Hacker News Reader

Comment by seethishat | Hacker News Reader

"On the ground" = WoW sensors. WoW sensors have been around a long time (see link). And, humans probably should not have any say about that. If humans could override WoW, then the landing gear could be deployed or retracted when it should not and cause a lot of damage due to human error.

https://en.wikipedia.org/wiki/ACARS

View on HN

Yeah, when I saw that it was related to WoW sensors I was reminded of a chat that I had with an experienced aviation engineer a few years ago when we were considering adding them to the UAS I'm working on. "Every system I've ever worked on that relied on WoW sensors has had some kind of unexpected adverse event due to the sensors either triggering when they weren't supposed to, or not triggering when they should have. If you can figure out a different way to do what you're trying to do, please do."

I know the 737 allows the pilot to override that (force the wheels to raise even if the airplane thinks it's on the ground). I think most airliners do. I can't find a good succinct reference though.

EDIT: Remembered Airbus exists

this makes sense but why is the decision based only on the state of the landing gear? Is it dumb to expect altitude and speed to be considered?

No, that's not dumb at all. Inputs are filthy and sensors fail. If you're not comparing all available sensor data to confirm your understanding of reality, then a single sensor failure could... oh I dunno... cause your 737 MAX to divebomb.

The F-35 could compare weight on wheels to airspeed as a simple sanity check.

Reply on news.ycombinator.com