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Old 10th Mar 2019, 17:41
  #140 (permalink)  
physicus
 
Join Date: May 2010
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NWA SLF Read the AD. Loss/malfunction of a SINGLE AOA sensor can result in nose down trim input being automatically applied. The fact that there’s an automated system producing flight control input is in contravention to the fundamental operating philosophy of Boeing aircraft, and it has consequentially and not surprisingly caught out the crews. It is also now evident that the MCAS system (implemented due to a certification requirement for pitch stability during high power applications like G/As) appears to have been written in a bit of a hurry, without taking the usual redundancy philosophy into account.

We don’t know whether that was a factor in this accident until FDR/CVR are located and analysed.

Airbus operating philosophy is very different, and has been proven in the past to not do anything stupid to the aircraft unless a) multiple sensor inputs have been disabled/crippled, and b) pilots do stupid stuff like resetting flight stability essential computers in-flight by getting out of their seat and pulling CBs on maintenance panels meant for ground and engineering use only.


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