Comment by rich_sasha
1 year ago
Scary as it is, is there any reason for a passenger jet to have uptime if more than, say, 24hrs? Wouldn't you just switch it off and on again between every flight, regardless?
If this issue was in a car, we would never know as no one keeps their car running for 50 days straight.
Overnight, planes tend to be plugged in to ground power, to ventilate, keep the batteries charged, for the cleaning crews, etc. Most get rebooted once in a while, but it's always possible one won't be, hence the directive to be certain.
This particular problem has been known for years (the article is from 2020).
Unfortunately, an aircraft has no “reboot”. It is just a violent power cut. A lot of headache is introduced in non-critical aircraft software because there is no “graceful shutdown” or long power duration. Infact, certain hardware has an upper limit(much lower than a week) before which it needs one power cut(sometimes called power cycle) or it suffers from various buffer overflow, counter overflow and starts acting mysterious.
It's amazing that's legal. Like, why do we accept software that does this? It can be done in such a way that these things don't happen.Put another way, why aren't the companies involved being fined and sued out of business? Why aren't their managers facing criminal negligence charges? It's outrageous.
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> Unfortunately, an aircraft has no “reboot”. It is just a violent power cut.
That’s a reboot.
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This has to be a joke right ?
You're telling me Aerospace's "real engineering-level" is worse than something a sophomore can cook up ?
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>an aircraft has no “reboot”. It is just a violent power cut
Guess how I typically reboot things :)
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Many car's control units continue to run while the car is off. If you want to reboot your vehicle, you need to unplug the 12v battery for at least a minute.
On some cars (recent VWs in particular) when you plug the battery back in you need to twiddle some settings in the computer otherwise the charging circuit will fry the battery prematurely. We've gotten ahead of our skis with this nonsense, time to rein it in.
This issue is notorious for BMW cars. You have to notify the ECU each time you install a new battery.
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Rein. It’s about controlling a horse, not an entire nation.
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Some of these planes are constantly flying as long as they're not in maintenance. A plane not in the air is a plane the company bought that's not currently generating profit.
I’ll bet you the typical EV stays powered on 24/7 with reboots around OTA updates.
unsure what you mean here. most of the systems go to a sleep state in modern vehicles ev or not. the 12v battery keeps only certain ECU's up - think ECUs that control alarm, lock and unlock state and any communication with the mobile app via LTE... but the rest of the systems are OFF, you don't want an EV battery to hit 0% and 12V to also hit 0% - that would basically make it a brick from what I understand- because EV's have contactors which need to shut for the battery to be 'engaged' the 12V battery controls these contactors.
A car with an enormous rack of high capacity batteries able to accelerate an 8000 pound object to 60mph and sustain that for hundreds of miles generally doesn’t depend on the backup battery for literally anything. It has so much excess energy storage in the form of electricity in the primary batteries it generally doesn’t power down the onboard computers at all.
Indeed when you get close to exhausting the main battery rack it starts selectively shutting down everything. I’ve never personally let mine get to 0% ever - but for instance a Tesla is continuously on, and if you use sentry mode it’s not just on but the GPU is constantly doing classification of the environment to determine if someone is prowling your vehicle.
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Low voltage battery death in any EV essentially causes a brick. The only exception is some cars (I think Tesla does this?) keep their contactors closed all the time when the 12v is determined to be failing. It makes the drain at idle much higher, but then at least it can continue moving… as long as you don’t let the HV pack drain…
Very strange, because for me, an aircraft(medium) is never alive for more than 24h. A big one like 787 may be alive for up to 72h(assuming longer routes). 50 days for me would be a dream and a lot less headache but it is very expensive to keep an aircraft powered that long with ground power.
> it is very expensive to keep an aircraft powered that long with ground power.
Why do you say this?
I know someone on the north slope of Alaska. He does not turn his personal truck off all winter. This is even more typical for semi trucks and whatnot around there.
I think it's about the worst case scenario. You wouldn't want this to happen even rarely, especially when it can be solved by putting more time (and god forbid, money) into R&D.
Airlines will run the aircraft as long as possible. As another commenter mentioned, if an aircraft isn't in flight, it's in maintenance. All of these times it's on.
It's another thing on a checklist that can go wrong.