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Airbus A320 – intense solar radiation may corrupt data critical for flight

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Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#111

Post by julik »

foldr wrote: post #82
themerone wrote: post #26

Earlier quoted context omitted.

Gracefully handling hardware faults is a software problem. The Air France Flight 447 crash was the result of bad software and bad hardware.

Crashes caused by pilots failing to execute proper stall recovery procedures are surprisingly common, and similar accidents have happened before in aircraft with traditional control schemes, so I’m skeptical that there are any hardware changes that would have made much difference. The official report doesn’t identify the hardware or software as significant factors. The moment to avoid the accident was probably the ve…

True. I would say, however, that every "concept" of airliner flight deck has its own gimmicks that can kill. The Airbus "dual input" is such a gimmick. Even though there was, for example, an AF accident with a 777 where there was hardware linkage between yokes and the two pilots were fighting... each other. Physically.

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#112

Post by julik »

jakub_g wrote: post #87

From newspaper reporting on this, they are rolling back a software update. I wonder what was the original cause or the update? How often are flight computers software updated and why?

This ELAC version is 100-something, and the A320 first flew around 1988. Why the updates - for example, there are updates to flight control law transitions, like after 1991 where the aircraft would limit flight control inputs during landing, thinking it would be preventing a stall - because it would not go into the flare law appropriately. See https://en.wikipedia.org/wiki/Iberia_Flight_1456

The cause could have also been an extra check introduced in one of the routines - which backfired in this particular failure scenario.

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#113

Post by nolist_policy »

pyb wrote: post #48

The aerospace industry has had countermeasures in place against bit-flips for a long time, oftentimes thanks to redudancy Airbus/Thales's fix in this case appears to add more error checking, and to restart the misbehaving component. https://bea.aero/fileadmin/user_upload/BEA2024-0404-BEA2025-... ("une supervision interne du composant à l’origine de la défaillance ; - un mécanisme de redémarrage automatique de ce comp…

The linked document is not related to this incident.

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#114

Post by julik »

jfoster wrote: post #47
icegreentea2 wrote: post #28

Earlier quoted context omitted.

The grounding is for 6000 of 11000 A320 series. I believe it's some combination of software and hardware configuration that is at risk.

Thank you; that makes sense. I had the impression it was the entire fleet.

It depends on whether the ELAC is an LRU (line-replaceable unit, i.e. a box with ports that can be swapped at an airport) and whether a software update can be uploaded into a unit that is installed (not all aircraft have a "firmware update via cable or floppy", so to speak)

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#115

Post by yread »

supernova87a wrote: post #86

I wonder how the incident was diagnosed? Does the FDR record low level errors that might've contributed to this? I thought that it only recorded certain input parameters and high-level flight metrics but I'm no expert. If a radiation event caused some bit-flip, how would you realize that's what triggered an error? Or maybe the FDR does record when certain things go wrong? I'm thinking like, voting errors of the main…

From a comment on avherald:

"Had the same problem with low power CMOS 3 transistor memory cells used in implantable defibrillators in the 1990s. Needed software detection and correction upgrade for implanted devices, and radiation hardening for new devices. Issue was confirmed to be caused by solar radiation by flying devices between Sydney and Buenos Aires over the south pole multiple times, accumulating a statistically significant different error rate to control sample in Sydney."

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#116

Post by Esophagus4 »

Bud wrote: post #44
joelthelion wrote: post #34

Do they really need to ground the entire fleet for that? One incident for ten thousand planes in the air for years. I'd think that giving airlines two months to fix it would be sufficient.

From their viewpoint, you have to think about what happens if, after they became aware of this vulnerability, there was then a crash because they weren't prompt and aggressive enough in addressing it. That's the kind of thing that ruins your entire company forever.

Yep - Boeing is still dealing with it years later.

(As they should - I’m still very mad at them.)

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#117

Post by f1shy »

amelius wrote: post #84
f1shy wrote: post #50

Earlier quoted context omitted.

And bad pilot training, if I recall correctly.

I suppose because they were not instructed to work around the software and hardware flaws.

No. The behavior was wrong, no matter what you are flying. Same problem with proper training would have result in a simple report.

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#118

Post by f1shy »

janeric1 wrote: post #90
amelius wrote: post #84

Earlier quoted context omitted.

I suppose because they were not instructed to work around the software and hardware flaws.

Because they kept pitching up in a stall

And two pilots were trying to fly the plane without talking to each other. One learned “if something happens just pull back, this plane cannot stall”. No pilot learned to say “my plane” when flying. Way too many errors.

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#119

Post by V__ »

rkagerer wrote: post #52
anonymousiam wrote: post #43

Earlier quoted context omitted.

proper SEU mitigation goes far beyond ECC. Satellites fly higher than the A320, and they (at least the ones I know about) use Triple Modular Redundancy: https://en.wikipedia.org/wiki/Triple_modular_redundancy https://en.wikipedia.org/wiki/Single-event_upset For manned spaceflight, NASA ups N from 3 to 5. Other mitigations include completely disabling all CPU caches (with a big performance hit), and continuously refre…

In redundant systems like these, how do you avoid the voting circuit becoming a single point of failure? Eg. I could understand if each subsystem had its own actuators and they were designed so any 3 could aerodynamically override the other 2, but I don't think that's how it works in practice.

Can't this be solved by having a "high refresh-rate"? Even if the voting circuit gets hit, if it updates 60 times a second it won't really affect any mechanical parts since the next signal will quickly override the error?

Re: Airbus A320 – intense solar radiation may corrupt data critical for flight

#120

Post by [deleted] »

julik wrote: post #111
foldr wrote: post #82

Earlier quoted context omitted.

Crashes caused by pilots failing to execute proper stall recovery procedures are surprisingly common, and similar accidents have happened before in aircraft with traditional control schemes, so I’m skeptical that there are any hardware changes that would have made much difference. The official report doesn’t identify the hardware or software as significant factors. The moment to avoid the accident was probably the ve…

True. I would say, however, that every "concept" of airliner flight deck has its own gimmicks that can kill. The Airbus "dual input" is such a gimmick. Even though there was, for example, an AF accident with a 777 where there was hardware linkage between yokes and the two pilots were fighting... each other. Physically.

[deleted]
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