... 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
Failure - Interactions
... NTSB blames the extension on the crew,
but does not go into detail
about exactly how it happened.