Originally Posted by
Aihkio
So nobody thought what would happen when the duty AoA sensor misbehaves for some reason, like getting stuck at lets say 25 deg. Multiple warnings and an activated MCAS. Maybe all primary sensors should be analysed.
Boeing made a deliberate design decision to NOT compare AoA signals or do any other processing of the data. The reasons has been fully documented on pprune.org and the Wall Street Journal, search for Rick Ludtke.
The bullet points are:
- Comparing AoA signals could generate a warning.
- AoA warning would be outside an iPad training path for 737NG--->737MAX and could possibly involve a simulator session.
- A simulator session would incur a $1 million penalty per aircraft for Southwest airlines.
- Boeing choose to categorise an uncommanded MCAS runaway as only "major" and not hazardous
- Therefore Boeing choose not compare AoA
The design failures between a single faulty AoA sensor and continuous MCAS activation have not been fully revealed.