141–150 of 194 posts
This video from "Mentour pilot" has been deleted (supposedly upon request from boeing): https://www.youtube.com/watch?v=EzgBft-79U8 You can see it here (european version of youtube): https://vimeo.com/329558134 Or more info here: https://news.ycombinator.com/item?id=19627525
Vimeo is based in NYC USA, how is it "European version of YouTube"?
It should be noted in the doomed Air France 447 flight, the plane activated the stall warning because of a high angle of attack that was leading to stall. (thanks pdx for the corrected info) At some point the system rejected the data and stopped the stall warning because the angle of attack was so severe that it considered the data erroneous. This is speculated to have caused the co-pilot to keep pulling back on the…
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.
With all due respect, this sounds too much like the kind of armchair quarterbacking that routinely appears on HN when avionics/politics/astronomy is mentioned, where a lone programmer feels competent enough to criticize an industry for missing "something obvious". I mean, this particular change might have saved the particular 737, but I'd rather hear it from someone who actually knows how 737s fly.
I'm not going to ignore a well thought out point because someone doesn't have a PhD in the exact question under rumination.
And "armchair quarterbacking" tends to translate to "Request For Comment" in my book. I.e. a coming together of disparate ideas and areas of expertise to more fully render the extent of a problem.
Earlier quoted context omitted.
Fascinating. But it seems like the kind of scenario that would be odd for the pilot, no? You nose down, a stall warning goes off, so you nose back up again? That's exactly the opposite of what a pilot would be trained to do, right? I'd imagine in a car, if my vehicle warned me that I was going too fast when I slowed down, my reaction wouldn't be to speed the vehicle back up to avoid the warning...
I recall sleep deprivation was found to be a factor in the Air France crash. The pilots weren’t thinking clearly.
It should be noted in the doomed Air France 447 flight, the plane activated the stall warning because of a high angle of attack that was leading to stall. (thanks pdx for the corrected info) At some point the system rejected the data and stopped the stall warning because the angle of attack was so severe that it considered the data erroneous. This is speculated to have caused the co-pilot to keep pulling back on the…
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 n…
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?
It should be noted in the doomed Air France 447 flight, the plane activated the stall warning because of a high angle of attack that was leading to stall. (thanks pdx for the corrected info) At some point the system rejected the data and stopped the stall warning because the angle of attack was so severe that it considered the data erroneous. This is speculated to have caused the co-pilot to keep pulling back on the…
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 n…
It should be noted in the doomed Air France 447 flight, the plane activated the stall warning because of a high angle of attack that was leading to stall. (thanks pdx for the corrected info) At some point the system rejected the data and stopped the stall warning because the angle of attack was so severe that it considered the data erroneous. This is speculated to have caused the co-pilot to keep pulling back on the…
Earlier quoted context omitted.
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 n…
> 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?
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.
Earlier quoted context omitted.
Philip Greenspun is a highly experienced pilot: https://philip.greenspun.com/flying/milestones
He doesn't seem to be an experienced owner of a home outdoor thermometer though. Or if he is, I need to know where he found one that goes to 452 degrees and why he even needs that much range. ;)
Earlier quoted context omitted.
His proposal makes no sense. Under his new logic, it would be fine for the MCAS to continue forcing the trim to full deflection and crash the plane if the AoA was stuck anywhere between 15 and 24 degrees. He's simply not solved the root problem and added a bad kludge for a single error case (AoA stuck > 25 degrees). While at the same time removed a potential safety control for a real world case where the AoA was vali…
It is difficult to be sure from the flight data chart that was published in the Seattle Times, but it looks possible that the faulty AofA reading was below 25 degrees for most of the Lion Air flight. Reading between the lines, Greenspun has presented these crashes as "the first mass killings by software". That claim looks clearer if you present it as wholly due to the absence of a few common-sense lines of code, and…
At the altitude and airspeed at the time this last nose down was commanded, it can lead to only death, it's not recoverable, so yeah mass killing by software is not an extreme claim.