[UpThere]

The US Federal Aviation Administration has ordered Boeing 787 operators to switch their aircraft off and on every 51 days to prevent what it called "several potentially catastrophic failure scenarios" – including the crashing of onboard network switches.
...
According to the directive itself, if the aircraft is powered on for more than 51 days this can lead to "display of misleading data" to the pilots, with that data including airspeed, attitude, altitude and engine operating indications. On top of all that, the stall warning horn and overspeed horn also stop working. - The Register

As someone who earns a living from writing computer software, I've long doubted the wisdom of putting my life in the hands of a computer programmer! All non-trivial code contains bugs - as crashes of the 737 Max and driverless cars have demonstrated - but dreams of saving money and cutting out human failures will no doubt keep driving the development of automation.

[Morten]

If true (and the Register are normally pretty good) that is hilarious.

Not really.

Reminds me of an old joke:
Windows 3.11 had an internal counter which if it went out of limit, which would happen after 4 days or so, would cause the system to freeze. Luckily, it was never seen in practice since Windows 3.11 normally froze every 2 hours or so for a whole host of different reasons anyway...

[PaulB]

If true (and the Register are normally pretty good) that is hilarious.

The Reg article does cite the AD

https://ad.easa.europa.eu/ad/US-2020-06-14

[lobstaboy]

Why 51 days exactly?

Is that a computer 'thing'?

[Morten]

I didn't spot the link - nice. And it's not dated yesterday. Wow. We live in exceptional times...

Maybe 51 days is 2^32 seconds or something (clearly not. but it does smell of an out of bounds issue?)

Variables going out of bounds caused the maiden flight failure of Ariane 5 - and no doubt a whole host of other disasters.
For those with spare time:
Video:

Report: http://sunnyday.mit.edu/nasa-class/Ariane5-report.html

[Paul_Sengupta]

That's curious, I remember seeing this months ago. Maybe the recent announcement is a particular AD or a revision or something.

Edit: Months in "Paul time". It was 2015.

https://www.engadget.com/2015-05-01-boeing-787-dreamliner-software-bug.html

I guess 248 days has been revised to 51 days.

Ah, I've now actually clicked on the article and it says:

"A previous software bug forced airlines to power down their 787s every 248 days for fear that electrical generators could shut down in flight."

Also:

"Airbus suffers from similar issues with its A350, with a relatively recent but since-patched bug forcing power cycles every 149 hours."

[Lockhaven]

We regularly do a CTRL / ALT delete to reset our aircraft when it dreams up a fault that cannot be cleared, this usually also requires the batteries to be disconnected for a few minutes then reconnect and power up.

[Jim Jones]

[list=][/list]

We regularly do a CTRL / ALT delete to reset our aircraft when it dreams up a fault that cannot be cleared, this usually also requires the batteries to be disconnected for a few minutes then reconnect and power up.

Ditto my car, my iPad, my phone, my laptop, my router, my Virgin pvr, my printer, ...

[malcolmfrost]

don't forget my car! (Tesla 3)

[bencoder]

Maybe 51 days is 2^32 seconds or something (clearly not. but it does smell of an out of bounds issue?)

It's very close to 2^32 ms. But that would overflow around day 50, rather than 51, so it's quite odd!

[allout]

The EMB145's equivalent of CTRL ALT DELETE never failed, in my experience.
(ground only, obvs)
Far more challenging was finding soothing words for the passengers before the whole machine went dark and silent.

[Josh]

There is a list of approved “turn it on and off again” in the Airbus QRH. Lots on the ground. Not so many in flight. Pretty much all involve circuit breaker kerplunk of some kind.

Dont try ground only resets in flight

A lot of engineers are also really not looking forward to booting up a bunch of aircraft left idle for months in the not too distant future!

[Human Factor]

The best way to repower an Airbus was “battery on, ground power on, walk away for ten minutes”.

[BobD]

Re the Thread Headline. Shades of the IT Crowd TV sitcom. I remember how much I laughed the first time I heard Roy utter those immortal, true words, having worked in IT for over 30 years.

[Josh]

The IT crowd was pure comic genius. Who could forget street countdown?