Originally Posted by PEI 3721
CONSO ‘why the AoA option’ … , - more associated with the optional AoA display on EFIS
What value would this alert contribute to a MACS situation; ‘a good idea’, or ‘it will help confirm the situation which can be deduced from several other features’.
Alternatively it could be a further distraction in a situation which might be overly biased towards AirData (especially flap down), and a continuing, mind sapping, situation biasing stick shaker.
Let me try to answer this differently.
When the aircraft rotated, the stick shaker activated. Invalid activation of the stick shaker is of itself an unnecessary hazard for a number of reasons and has caused accidents in the past.
Let me try to summarize what I believe I know about this AOA system
The 737 has two AOA vanes and does not do comparisons between sensors. Instead the port side vane controls the captain's stall warning and inputs to the ADIRU for the left side. The starboard AOA vane controls the right seat stall warning and inputs to the right side ADIRU.
The reference AOA sensor for MCAS on the MAX apparently swaps between sides based on WOW switch activation but the sequence can be thrown off by maintenance activity.
Problem number one is that the crew does not know that AOA mismatch is in play. They need a warning to know this critical piece of information. This warning should not be optional equipment.
Problem number two, once the crew realizes that AOA mismatch is in play, they need a means to deal with it right now.
Solution: Give each pilot a push button to switch the active stick shaker and MCAS to the opposite AOA vane and peace and quiet descends in the cockpit, (provided the switches are logically located and crews trained in their use.)
Then execute UAS procedures, and write the gripe up at destination.