Arthur T Knackerbracket has found the following story:
Lion Air Flight 610, which took off from Indonesia on Oct. 29, should have never left the runway. On its previous flight, the aircraft gave incorrect speed and altitude readings.
But it's unclear whether the pilots were even aware that the plane had been malfunctioning. They took off at 6:20 a.m.
They immediately received the first signal that something was wrong: The control column started shaking loudly, warning that the plane was in danger of stalling and could crash.
The plane kept climbing, but the pilots could not figure out the correct altitude or airspeed, asking air traffic control for help. And two critical sensors registered different readings between the pilot and co-pilot.
Then the plane dropped over 700 feet, furthering the confusion inside the cockpit. "An aircraft dipping after takeoff is not normal. It's beyond abnormal. It's unacceptable," said Dennis Tajer, a pilot and spokesperson for the Allied Pilots Association.
Something alarming had happened: The aircraft's computer system had forced the plane's nose down. The pilots recovered from the drop, but air traffic control noted they were "experiencing a flight control problem."
(Score: 5, Informative) by Anonymous Coward on Friday December 28 2018, @12:58AM
The MCAS system activates when autopilot is OFF. Here is the link [theaircurrent.com]. The pilots should have enabled the autopilot - but the airplane was too unstable for them to do so, and they did not know that MCAS exists. Boeing omitted this system from training manuals.
The article also says that pilots could disable MCAS by trim switches on the yoke - but only for five seconds, after which the problem reappears. To disable it for good one must disable electronic control of trim and manually crank the wheel to the desired setting. As you can see, these are extremely uncommon actions, and without training pilots couldn't know what to do.