An amazing article digging into Boeing and their decisions that led directly to the first plane crash (Lion Air). Not sure how much applies to the second crash, but unfortunately probably all of it.
http://www.seattletimes.com/…A summary:
1. Boeing changed the engine locations in the 737 MAX, which created a possibility of nose up pitch (in some circumstances) as compared to the existing 737.
2. Boeing created a “secret” computer program to override the pilot and push the nose of the plane down if the angle of flight was too steep. (I call this “hidden” because pilots were not told about it and IT WAS NOT IN THE FLIGHT MANUAL.)
3. Boeing self-certified to regulators the secret computer program was acceptable and indicated it could only push the nose of the plane by less than one degree (.6 actually). The FAA granted Boeing this authority because of budget cuts and time pressure.
4. In actual flight testing, Boeing changed the computer program to allow for 2.5 degrees of movement (instead of .6 degrees). At some point, they also made the program so that it “reset.” This meant the nose could move more than 2.5 degrees in total if the computer program was triggered more than once. (In the Lion Air crash, the program was triggered to move the nose at least 23 times in quick succession).
5. Boeing used only a SINGLE SENSOR to trigger the computer program and push the nose down. In the Lion Air crash, a faulty sensor meant there was no way to satisfy the pitch angle the program was looking for — which created an INFINITE LOOP and caused the computer to continually try to push the nose of the plane down. [Imagine you were the pilots trying to figure this out under the extreme stress of crashing. After 21 rounds of fighting the system the pilot gave over control to the co-pilot, who had 2 or 3 rounds before the plane crashed].
I was going to try to summarize the lessons, etc. here — but it is too sickening and I don’t know where to start. The article is a great example of real journalism, as it is the hometown paper of Boeing and it does not pull any punches. Based on the details reported (i.e., single sensor/infinite loop problem), many people at Boeing belong in jail for homicide, in my view.