3 ms·
Because right after takeoff is the single most common point at which you might stall the aircraft. What's more, at that point it is likely to be a power-on sta
by paulmd 8y ago
Because right after takeoff is the single most common point at which you might stall the aircraft. What's more, at that point it is likely to be a power-on stall, which is the specific situation that MCAS is intended to fix (because the 737 MAX has a tendency to pitch upwards in power-on scenarios).
Really there should just have been a separate cutout for MCAS itself, but that would have triggered retraining requirements, so Boeing wanted to avoid that. But very simply, there should just be an 'off' switch to disable this system if it starts to run away, distinct from the whole runaway trim procedure.
(as well as 2-of-3 redundancy on the sensors, the lack of redundancy is seriously exacerbating the rate of incorrect MCAS system activations)
- cjbprime 8y ago> is the specific situation that MCAS is intended to fix Well, not quite: if they wanted it to protect against stalls at very low altitude, it would be operational with flaps extended.
- kalleboo 8y agoAnd the AoA disagree needs to be actually used and not just an "option feature pilot warning". AoA disagree on ground = plane doesn't take off. In flight = MCAS cuts out.
- cjbprime 8y agoYou can't have an AoA disagreement when stationary on the ground. It is a wind vane.
- djmips 8y agoYou don't know that. If it's malfunctioning it could be in the electronics and nothing to do with how it operates.
- cjbprime 8y agoAnd if it's reporting a difference, it could just be because there's no airflow and the vanes aren't at identical positions. You can't rely on the difference meaning anything.