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Comment by dehrmann | Hacker News Reader

I'm surprised commercial planes don't do full software reset before each flight, and especially before a new crew takes over. Checklists only get you so much.

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The checklists bring the aircraft back to a known state.

One 777 pilot commented to say that this issue should have been caught by at least two checklists, implying that neither checklists had been followed.

Tangentially: if my 2006 Mercedes is reset (battery disconnected) it needs to idle for 20 minutes to re-learn the idle pattern. The vehicle then needs to be driven around for a bit to re-learn driving patterns. I wonder if there are similar settings on a 777 that would need to be preserved between 'resets'.

> The checklists bring the aircraft back to a known state.

No, it doesn't, clearly. It provides a procedure that can be followed to put it to a known state, but its existence does not put it into a known state, with certainty. A reset puts it into a known state, with certainty. That known reset state probable wouldn't be useful, but can be set to be least-damaging, where a checklist can then be used to then put it into a "good" state.

My assumption is that many planes don't allow a reset to be trivial, since levers and whatnot are involved.

I also assume the FAA/military has done research into this and, probably, found that requiring a manual checklist resulted in stricter adherence to the checklist.

> My assumption is that many planes don't allow a reset to be trivial, since levers and whatnot are involved.

I think you are correct -- not everything is a software setting. There are physical switches and dials and other mechanical controls involved.

I'm surprised they don't do a full reset then set every checklist variable to an invalid state, in which the aircraft will not permit starting until all have been set by the flight crew.

This is the way. Like a computer-enforced Pointing and Calling.

I mean if you are able to do that, why to even have a checklist. I mean the computer must be able to complete the checklist, unless specified, no? Or is the checklist important because the pilots must know what they’re dealing with?

I can't say I have much of an idea of what goes on in a cockpit but presumably not everything is related to something a computer knows, or can change. Clean windscreens, functioning levers, coffee cup filled ;-)

Also having to poke the computer also helps check that the computer isn't obviously broken.

It takes a while (think like 10min+) to reboot these planes. Checkout "cold start 777" on YouTube [1].

There are a ton of computers (FADECs for engines, fuel management computers, FMS (flight management), PFC (flight computers), weight and balance computers... and much more). All of these have state. Which way is up for the gyros. Proper direction for the compasses. Proper location on Earth for the navigation system... etc. Basically, a 777 has the mother of all POST sequences, so frames in line operation are rarely restarted, for operational efficiency.

Reminds me of the navigation systems for some rockets (Atlas, IIRC), that require 24 hrs sitting level on the pad to fully initialize their starting ground state (super precise gyros). This ain't like restarting your internet connected juicer.

[1] https://www.youtube.com/watch?v=z6UCD0o0NCU

...unless you need to reboot to prevent the system from crashing inflight because of timer overflow https://arstechnica.com/information-technology/2015/05/boein...

It takes too long and would achieve little. Flight turnaround times are very tight. The process for updating software on aircraft is, understandably, tightly controlled and only takes place via physical access. Pilots wouldn't know how.

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