Comment by TimTheTinker | Hacker News Reader

Comment by TimTheTinker | Hacker News Reader

My family (wife and kids) and I have a scheduled flight on a Southwest 737 MAX this week. I'm worried about whether there's an unacceptable risk involved in flying on a 737 MAX because of this morning's crash (and last year's Lion Air crash).

After a bit of googling, I found this article from November 2018: https://theaircurrent.com/aviation-safety/southwest-airlines... Apparently, Southwest has been updating glass cockpits in its 737 MAX fleet to include extra indicators to mitigate factors that led to the 2018 Lion Air crash, like an on-screen AOA indicator and a warning light to indicate when AOA sensors don't agree. (I do wish they had gone far enough to disable the MCAS system when one AOA sensor indicates high AOA and the two sensors disagree by more than 2x their individual tolerance.)

That mitigates our risk in the chance that the crash was caused by the same factors that led to the 2018 Lion Air crash, but I'm still nervous as the cause of this morning's crash is unknown.

I am generally the person who says things like "the plane will be many times safer than the car ride to get to the airport", and I would cancel that flight. (And I would further be shocked if the FAA doesn't issue a ground suspension of the MAX tomorrow.)

And hey, Southwest gives full credit for cancellations, right?

The Lion Air crash was world news. If any 737 pilot heard about it, presumably went through extra training in its aftermath, and yet was unable to avoid the exact same takeoff->unreliable airspeed->stall pattern, then it's simply not possible to rely on piloting to avoid stalling the plane. As far as I know this Ethiopia crash was in visual conditions: the pilots could see the ground, which means they weren't confused about what their AoA was. I'm not an expert, but I think control failure of the airliner under these conditions is basically unprecedented.

There's a planned MCAS software update that's been delayed for months: after that actually ships seems like the right time for people to start flying the plane again.

https://www.wsj.com/articles/boeing-and-regulators-delay-jet...

Visual flight conditions give you your angle relative to the horizon but not necessarily AoA especially in non-normal flight conditions (like steep ascent or descent).

https://www.bloomberg.com/opinion/articles/2019-03-10/ethiop...

> A software update intended to fix the problem identified in the Lion Air crash still hasn’t been rolled out. The fact that the crew on Flight 610 are likely to have been aware of the known issues with the aircraft, too, raises the more worrying possibility that there’s an unknown complication.

https://theaircurrent.com/aviation-safety/what-is-the-boeing...

> The relocated engines and their refined nacelle shape caused an upward pitching moment -- in essence, the Max's nose was getting nudged skyward... putting the aircraft at risk of stalling, according to a series of questions and answers provided to pilots at Southwest Airlines. The Maneuvering Characteristics Augmentation System(MCAS) was designed to address this.

Reply on news.ycombinator.com