Bit flips: How cosmic rays grounded a fleet of aircraft

Good part selection and different EMI environment meant the calculated risks from not having ECC were considered too low to care and the idea that they might have to deal with radiation outside of flying near nuclear explosion arrived after the specific devices got designed.

But for the 2008 incident I read and linked the report, that was what happened. The ADIRU unit did probably get a SEU event and that should have been mitigated by the design of the ELAC unit. The ELAC unit failed to mitigate it so that's the part that they probaby fixed.

https://www.atsb.gov.au/sites/default/files/media/3532398/ao...

My reaction was initially that it was a cop out, but looking a bit in the report and thinking things through, I think that, yes, it's most likely a bit flip.

The plane is fundamentally unstable because of the huge engines (which they have to improve fuel efficiency).

The only way to correct that is software with an angle of attack sensor.

They only installed one sensor though.

Does that sound like a software error or a fundamental physical design flaw?

It did not. The article itself acknowledged that there is certainly reason to consider it a possibility, predicated on the fact that the people that make the thing stated as such and that experts in the field agree it's also a risk in general, but wasn't particularly high that day.

Average activity is not no activity. Average risk is not No risk.

And even if it wasn't the issue in that instance, it's not hard to reason why it's worth hardening against such a possibility in the absence of any other explanation given just days later "sensors mounted on UK weather balloons at 40,000ft (12km) measured one of the largest radiation events to hit Earth in roughly two decades."

Airbus didn't ground these plains because there was "No reason to believe" a known proven and observed phenomenon might have been the culprit and/or that it is on the level with something we as yet have no proof of to be generous in characterizing your comparing it to aliens.

So shielding is not a solution that can be applied in a vehicle. You need something like an underground bunker to be sure that no cosmic radiation can penetrate it.

The only reason that makes rare the events caused by cosmic radiation is that if those particles can pass through shields that means that in most cases they will also pass through the electronic devices without being absorbed and causing malfunction.

    try {
        do_action()
    } catch (BitFlipError e) {
        logger.critical("Shouldn't get here")
    }

  int cosmic_ray = 0
  if (bool(cosmic_ray)) {
     throw cosmicRayException()
  }

Despite that, most of the existing planes have an older model, which has not been upgraded.

I take my analysis on this back, it was true only for the other incident. I can't edit my answers anymore now. Not sure what is going on with this failure, would love to read a detailed analysis report as the other one I went through.