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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

#101

Post by Normal_gaussian »

RealityVoid wrote: post #96
Liftyee wrote: post #93

Earlier quoted context omitted.

What does EDAC mean here? I wasn't able to find a definition. My guess is "error detection and correction"? Difference between it and ECC?

That was my initial confusion as well. It means exactly what you guessed, "Error detection and correction". The term is also spelled out in the report. I asked Claude about it (caveat emptor) and it said EDAC is the correct name for the circuitry and implementation itself whereas ECC is the algorithm. Gemini said that EDAC is the general technique and ECC is one implementation variant. So, at this point, I'm not sure…

Large portions of this comment provides zero to negative value. You've quoted two LLMs and couched it in "caveat emptor" and "so I'm not sure". The rest of your comment has then mused over this data you do not trust using generalities ("my profession" are you a JS S/W eng? A chip design specialist at ARM? A security researcher?).

All of the value of your comment comes from the first sentence and the last two.

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

#102

Post by K0balt »

RealityVoid wrote: post #98
JorgeGT wrote: post #88

Earlier quoted context omitted.

I don't know about the A320 but this was certainly the model for the Eurofighter. One of my university professors was in one of the teams, they were given the specs and not allowed to communicate with the other teams in any way during the hw and sw development.

> they were given the specs and not allowed to communicate with the other teams in any way during the hw and sw development. Jeez, it would drive me _up the wall_. Let's say I could somewhat justify the security concerns, but this seems like it severely hampers the ability to design the system. And it seems like a safety concern.

The idea was to build three completely different systems to produce the same data, so that an error or problem in one could not be reasonably replicated in the others. In a case such as this, even ideas about algorithms could result in undesirable similarities that could end up propagating an attack surface, a logic error, or a hardware weakness or vulnerability. The desired result is that the teas solve the problem separately using distinct approaches and resources.

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

#103

Post by lambdaone »

RealityVoid wrote: post #98
JorgeGT wrote: post #88

Earlier quoted context omitted.

I don't know about the A320 but this was certainly the model for the Eurofighter. One of my university professors was in one of the teams, they were given the specs and not allowed to communicate with the other teams in any way during the hw and sw development.

> they were given the specs and not allowed to communicate with the other teams in any way during the hw and sw development. Jeez, it would drive me _up the wall_. Let's say I could somewhat justify the security concerns, but this seems like it severely hampers the ability to design the system. And it seems like a safety concern.

What you are trying to minimize here is the error rate of the composite system, not the error rate of the individual modules. You take it as a given that all the teams are doing their human best to eliminate mistakes from their design. The idea of this is to make it likely that the mistakes that remain are different mistakes from those made by the other teams.

Providing errors are independent, it's better to have three subsystems with 99% reliability in a voting arrangement than one system with 99.9% reliability.

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

#104

Post by K0balt »

Liftyee wrote: post #93
RealityVoid wrote: post #46

Earlier quoted context omitted.

See my other comments in the other threads. This does not have EDAC. I was as surprised as you but it doesn't seems to be an MCU but a composition of several distinct chips. That flight computer was designed in the 90's and updated in 2002 with a new hw variant that does have edac. So yes, for this kind of thing, I can buy that a bit flip happened. You can see much more data in the report: https://www.atsb.gov.au/sit…

What does EDAC mean here? I wasn't able to find a definition. My guess is "error detection and correction"? Difference between it and ECC?

EDAC is the concept, ECC is a family of algorithmic solutions in the service of the concept. Specific implementations of ECC are the engineering solution that implement the specific form of ECC in specific devices at the hardware or software level.

It’s confusing because EDAC and ECC seem to mean the same thing, but ECC is a term primarily used in memory integrity, where EDAC is a system level concept.

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

#105

Post by upcoming-sesame »

f1shy wrote: post #53
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.

I would personally not want to seat in those planes in those 2 months.

nothing worse than rushing a fix in production - only to find out the fix has caused more damage than the original bug

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

#106

Post by willis936 »

jayanmn wrote: post #15
addaon wrote: post #7

I’d really, really like to know what microcontroller family this was found on. Assuming that this is a safety processor (lockstep, ECC, etc) it suggests that ECC was insufficient for the level of bit flips they’re seeing — and if the concern is data corruption, not unintended restart, it means it’s enough flips in one word to be undetectable. The environment they’re operating in isn’t that different from everyone els…

I am worried about a software fix for what looks like hardware problem.

It's a system problem. The system is being fixed.

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

#107

Post by K0balt »

LiamPowell wrote: post #62
Reason077 wrote: post #56

Earlier quoted context omitted.

The recalled aircraft include the latest A320neo model, some of which are basically brand new. Why would they be using flight computers from before 2002? Why is an old report from 2008, relating to a completely different aircraft type (A330), relevant to the A320 issue today?

> Why would they be using flight computers from before 2002? Why would you assume they're not? I don't know about aircraft specifically, but there's plenty of hardware that uses components older than that. Microchip still makes 8051 clones 45 years after the 8051 was released.

That’s just wild to think about. We should all strive to build solutions that plague our descendants with their persistent utility.

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

#108

Post by [deleted] »

LadyCailin wrote: post #78
nickdothutton wrote: post #76

I’d just like to point out that if you are in the computing industry long enough, you will get to see a few such incidents under different circumstances, not only in industries like aerospace. Mostly things like ECC save your a*, sometimes your software will be able to recognise a temporary spurious reading and disregard it because you had enough alternative checking logic, or in the case of realtime and safety criti…

We noticed this in our logs once! We service a huge amount of traffic, and as part of that, we log what is effectively an enum. We did a summarization of this field once, and noticed that there were a couple of “impossible” values being logged. One of my coworkers realized that the string that actually got logged was exactly one bit off from a valid string, and we came to the conclusion that we were probably seeing c…

[deleted]

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

#109

Post by K0balt »

CrossVR wrote: post #45
vel0city wrote: post #29

Earlier quoted context omitted.

I'm reminded of the Apollo moon landing where the computer was rapidly rebooting and being in an OK-ish state to continue to be useful almost immediately

It wasn't rebooting, it ran out of memory and started aborting lower priority tasks. It was a excellent example of robust programming in the face of unexpected usage scenarios.

Fail safe/fail soft

I still design this into many of the things I work on, especially if I’m working close to the metal on controller systems. At some point it becomes ridiculous / impossible but I’m often thinking about how a system would handle memory corruption, bit flips, invalid sensor data, etc. These days, somebody should design a triple redundant microcontroller that runs quorum on the gpio at the hardware level. It could be a 0.30 part instead of 0.10 one, but I would specify it just about everywhere. Add $3 to BOM cost to categorically eliminate an entire class of failure would be ramrodded by legal into just about every medical device, PLC, critical automotive system, etc one would think. Seems like a good gambit for a riscV startup, but what do I know.

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

#110

Post by probably_wrong »

kijin wrote: post #42
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.

I imagine it could help with Airbus marketing. "We take proactive measures, whereas our competitor only takes action after multiple fatal crashes!"

I know someone who is stranded in another continent thanks to this. Trust me, all the understanding I could have as a technical user has been offset by the MASSIVE pain in the ass that is rebooking an international flight. And non-technical users have heard "the plane will not travel because it requires a software update", which does not inspire confidence.

As far as I'm concerned it has not helped with their marketing.

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