to discrepancy in the airspeed measurements.

{My thought: does this mean that AoA greater than 30 deg does not trigger Abnormal Law, or that there are some more tie ins to the comparisons {summed inputs into the flight computer} requiring (valid?) airspeed input before that law is selected?}

Abnormal law could only have been triggered by an inertial upset, such as a 50° pitch-up or bank angle of more than 125°. "That never occurred," says French accident investigation agency Bureau d'Enquetes et d'Analyses.

The BEA is still attempting to explain why AF447's crew failed to rescue the aircraft after it climbed to 38,000ft and stalled. The pilot's control inputs were primarily nose-up, despite the stall condition.

There has been no indication that the aircraft switched into any other control law, other than alternate, during the accident - suggesting that auto-trim was available throughout the descent.

{skip a bit}

In its conclusions over the {Perpignan} accident the BEA highlighted the rarity of the need to trim manually, which created a "habit" of having auto-trim available made it "difficult to return to flying with manual trimming".

"One of the only circumstances in which a pilot can be confronted with the manual utilisation of the trim wheel is during simulator training," it said. "However, in this case, the exercises generally start in stabilised situations."

In the wake of the A320 accident, near Perpignan in November 2008, the BEA recommended that safety regulators and manufacturers work to improve training and techniques for approach-to-stall situations, to ensure control of an aircraft in the pitch axis.
That doesn't answer the mail for dealing with a stalled aircraft. From from a common sense perspective, in terms of operations, "do better at NOT stalling" it certainly makes sense as a training objective.
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