Failure - Interactions
... NTSB blames the extension on the crew,
but does not go into detail
about exactly how it happened.
... flight data recorder ... proved ... unhelpful ...
"... Pilots Association ... ALPA blamed pressure from Boeing for NTSB's rejection of possible mechanical causes . . . advanced its own hypothesis:
a worn and misaligned leading-edge Slat popped out . . . roll to the right."
Garrison accurately cites ALPA's later joining the investigative-focus on the separated #7Slat:
Mistakenly, the Pilots' Association did NOT challenge that erroneous assumption --
a Slat EXTENSION just prior to INITIAL upset.
Both the NTSB-staff and ALPA -investigators had failed to
call-into-question that erroneous assumption, that red-herring, asserted by the manufacturer, in their first
NTSB's P.C. = the Boeing Scenario.
An NTSB Err -- there is nothing in the direct evidence to support the erroneous assumption that "passing through 21,000 feet ... landing-gear extension"
Damage to components near the RHS-MLG, together with Trail-of-Debris, and Trajectory of Separated Parts, shows proper altitudes for these LG-EXTENSION failure-interactions.
The erroneous assumption:
"... the slat in the EXTENDED position ...
initially caused the airplane to roll . . ."
... analyses ... will remain in
the realm of supposition.
The NTSB version . . .
"These reports, although mentioned by one aviation publication . . ."
Yet, other aviation-publications, and general media, did allude to these vague rumors about this previously non-existent, unheard-off, "procedure" -- this rumor was an assumption, the NTSB labeled the rumor as "a finding", and the rumor was part of NTSB's P.C.
The vague rumors shortly AFTER the mishap,
B-727, N840TW, TWA841 / 4Apr79, CRZ, night, Saginaw, mysterious inflight upset, Yaw x Roll = DIVE, Loss-of-Control, pilots' EXTENDED Landing Gear, fortuitous hydraulic-failure of System-A, recovered control, 5.8-G pull-up, diverted to DTW.
Garrison's faith in NTSB-method:
he thus missed explicitly specifying the weakness in the USA's system of investigation:
The USA- method relied on the manufacturer, or the pilots' association, to help provide NTSB with the complex failure-interactions.
The pilots' association had erred, by not challenging that distraction, that "red herring" -- that mistaken assumption, that an EXTENDED- Slat was a "cause" of initial upset (mistakenly accepting an erroneous linear failure-sequence).
Yorke later showed investigators that accepted practice was to "work backward", focusing on DIRECT EVIDENCE: working from the Trail-of-Debris, Yorke offered the needed insight:
that an un-commanded
was a later "effect" -- unrelated to causes of the INITIAL upset at CRZ FL390.
"In fairness . . .
while this explanation is now the official one,
the NTSB . . . claims . . . that
alternative mechanical explanations are
too remote and improbable . . ."
"... might be called Gibson's Law,
and it deserves to be burned into the memory of all pilots . . . who find themselves plunging out of control toward the ground at night:
never give up."
Garrison, Peter. "Aftermath: In Quest of Extra Performance"
Flying Magazine. 109:3 (March 1982), p94-6