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Comment by weaksauce | Hacker News Reader

I think it's worth reporting on because this particular issue is known to everyone... you need to cycle the power on the planes every 3 days or else the reset themselves. it's crazy that a modern plane needs to have that happen but it does. the most likely situation is that the plane didn't get shutdown and happened to occur at a level flying situation and the pilots probably freaked out and overflew the plane which got it into upset territory. the plane was trimmed and would have been fine if the pilots(likely) didn't do what they did.

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Unless you're a pilot I'm not sure why anyone would expect that to be common knowledge.

And it's insane such a system would ever be authorized IMO. That sounds like a hack to fix a memory leak or similarly some bug they can't figure out

I'm working on an aircraft program right now. We have a requirement to power cycle the plane every N days. It's in the manuals.

Why?

> Why?

Radiation-induced bit flips and bad code.

Simple: we have timer counters in the code. This is easier than handling them rolling over.

>Unless you're a pilot I'm not sure why anyone would expect that to be common knowledge.

It should sure as hell be common knowledge to the pilots of the plane. I would have expected something like this to be on a checklist somewhere though: "Step 74, check uptime in Flight Computer, pull breaker if too high"

Why would it be insane for a computer controller of what is essentially industrial machinery be designed to be reset at least once every other day? They "reboot" the engines damn near once a flight! Most pilots have experience and training on shutting down a plane for say overnight and then starting it from cold and dark the next day.

It's an odd idea to us software developers but the computer isn't the primary function of the plane, and doesn't need to serve customers 24/7. If the computer is 100% reliable only for 18 hours, and the plane cannot fly for longer than 12 hours in the first place, is that a problem?

  > If the computer is 100% reliable only for 18 hours, and the plane cannot fly for longer than 12 hours in the first place, is that a problem?

It is a problem if it requires a human to remember to do the procedure, especially if it is not done on every flight. Putting it on the checklist, but making it optional per situation, is asking for someone to make a mistake.

The reset should happen on every flight, if forgetting it on the wrong flight could potentially lead to an incident.

>pilots probably freaked out and overflew the plane

I've got a pilots license and shoving the stick forward such that you pull negative Gs and passengers get stuck on the roof is not a normal reaction to the instuments going out.

It sounds more like one of the computer systems crashed or lost power causing a lack of control until a backup kicked in, and caused the fly by wire to pitch downwards briefly.

There was a mandatory patch for that in 2020.

It apparently wasn't mandatory - you could ignore patching it if you kept doing the "reboot at least once every 22 days" directive from the AD 2016...

> the most likely situation

What is the value in posting a long, entirely speculative comment like this? It doesn't even appear that you have any credibility in this field. Even if you did, this comment would be useless.

> you need to cycle the power on the planes every 3 days or else the reset themselves

Huh? Try 51. https://news.ycombinator.com/item?id=33233827

Some A350s needed a reboot every 149 hours (6 days) for a while.

https://gizmodo.com/turn-it-off-and-on-again-every-149-hours...

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