MurphyWasRight
Agreed, before Lion Air suggesting that a new undocumented feature relying on a single sensor would have a death wish would have indeed been laughable.
Truly tragic is the CYA manner the AD was written, rather than simple and forcefull checklist for MCAS misbehave.
Would be interesting to hear why mention of the 'yo yo' technique was removed along the way.
Additional point:
A true trim runaway (stuck relay/whatever) at high speed could get into this state before the pilots recognized and cut out the trim motors, so hard to see how this is unimaginable. About 5 seconds or so appears to do the trick.
To their credit, I would assume that the runaway trim procedure was written considering the entire flight envelope. Statistically this would be more likely to occur at altitude, rather than close to the ground, where the aircraft spends a limited time. Not a great assumption, but in the normal scenario, there would be more time for recovery procedures.
The fact that MCAS triggered shortly after takeoff, made the outcome diabolical, when the other factors came into play. If MCAS triggered at altitude, the outcome would probably be more benign, with time for the yo-yo unloading technique.
Perhaps this lack of foresight led to the blandness of the emergency AD. Prior to ET302, almost nobody would have believed that the same outcome could be triggered by two consecutive AOA sensor failures at the same stage of flight, and disaster still not be prevented by the suggested actions.