LATAM 787 Sudden Drop due to 'Technical Incident'

[Evan]

SUPPOSEDLY:

Hostie brings pilots “the fish.”

They bump a guarded switch on the back of the pilot seat.

The pilot seat begins moving forward.

Shoves the pilot into the control column.

Dive ensues.

Commentary:

It’s a completely different kind of MCAS, altogether.

IF TRUE:

I take back my expectation about a deep dive into 787 systems. This is pathethic.

[Gabriel]

It's a completely different kind of MCAS, altogether.

It's a completely different kind of MCAS

[Evan]

The 787 has an additional seat track switch hidden under a plastic flap on the top of
the seat back. If that flap is missing or is stuck in the open position, I can easily see how a FA can inadvertently hit it while bracing a hand against the seat back. If this happened, I would expect an emergency AD requiring inspection of this flap guard.

In the longer-term, I would require a modification that disables this switch when the pilot is seated.

[Evan]

It's a completely different kind of MCAS

It’s a completely different kind of pitch trim switch.

[3WE]

It’s a completely different kind of pitch trim switch.

Electric motor works a mechanical linkage to a control surface…arguably conventional setup…(yes, the font might be a tad blue.)

[Evan]

Some further clues here:

In a message to 787 jet operators that was sent late Thursday, Boeing said it was advising of a “known condition related to a loose/detached rocker switch cap” located on the seat back of the captain’s and first officer’s seats but did not say whether the switch covers had played a role in the incident on the Latam plane.
“Closing the spring-loaded seat back switch guard onto a loose/detached rocker switch cap can potentially jam the rocker switch, resulting in unintended seat movement,” Boeing said.

The memo, a copy of which was reviewed by The New York Times, pointed to the 2017 letter, which noted the installation of adhesive to the rocker switch caps “to prevent the caps on the rocker switches from detaching and/or becoming loose.”
Boeing recommended all operators of 787 planes to inspect the four rocker switches and rocker switch caps on the seats.
The Wall Street Journal first reported that Boeing had sent the memo to airlines.
In a note to its 787 flight crews, American Airlines said it had “identified a potential hazard” with the horizontal power control switches on the top back of pilot seats.
The note, which was reviewed by The Times, said that the airline’s technology operations team “will be ensuring that these switches are properly secured” and asked 787 captains “to brief all pilots, flight attendants and flightdeck jumpseat riders on your flight of the importance of not using the switch on the top back of the pilot seat when the seat is occupied.”

Why do I think that a condition in which the pilot seat could unexpectedly and rapidly advance into the control column might be a prime candidate for a mandatory compliance airworthiness directive?

I realize that hindsight is 20/20, but why does foresight have to be -8 with astigmatism?

[Gabriel]

rapidly

Our definitions are not aligned.

[Evan]

Our definitions are not aligned.

That seat moves pretty fast. Probably 2-3 seconds from where he was to the full forward position.