The Boeing Scenario Debunked
Ask any pilot old enough to remember TWA 841 and most will recite something along the following line: that’s the one where the pilots were fooling around in the cockpit with flaps and slats and circuit breakers and almost crashed then tried to cover it up by erasing the CVR. That’s the story I heard and believed until I started work on this book.
It’s one thing to read or talk about a theory; it’s a whole other thing to actually see a demonstration of that theory. On this 35th anniversary of the TWA 841 incident, I’m going to once and for all debunk what has become known as the Boeing Scenario.
The theory of what caused TWA 841 to roll over and plummet some 39,000 feet was first proposed in the summary section of Boeing’s initial report on the incident — thus the name the Boeing Scenario. The scenario is based on four assumptions:
- The upset was caused by the extension of the #7 slat in isolation
- It’s impossible for a slat to extend on its own.
- The upset occurred in close proximity to the flight engineer (FE) leaving the cockpit and returning
- The crew erased the CVR in an attempt to cover up their actions
Let’s start with assumption one – the upset was caused by the #7 slat in isolation. Simulator tests have shown that when the #7 slat is extended in isolation the aircraft is easily controllable. A 727 was flown to an altitude of 35,000 feet with the number 7 slat purposely rigged in an extended position. The flight test was ended prematurely due to the pilot’s concerns over severe buffeting.
Assumption two – it’s impossible for a slat to extend on it’s own. A review of the maintenance records of the 727 support this assumption. There were incidents involving unintended extensions of slats with a different slat actuator. There is no evidence of unintended slat extension involving the Ronson actuator.
Assumption three – the upset occurred in close proximity to the FE leaving and returning to the cockpit. This assumption was disproved during testimony given on January 29, 1980. Gary Banks did leave the cockpit to return the meal trays, but he did so some thirty minutes prior to the upset.
Assumption four – the crew erased the CVR in an attempt to cover up their actions. The truth is that the CVR was never tested. There were no tests done on the operation of the erase button to see if it was even possible for the crew to have erased the CVR due to the damage done to the electrical wiring around the gear.
The NTSB spent two years trying to prove the Boeing Scenario. During those two years they could not find a single commercial airline pilot who knew of the procedure or knew of anyone who had performed the procedure. The truth is that the Boeing Scenario is a maintenance procedure and no pilot would have any reason to ever perform it under any circumstance. The stated goal of the procedure was to improve performance. A flight test showed that performance decreased when the procedure was implemented. Furthermore, FDR data from the very same flight test showed no correlation to the FDR traces from TWA 841. The NTSB explained away this discrepancy by claiming that the FDR data was skewed because a different type of autopilot was used and a switch on a recording device was left in the test position. Furthermore, everyone on board the flight test reported severe buffeting with some calling it “startling” when all four slats were extended. No one on TWA 841 reported a similar type of severe buffeting.
But even if you discount the discrepancies mentioned above, there is a problem of simple logic. This was the first trip Hoot had made as captain after being off the aircraft for eighteen months. Would a pilot on his first trip back after an eighteen month absence play around with flight controls on a commercial flight with passengers, at night, at 39,000 feet?
Even if one of the pilots knew exactly how to do this procedure, they would have had to convince the other pilot to try something that not only exceeded the limitations of the aircraft but was also extremely dangerous. They would have to have had this discussion and then do the procedure all in the time it would have taken Gary Banks to leave the cockpit, have a few words with the flight attendant, and then return.
Finally, the procedure only works if Gary Banks returns, sees a popped circuit breaker in a darkened cockpit, then decides to push in the circuit breaker without saying anything to either pilot.
When it came time to write the final NTSB report, the author of the report, Dean Kampschror, who was also the Investigator-in-Charge, decided to remove any mention of the Boeing Scenario. You won’t find anything in the report about pulled circuit breakers or the Boeing Scenario. Instead, the report claims that the slat extended due to “the flight-crew’s manipulation of the flap/slat controls.” There is no explanation of why the crew manipulated the controls. There is no explanation of why after having manipulated the controls the crew then lost control, other than to say that the captain made untimely corrective control inputs and both pilots became spatially disoriented.
If none of this convinces you that the NTSB got it wrong, then I ask that you watch the video below. My goal is to present the facts and let the reader come to their own conclusion.
The video below contains a lot of technical jargon that non-aviation readers might not understand. It will make a lot more sense if you know that slats are leading edge wing devices that extend out and down and flaps are trailing edge wing devices that also extend out and down. These devices increase wing camber and make it possible for the plane to still produce lift at slower airspeeds, which is needed for takeoffs and landings.
One last note: This video was made possible due the help and cooperation of Hallmark College in San Antonio, Texas. I’d like to thank the following individuals: Donald Jay Gregson, Mark Lewis, Jack Kotlarz, and James Huron.