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Thread: TWA Flight 841
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Old 09-21-2012, 04:34 AM   #6 (permalink)
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Default Re: TWA Flight 841

Originally Posted by MrMD11 View Post
Based on the video, I don't see how you can automatically draw a conclusion that "he caused" the situation that that flight found itself in. An erased voice recorder, in this case proved to be a double-edged sword - it could imply guilt or it could prove innocence as well.

I didn't have to watch the video as I've read the NTSB Report on TWA 841 some time ago. I've drawn my conclusions based on the report as well as my own personal knowledge(I'm an airline mechanic with some 727 experience);with a little logic and common sense throw in for good measure.

If you have time, I do recommend perusing the report. A good place to start is section 1.17.1 and 1.17.2 if you're unfamiliar with the 727's flap/slat system. The latter section probably debunks something I'm sure your video alleges - namely that failures of slat actuators are commonplace. While that is somewhat true, the failures always occur with intended slat movement(ie slats don't retract/extend when commanded, essentially causing slat disagree) and never cause uncommanded slat movement. Section 2.4, pg 23 of the report outlines what it takes to cause an uncommanded extension of a slat/slats.

My personal theory, which agrees with 95% of the report:

In cruise, the pilots employed a well known trick that increases fuel efficiency. Said trick is: 1)pulling the leading devices circuit breakers to keep the slats from extending because 2) the flaps are then set to the 1, or 2 position. At this setting, the flaps don't droop at all, they only increase wing area, providing more lift.

Either the wrong combination of breakers were pulled(more likely), or they were inadvertently reset by the FE(less likely) because the #2,3,6 and 7 slats extended with the flaps. Upon realizing the gaffe, the pilots quickly selected flaps back to zero. Slats 2,3, and 6 retracted but 7 remained extended due the aerodynamic stresses exacerbating a pre-existing misrig of the slat, causing to it to jam. The increased aerodynamic forces in the dive ripped the slat away as the airplane was doing approximately the speed of sound. Immediately after landing, the CVR was erased.

I have no dog in this fight and I'm not one prone to conspiracy theories. To the contrary, I'm a skeptic and this incident is a good application of Occams Razor.

Last edited by neilc777; 09-21-2012 at 04:38 AM.
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