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A commonality in AF 447 and the two MAX cases: angle of attack is not displayed to the pilots. A substantial difference between them, is automation had totally
by cmurf 8y ago
A commonality in AF 447 and the two MAX cases: angle of attack is not displayed to the pilots.
A substantial difference between them, is automation had totally checked out in the 447 case, whereas in the MAX cases automation took action contrary to reality.
I let the engineers argue over redundancy. As a pilot I think it's a factor, but far less so than the pilots being denied knowing their airplane.
447 pilots had not undertaken any in-flight training, at high altitude, for the “vol avec IAS douteuse” procedure or on manual aeroplane handling; while the MAX pilots had no training expressly on MCAS upset so they could experience the exact consequences of ensuing mistrim, the difficulty of solving that mistrim at low altitude, and the aggressiveness of MCAS in any subsequent nose down. MAX pilots are additionally denied knowing about the true pitch up tendency in high angles of attack without the benefit of MCAS (either it wrongly thinks AOA is OK, or stab trim is cutout).
The Ethiopian Airlines pilots had the situation progressing toward stability. They had (apparently) re-enabled electric trim to give them enough authority to reset the trim, and had a sane attitude. But then within seconds they lost their chance as MCAS took incredibly aggressive action that put them in an unrecoverable 40 degree nose down attitude.
There really is no substitute for training. I don't accept that the "fix" for the MAX is a software update alone. Simulators must be capable of showing various kinds of MCAS working, not working, and perturbed (erroneous sensor input) cases, at various phases of flight. All the excuses to avoid training are bullshit.
- cjbprime 8y ago> MCAS took incredibly aggressive action In what way was it aggressive? Do you mean that it moved the trim by more than the (IIRC) 2.5 degrees per iteration it had been doing regularly?
- cmurf 8y agoYes it was 1.3 units of change inside of 5 seconds, without respect to being just over Vmo (maximum operating speed). If a human pilot did that in the same situation, it would be considered incompetency or sabotage. Shown on the same page at the same time, vertical acceleration went very slightly negative as a direct result of this MCAS nose down change. Everyone came off their seat, including the pilots, and at that same time you see yoke position changes downward (less nose up to be exact) which made matters worse even though they were already doomed at that point.
- pedasmith 8y agoThe real question is: what training would you drop in order that the pilots get this alternate training? You can't just say, "train train train"; eventually the pilots have to actually fly.
- cmurf 8y agoAbsurd for three reasons: - You've produced no evidence these pilots are at any training limit, you just made that up, so I call bullshit. - I'm a pilot and a former flight instructor so I have some credibility in refusing a binary choice like you've proposed. It's not that much training. I had to do difference training for checkouts on a regular basis (giving it and receiving it) and it's not high quantity training, it is high quality training. - The strongest argument there's plenty of opportunity for training is the fact the MAX had the same type certification as the previous NG model series. So what's the worst case scenario for difference training? It'd require an aircraft type certificate, which will require pilots undergo training and checkout for an additional type rating. Quite a lot of pilots have multiple type ratings, it's not unusual, in fact the pilot of Ethiopian Airlines 302 had type ratings for B737-7/800, B757/767, B777, and B787. What, was he only training and never flying?
- brandonjm 8y agoA fourth reason: Wouldn't a pilot rather spend some time to train for a new potential issue than not know what to do when that issue came up?
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