[conspire] Ethiopian Air was following the emergency checklist

[Rick Moen]

March 13th, I wrote:

> Back in November after the Lion Air disaster, FAA issued an emergency
> airworthiness directive for the 737 MAX 8 and 737 MAX 9, which, if
> these search URLs are persistent, you can read here:
> http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83ec7f95f3e5bfbd8625833e0070a070/$FILE/2018-23-51_Emergency.pdf
> 
> It highlighted the syndrome found in the Lion Air disaster where the AoA
> (angle of attack) sensor was sending erroneous angle data to the flight
> control computer's new Maneuvering Characteristics Augmentation System 
> (MCAS) circuitry that is the new component in all 737 MAX craft, that
> tries to prevent stalls by forcing nose-down trim when it thinks
> necessary.  You will note (page 4) that the revision to operating
> procedure says that, if this happens again, the pilots should (a)
> disengage autopilot (to makes sure the pilots can assert attitude
> apply trim control using the control column and regular trim controls)
> and, if runaway trim override continues, set the stabilizer trim ('STAB
> TRIM') switches to the 'CUTOUT' position (aka 'STAB TRIM CUTOUT').  The 
> latter switch position directly disables MCAS.
> 
> The relationship between the MCAS and the autopilot is almost
> incidental.  This site clarifies further:
> https://www.satcom.guru/2018/11/737-mcas-failure-is-option.html
> 
>   Manual trim command would pause MCAS for five seconds; then it would
>   pick up again.
> 
>   The Autopilot Trim Cutout switch would turn off the MCAS trim command.
> 
>   The Stabilizer Trim Cutout switch would remove power from the trim
>   motor.

News flash:  The Ethiopian Airlines Flight 302 crew did just that --
exactly following the emergency checklist.  This revelation is pretty
much fatal to Boeing Company's current narrative, which has been a claim
that pilots of the Lion Air and Ethopian Airlines flight could have 
recovered control by just switching off the misbehaving MCAS system, but
either didn't know how to disengage MCAS or did so too late (i.e., the
vendor-traditional 'blame the pilots' response).

_New York Times_ has coverage at
https://www.nytimes.com/2019/04/04/world/asia/ethiopia-crash-boeing.html :

  About a minute and a half after takeoff, after the pilots had
  performed routine tasks like retracting flaps on the wings, the false
  reading appears to have set off an automated system known as MCAS, the
  black box data shows. MCAS is intended to prevent a stall and began
  rapidly pushing the nose of the craft down.

  The pilots countered that by pushing electrical switches on their
  control wheels that adjusted the angle of stabilizers on the tail of the
  plane, which had been moved by MCAS. About five seconds after the pilots
  tried the right the plane, MCAS again engaged, moving the stabilizers to
  a dangerous angle in another nose-down action.

  The pilots pushed the electrical switches again. Then, the report says,
  they followed the emergency checklist and disabled the entire stabilizer
  electrical system using the so-called stabilizer trim cutout.

That's the key bit:  The pilots did the critical 'STAB TRIM CUTOUT'
operation -- but it wasn't enough:

  “The first officer called out ‘stab trim cutout’ two times,” the
  report says. “Captain agreed and first officer confirmed stab trim
  cutout.”

  Although that move disabled MCAS, it also forced the crew to control the
  stabilizers manually with wheels at their feet — a physically difficult
  task on a plane moving at high speed. A little under four minutes after
  takeoff, the first officer said the manual method “is not working.”

  Soon after, the black box data indicates, the crew turned electricity
  back on and tried two more times to move the stabilizers by hitting the
  switches. But once they turned the electricity back on, MCAS engaged
  again, putting the plane into a dive from which it would not recover.


The current story is the result of preliminary findings from Ethiopia's
aviation investigators, who've been working with an international team.
Immediately after the Flight 302 disaster, in a stunning repudiation of 
the (also culpable) US Federal Aviation Administration, Ethiopian
officials refused to hand over the jet's flight data recorder and
cockpit voice recorder to US officials, saying they'd rather work with
an international team, thanks very much.

A final report on the Lion Air disaster is expected in August, but one
on the Ethiopian Airlines crash is expected to take at least a year.