PPRuNe Forums - View Single Post - AF 447 Search to resume
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Old 18th Dec 2010, 21:41
  #2603 (permalink)  
Machinbird
 
Join Date: Jul 2009
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If the search is only North of LKP is indeed true, then they are absolutely discounting the possibility of AF447 losing control in Normal Law either at or slightly before the ACARS sequence.
From the BEA Perpignan accident report:
When the stall warning sounded, the Captain reacted by placing the thrust levers in the TO/GA detent and by pitching the aeroplane down, in accordance with procedures. The nose-down input was not however sufficient for the automatic compensation system to vary the position of the horizontal stabilizer, which had been progressively deflected to the pitch-up stop by this system during the deceleration. The Captain controlled a left roll movement, caused by the stall. The aeroplane’s high angle of attack and the roll movements generated asymmetry, and a speed variation between ADR 1 and 2 appeared. This increasing divergence caused a rejection of the three ADRs by the FAC then the ELAC. The flight control system then passed into direct law. It is likely that the crew did not notice this due to the emergency situation and the aural stall warning that covered the warning of a change of flight control laws.
The point of the above is to show that a AF447 departure from controlled flight in Normal Law would be expected to cause the ADRs to reject and the control laws to degrade.
If no recovery, the aircraft would be found close to LKP, even possibly South of LKP.
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