Originally Posted by
soarbum
Even Fox news would have trouble keeping a straight face telling that porkie...
1) Boeing knew that a step to trim back to level before hitting the cutout was not in the emergency response checklist: did they modify it - NO
2) Boeing knew that MCAS would keep coming back for another bite 5s after the last trim input but a pilot could safely use the trim if they hit the cutout within 5s afterwards: they did share that - NO
3) Boeing knew that if there was an unreliable airspeed situation after take-off, leaving the flaps out would inhibit MCAS and allow a safe landing: did they share that - NO
4) Boeing knew that they had modified the trim architecture so that the pilots first response of pulling back on the column would no longer inhibit AND trim as it did in the NG and every other 737: did they share that - NO
Interesting points - answers to all those points were extractable from the Lion Air preliminary report. I knew all those things from the report before reading the AD and FCOM update.
In retrospect I would have made the Emergency AD one line: UNTIL FURTHER NOTICE DISABLE ELECTRIC TRIM.
What you meant was that Boeing and the FAA didn't repeat the contents of the Lion Air Preliminary report in the AD. Read Appendix D of the ET-302 final report of the Multi Operator Message which was issued on 10 NOV 2018 to see what Boeing did publish.
While it might have seemed to be a secret to those who don't own or operate 737 MAX aircraft - per Appendix H, Captain Seifu (Senior Vice President of Flight Operations at Ethiopian Airlines) got a reply on Dec 3, 2018 about his inquiry over the 5 second delay on Nov 28, 2018. which he understood from a conference call with Boeing. Curiously he remarked about following the UNRELIABLE AIRSPEED procedure, which the ET-302 crew also didn't follow.
It is a puzzle - what sense is there, when one has a stall warning, to retract the flaps?
The AD does mention to use the control column and main electric trim to manage the pitch attitude and it indicates that the electric trim can be used to neutralize control column pitch forces. Clearly failing to follow the stall warning procedure, doing the opposite of what is detailed there, would anyone expect that flight training 101 instructions about neutralizing trim forces would have helped?
In the FDR it is clear that the pilots did respond with electric counter trim, within 12 seconds the first time and about 6 seconds on the second MCAS increment, but left between 60 and 100 pounds of pull on the control column, even though the electric trim was reducing the control force at the time they gave that up.
Why would a pilot not continue to trim out the excessive force? Would that have been a reasonable prediction?
More important, the AD also says, quite clearly, "ensuring the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight."
"and stay in the CUTOUT position" seems important.
Until the crew re-enabled the trim to apparently try to re-enable the autopilot (specifically an item to be disabled when a stall warning and stick shaker is running under the UNRELIABLE AIRSPEED procedure) the plane was gaining altitude, about 2000 Feet per Minute. After going against the AD they tried electric trim twice and the stabilizer moved both times, then autopilot warning was given which would have been only from pushing the enable button and then, 6 seconds after what they tried failed, MCAS ran for 4 seconds until the plane pitched down and the AoA sensor was likely in range. They did not attempt to retrim that increment as they apparently focused solely on pulling.
The main reason they had trouble with control was failing to handle the stall warning / UNRELIABLE AIRSPEED by taking full control of the wheel, control column, and throttle.
They never performed in the simulator to demonstrate solid capacity to comply with an AD issued as a direct result of a crash.
More important, no discussion about what Captain Seifu (Senior Vice President of Flight Operations at Ethiopian Airlines) did following that conference with Boeing in regards to training, discussions with his company pilots, or any other factor, appears in the Final Report. He knew about the 5 second delay - there is no evidence he told any pilot at Ethiopian.
Now that it is clear that all relevant information was supplied to Ethiopian Airline by Boeing before the ET-302 crash, all those details supposedly withheld.
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There was no requirement for Ethiopian to fly the MAX after the AD. That was a voluntary choice, to put an airplane with a latent defect into service knowing that their pilots had no follow-up training and were provided with only the AD, that the management had felt was inadequate. The lack of detail on how the unreliable airspeed training was insufficient such that two pilots with apparently recent training did every step incorrectly is troubling.
Instead of focusing on the runaway stabilizer in the AD, the crew would have been served better if training was provided about the effect of MCAS activation.
The previous sentence is from the Final report, not me, in case there was concern. The airline was responsible for providing that training.
22. While the autopilot was engaged, systems were supplied by the erroneous LH AOA values. The A/P failed to fly to the target altitude resulting in accelerated speed. After reaching a maximum altitude of around 9,100 ft (right baro corrected altitude) the Airplane started to descend;
23. The A/P disconnected automatically after remaining engaged for 32 seconds;
24. The activation of MCAS followed by GPWS aural alert with ongoing stick shaker, coupled with no failure flag or warning to indicate that the auto throttle has failed to transition to climb thrust at the critical phase of flight indicate that multiple happenings taking place simultaneously because of the overlapping effects of the erroneous AOA inputs;
25. The Stall Management Yaw Damper Computer -1 (SMYDC 1) computed a LH minimum operational speed and a LH stick shaker speed greater than VMO (340Kt) without any alert or invalidity detection;
All of this, including the autopilot and the SMYD, had traditionally been allowed to accept erroneous AoA data and caused problems the crew didn't notice. MCAS was at the end of a long line of accepting inaccurate AoA data - 30+ years of industry acceptance.
AFAIK Airbus doesn't do sanity checks on the AoA sensors, depending instead on best 2 out of 3, which has also prompted at least one incident on par with what MCAS did. That hero pilot pulled the circuit breakers to the 2 lying computers to save the plane.