Behind the Lion Air Crash, a Trail of Decisions Kept Pilots in the Dark

Actual example: Normal takeoff in instrument meteorological conditions (no external visual references, flight by reference exclusive to instruments). The attitude indicator shows proper climb attitude, vertical speed and altimeter show positive rate of climb, airspeed indicator shows speed increasing above target speed. Pilot response? Probably nose up and/or power reduction; OK they do both. Airspeed indication continues to increase. Pilot noses up and powers down. Airspeed increases. Pilot noses up aggressively. Stall. Crash.

What happened? The pitot tube and drain were clogged. Static port was clear. This turned the airspeed indicator into an altimeter - it was incapable of showing correct airspeed from the moment of blockage.

The cause of the crash is pilot error. The pilot is expected to recognize from other instruments that the airspeed indicator is unreliable, and this is part of training for instrument rating.

If the MCAS in the Lion Air crash made a similar mistake - using a single data point to determine a stall condition. That is an error. It's functionally "pilot error" to have no means of determining if the angle of attack sensor is wrong, and no mechanism for disregarding its data. Further, the corrective action it took, had the flight condition actually been true, sounds excessive. If a human pilot did the exact same thing MCAS did, I expect the human would be blamed - it would be pilot error to so aggressively nose down that you've exchanged a level flight high speed stall (a rare event indeed) for a high speed dive. That is not a competent recovery, in particular that there's apparently no recognition of the danger of high speed dives let alone recovery from them it's probably a really good idea if your stall recovery does not ensue in a dive!