View Full Version : ALASKAN 261 - A THEORY?
unusualAttitude
28th Oct 2000, 09:16
I have recently listened to the ATC tape of the AS 261 drama and tragedy off the Californian coast. We now know that a tailplane mechanical fault is regarded by the investigation thus far as having caused an uncontrollable pitch-down. Observers reported to ATC that--eventually--the a/c was inverted and impacted the water in this attitude.
What was there about this control problem by which the a/c would become inverted? And I wonder...
Is it beyond the realms of possibility that the crew might have deliberately rolled the aeroplane over in a desperate attempt to get the nose 'up'?
Given their predicament, might such action have succeeded?
Would YOU do it?
Petergozinya
28th Oct 2000, 17:14
Anything to stay in the air............
Yes I would have tried.
PPRuNe Radar
30th Oct 2000, 23:11
Once the catastrophic failure occured I am not sure that the crew had any chance to control the aircraft.
As I understand it, the thread on the screwjack which is used to move the horizontal stabiliser was OK but the thread on the horizontal stabiliser gimbal nut assembly itself was excessively worn (stripped) allowing uncontrolled travel. Aerodynamic forces then caused the 'stops' on the system to be sheared allowing full and uncontrolled travel of the horizontal stab outside the normal limits. My money would then be on the aircraft itself ending up inverted rather than due to pilot input.
Regardless of what actually happened it was a great tragedy. RIP and sympathy to all involved.
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PPRuNe Radar
ATC Forum Moderator
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ironbutt57
3rd Nov 2000, 00:18
Air disaster.com I BELIEV had posted the atc transcripts...they had the aircraft under control, had apparently experimented with flap settings to test controllability for landing, when that flap setting was retracted control was lost, it would seem the loading on the horizontal stab changed suddenly causing it to shear it's physical stops..allowing the stab to travel outside limits that could be overridden with elevator inputs...
Ironbutt57,
They also have the .wav file of the accident. Very sobering to listen to and a type of RT exchange I pray I never have to undertake.
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10 West
UK ATC'er
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Shore Guy
20th Nov 2000, 14:27
the latest (as of Nov. 19)
http://archives.seattletimes.nwsource.com/cgi-bin/texis/web/vortex/display?slug=alas19&date=20001119