Tom_Murphy
Member
Following the BOEING 737-MAX8 grounding has made me realize how similar plane accidents are similar to Lost Hiker incidents.
Typically a series of poor decisions leading to a tragic event. Lots of speculation by non-participants with biases and agendas. Facts / report take a long time to be issued to the Public.
The Seattle Times is a very good resource for this.
And now my non-participant speculation with bias and agenda......
This accident had nothing to do with the autopilot. The MCAS is not the same as the autopilot. The MCAS is still active when the autopilot is off.
The pilots didn't recognize the situation, repeated activation of MCAS due to faulty AOA sensor, as analogous to a stabilizer trim runaway failure.
From what I have read, STAB TRIM CUT OFF is easy to do and all 737 pilots are trained on this action in response to to STAB TRIM RUNWAY.
So the last step of the two tragedies was a failure by the pilots to recognize the MCAS AOA failure situation as similar to STAB TRIM RUNAWAY.
The MCAS logic "reset" each time the pilot stopped pulling back on the column and then the faulty AOA sensor would cause the MCAS trim the stabilizer down even more
A true STAB TRIM RUNAWAY condition would present differently, the trim wheel (not sure if that is the proper term) would have been spinning rather than the intermittent and incremental turns the MCAS was causing.
How could this have been avoided?
1. better pilot training on the MCAS system by AIRLINE and/or possibly better MCAS training material BOEING
2. pilot training on a 737-MAX8 simulator by AIRLINE
3. FAA requirement that 737-MAX8 required additional pilot training [type training?]
4. purchase by AIRLINE of of OPTIONAL BOEING software to alarm if the two AOA sensors disagree
5. BOEING having that AOA DISAGREE alarm software as standard; I really struggle to understand how this feature was withheld as an upgrade especially since only one of the AOA senors was used in the control logic
6. BOEING using redundant AOA sensor in the MCAS software instead of one indication & control and the other indication only; IMO this decision is the one that is causing a lot of the "poor FAA oversight / BOEING controls the FAA" articles
7. BOEING limiting the number of times the MCAS activates. I don't think BOEING could have reduced the amount it moves the trim otherwise it wouldn't have prevented stall when activated properly. Maybe limiting the number would have been problematic to proper MCAS operation as well
8. BOEING changing the airplane design, after discovering the 'nose up' issue due to the mounting location of the larger engines on the existing frame, rather than implementing a software fix (the MCAS)
9. BOEING deciding to design more fuel efficient airplane 5-10 years earlier rather than being forced to play catch up with AIRBUS
Typically a series of poor decisions leading to a tragic event. Lots of speculation by non-participants with biases and agendas. Facts / report take a long time to be issued to the Public.
The Seattle Times is a very good resource for this.
And now my non-participant speculation with bias and agenda......
This accident had nothing to do with the autopilot. The MCAS is not the same as the autopilot. The MCAS is still active when the autopilot is off.
The pilots didn't recognize the situation, repeated activation of MCAS due to faulty AOA sensor, as analogous to a stabilizer trim runaway failure.
From what I have read, STAB TRIM CUT OFF is easy to do and all 737 pilots are trained on this action in response to to STAB TRIM RUNWAY.
So the last step of the two tragedies was a failure by the pilots to recognize the MCAS AOA failure situation as similar to STAB TRIM RUNAWAY.
The MCAS logic "reset" each time the pilot stopped pulling back on the column and then the faulty AOA sensor would cause the MCAS trim the stabilizer down even more
A true STAB TRIM RUNAWAY condition would present differently, the trim wheel (not sure if that is the proper term) would have been spinning rather than the intermittent and incremental turns the MCAS was causing.
How could this have been avoided?
1. better pilot training on the MCAS system by AIRLINE and/or possibly better MCAS training material BOEING
2. pilot training on a 737-MAX8 simulator by AIRLINE
3. FAA requirement that 737-MAX8 required additional pilot training [type training?]
4. purchase by AIRLINE of of OPTIONAL BOEING software to alarm if the two AOA sensors disagree
5. BOEING having that AOA DISAGREE alarm software as standard; I really struggle to understand how this feature was withheld as an upgrade especially since only one of the AOA senors was used in the control logic
6. BOEING using redundant AOA sensor in the MCAS software instead of one indication & control and the other indication only; IMO this decision is the one that is causing a lot of the "poor FAA oversight / BOEING controls the FAA" articles
7. BOEING limiting the number of times the MCAS activates. I don't think BOEING could have reduced the amount it moves the trim otherwise it wouldn't have prevented stall when activated properly. Maybe limiting the number would have been problematic to proper MCAS operation as well
8. BOEING changing the airplane design, after discovering the 'nose up' issue due to the mounting location of the larger engines on the existing frame, rather than implementing a software fix (the MCAS)
9. BOEING deciding to design more fuel efficient airplane 5-10 years earlier rather than being forced to play catch up with AIRBUS
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