Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
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Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#2This appears to answer the question of why, given that there is a "memory item" for dealing with runaway trim that would have helped, it wasn't followed by the crew:
> “They didn’t seem to know the trim was moving down,” the third source said. “They thought only about airspeed and altitude. That was the only thing they talked about.”
If this is true, not only did the pilots not realize the trim was the cause of the dive and try to fix it, it seems that they didn't even realize the trim wheel was moving.
"Runaway trim" would be something they trained for, but has a presentation so vastly different (of a visibly spinning trim wheel causing quick descent) as to not be recognizably the same emergency to these pilots.
Of course, this crew had no way of knowing that there was a system on the plane that could slowly make erroneous trim changes over a long period with autopilot off, and it makes sense that they might miss it happening while focusing on their stall alerts and speeds and trying to come up with an explanation and also trying to retain control.
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#3This appears to answer the question of why, given that there is a "memory item" for dealing with runaway trim that would have helped, it wasn't followed by the crew: > “They didn’t seem to know the trim was moving down,” the third source said. “They thought only about airspeed and altitude. That was the only thing they talked about.” If this is true, not only did the pilots not realize the trim was the cause of the d…
Was the trim wheel not visibly spinning out of their control? Simply because the symptoms are different should mean that stopping it via taking manual control is a recurring option.
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#4In the other news, on the previous day on the same plane there was a retired pilot flying in cockpit who correctly diagnosed problem & told how to disable malfunctioning system: https://www.bloomberg.com/news/articles/2019-03-19/how-an-ex...
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#5I'm trying to imagine the horror the pilots (and passengers) were feeling. Imagine your car slowly starting to shift sideways into incoming traffic, and no matter how hard you pull the steering wheel, you can't get it back. Horrifying.
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#6This appears to answer the question of why, given that there is a "memory item" for dealing with runaway trim that would have helped, it wasn't followed by the crew: > “They didn’t seem to know the trim was moving down,” the third source said. “They thought only about airspeed and altitude. That was the only thing they talked about.” If this is true, not only did the pilots not realize the trim was the cause of the d…
Was the trim wheel not visibly spinning out of their control? Simply because the symptoms are different should mean that stopping it via taking manual control is a recurring option.
The spin was not visible to these pilots presumably because it was happening in small increments with a delay between them.
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#7In the other news, on the previous day on the same plane there was a retired pilot flying in cockpit who correctly diagnosed problem & told how to disable malfunctioning system: https://www.bloomberg.com/news/articles/2019-03-19/how-an-ex...
That's the most amazing revelation to me so far. The same plane had an identical uncontrolled-dive problem the day before, which required an emergency power cut to the improperly-engaged motor, and somehow that incident didn't ground the plane or even result in any effective advisory to the next crew.
Further, the Bloomberg story reports:
"The Indonesia safety committee report said the plane had had multiple failures on previous flights and hadn’t been properly repaired."
Lots of blame to go around here.
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#8In the other news, on the previous day on the same plane there was a retired pilot flying in cockpit who correctly diagnosed problem & told how to disable malfunctioning system: https://www.bloomberg.com/news/articles/2019-03-19/how-an-ex...
It's mentioned it the OP article:
"The cause of the Lion Air crash has not been determined, but the preliminary report mentioned the Boeing system, a faulty, recently replaced sensor and the airline’s maintenance and training.
On the same aircraft the evening before the crash, a captain at Lion Air’s full-service sister carrier, Batik Air, was riding along in the cockpit and solved the similar flight control problems, two of the sources said. His presence on that flight, first reported by Bloomberg, was not disclosed in the preliminary report."
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#9This appears to answer the question of why, given that there is a "memory item" for dealing with runaway trim that would have helped, it wasn't followed by the crew: > “They didn’t seem to know the trim was moving down,” the third source said. “They thought only about airspeed and altitude. That was the only thing they talked about.” If this is true, not only did the pilots not realize the trim was the cause of the d…
Was the trim wheel not visibly spinning out of their control? Simply because the symptoms are different should mean that stopping it via taking manual control is a recurring option.
I doubt it would have been "out of control", it would have just been slow changes over time as trim increased. The pilots might not have been fighting it much either, if they thought that airspeed was the problem, and not pitch.
Re: Cockpit voice recorder of Lion Air jet depicts pilots' frantic search for fix
#10One of the factors that has been quickly glossed over is the low level of experience of some of the pilots in both the Indonesian and Ethopian accidents. In the USA, due to much higher levels of experience pilots have been correcting for the MCAS actions effectively and complaining about it to NASA (in order to avoid being branded as whistle-blowers by their airlines).