Reply to post: Re: Hey software, get the fuck out of the way!

Boeing 737 pilots battled confused safety system that plunged aircraft to their deaths – black box

Anonymous Coward
Anonymous Coward

Re: Hey software, get the fuck out of the way!

"there is NO reason whatsoever for software written by blithering idiots to override and countermand the pilot."

The problem is a little more subtle than a lot of news articles are spewing (and it's that sublety that made it so deadly.)

The software never "overrode" the pilots. MCAS is designed as an assist. It trimmed nose down at an inappropriate time, certainly, due to a bad sensor. But the pilots were able to trim the nose back up easily. In fact, MCAS gets "out of the way" as soon as a pilot makes a trim adjustment and stays out of the way... for five seconds. Then it tries again. It's trying to help.

The tragic flight was a game of back-and-forth. MCAS trimmed down. Pilot trimmed up. Wait five seconds. Repeat 20+ times. Then, for some reason, they didn't. MCAS served the ball, but the pilots didn't return it. We don't know why.

The pilots could have disabled all electric trim and adjusted it with the manual trim wheels. This is exactly what the previous flight on this exact airplane did. We still don't know why these pilots didn't do that.

The condition they faced is called a "runaway stabilizer" and turning off electric trim is part of the checklist on how to deal with it. The issue is that a typical runaway stabilizer is *continuous*, but MCAS does that whole "wait 5 seconds" bit which was undoubtedly confusing. There's still a lot of missing information here.

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