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from the have-you-tried-turning-it-off-and-back-on-again? dept.
Submitted via IRC for Bytram
Airbus A350 software bug forces airlines to turn planes off and on every 149 hours
Some models of Airbus A350 airliners still need to be hard rebooted after exactly 149 hours, despite warnings from the EU Aviation Safety Agency (EASA) first issued two years ago.
In a mandatory airworthiness directive (AD) reissued earlier this week, EASA urged operators to turn their A350s off and on again to prevent "partial or total loss of some avionics systems or functions".
The revised AD, effective from tomorrow (26 July), exempts only those new A350-941s which have had modified software pre-loaded on the production line. For all other A350-941s, operators need to completely power the airliner down before it reaches 149 hours of continuous power-on time.
Concerningly, the original 2017 AD was brought about by "in-service events where a loss of communication occurred between some avionics systems and avionics network" (sic). The impact of the failures ranged from "redundancy loss" to "complete loss on a specific function hosted on common remote data concentrator and core processing input/output modules".
In layman's English, this means that prior to 2017, at least some A350s flying passengers were suffering unexplained failures of potentially flight-critical digital systems.
Not a power of two. I wonder why 149 hours?
(Score: 2) by driverless on Saturday July 27 2019, @08:51AM
Oh, another thing, we typically found these odd problems in low-level components that we didn't control. The software itself was written extremely carefully - think something like MISRA on steroids, with some parts accompanied by formal PROMELA/SPIN proofs - but then you'd get some low-level transceiver with a tiny built-in state machine that the model saw as a black box which would end up in an unexpected state under some circumstances. So it was the low-level gunk you didn't directly control that ended up biting you.
Point is, it may not be something that Airbus has any direct control over that's causing this.