Ethiopian 737 MAX 8 crash
#581
Disinterested Third Party
Joined APC: Jun 2012
Posts: 5,926
I was referring to the data from the ET302 accident report. However it's clear now: the air data computer corrects the static and pitot pressure for AoA, and since the AoA was incorrect, the airspeed and altitude were wrong too.
There's an article in AvWeek today by Fred George, where he explains it like this: "AOA is used by the aircraft’s air data computers to correct pitot and static pressure variations induced by changes in nose attitude in relation to the relative wind. Large errors in AOA can cause 20-40-kt. errors in IAS and 200-400-ft. errors in indicated altitude."
There's an article in AvWeek today by Fred George, where he explains it like this: "AOA is used by the aircraft’s air data computers to correct pitot and static pressure variations induced by changes in nose attitude in relation to the relative wind. Large errors in AOA can cause 20-40-kt. errors in IAS and 200-400-ft. errors in indicated altitude."
In the Ethiopian mishap, yes, there was an airspeed difference, caused by incorrect AoA data. It was on the left side only, and the crew determined that to be the case. The crew verbalized the problem with the left AoA, and knew they had an airspeed difference.
The failed AoA input did not affect the left side or the standby instrumentation. It's for that reason that the standby indication is uncompensated and is independent.
#582
Gets Weekends Off
Joined APC: Dec 2005
Posts: 8,883
J Burke, your signature line haha. You'll like this:
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#584
Gets Weekends Off
Joined APC: Mar 2013
Position: 737 FO
Posts: 269
MCAS can not be turned off. The electronic stabilizer trim can be turned off rendering MCAS useless. The preliminary report shows MCAS commanding nose down trim even after the switches were off but the trim did not move. The reason they could not control the aircraft at that point was because they were above the maximum operating speed for the aircraft and manual trim is nearly impossible to use with those aerodynamic loads.
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#585
Disinterested Third Party
Joined APC: Jun 2012
Posts: 5,926
#586
New Hire
Joined APC: Apr 2019
Posts: 1
Thank you to all those that have contributed to this thread. I think the following article may be a little optimistic but sounds like things are happening.
The FAA has called a crucial meeting of the heads of civil-aviation authorities from around the world for May 23, where the U.S. regulatory agency is expected to outline its finalized safety analysis in an attempt to foster international consensus.
https://www.seattletimes.com/busines...or-early-june/
The FAA has called a crucial meeting of the heads of civil-aviation authorities from around the world for May 23, where the U.S. regulatory agency is expected to outline its finalized safety analysis in an attempt to foster international consensus.
https://www.seattletimes.com/busines...or-early-june/
#587
"Boeing Whistleblowers Report More 737 MAX 8 Problems to FAA"
https://interestingengineering.com/b...roblems-to-faa
https://interestingengineering.com/b...roblems-to-faa
#588
"Boeing Whistleblowers Report More 737 MAX 8 Problems to FAA"
https://interestingengineering.com/b...roblems-to-faa
https://interestingengineering.com/b...roblems-to-faa
#589
I thought it was very odd that two new airplanes had already experienced AOA failures. In my 25+ years of flying I've never experienced one nor heard a friend having one.
#590
In a land of unicorns
Joined APC: Apr 2014
Position: Whale FO
Posts: 6,403
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