5 ms·

All flight controls on the A330 are fly-by-wire - they're connected via computers. The most critical surfaces have secondary, dumb controllers that can take ove

All flight controls on the A330 are fly-by-wire - they're connected via computers. The most critical surfaces have secondary, dumb controllers that can take over if the primary flight computers fail, but less critical systems may not be connected to those backup systems - it's expected that a triple fault of the primary flight computers should be very rare, and manual braking is available as a backup after all.

NovemberWhiskey 5y ago
Right. In this case we have a completely-unprecedented triple failure of the primary flight control system causing loss of auto-brake, spoilers and thrust reversers; a wet runway with less than expected braking action; a tailwind landing and still a happy outcome. Honestly defense-in-depth seems to be working OK here.
- gsnedders 5y ago
  And note that for all aircraft the landing distance is calculated _without_ thrust reversers or spoilers, and thus is based on braking performance alone. Some of the challenge here was the seconds spent at near landing speed without any braking being performed, as that'll eat up runway distance fast, following the auto brake failure prior to manual braking commencing.
  - azalemeth 5y ago
    It's also worth stating (for the OP) that thrust reversers are potentially really dangerous -- if they deploy in flight without being commanded to, the aircraft can -- or, more likely if the engine computer does not detect it and shut itself down, will become barely controllable, with previous fatal outcomes. [1] Two or more FCPCs failing is sufficient evidence that a "faecal fan incident may be occurring" that the risk of deploying them is just not worth it, especially as (pointed out by this parent above) they are effectively optional equipment and the FAA requires you to expect them to be inop to be safe. What they do save is fuel and time -- taxi time to the terminal, permit the use of high-speed runway turnoffs, etc. [1] https://en.wikipedia.org/wiki/Lauda_Air_Flight_004 https://en.wikipedia.org/wiki/Lauda_Air_Flight_004
    - birdyrooster 5y ago
      (An aside) Bruh the ppl in Thailand looted the wreck, how sad is that. What kind of shit person does such a thing?
      - birdyrooster 5y ago
        Hell yeah downvote me for calling out despicable behavior. These are the best kinds of downvotes.
        birdyrooster 5y ago
        Like if this happened to a flight in Florida, we would be making Florida Man memes and shit. It's clear there is a double standard here.
- redis_mlc 5y ago
  > Honestly defense-in-depth seems to be working OK here. No. Given that once a computer failure happens (p=1.0), then you analyze what the recovery procedures are from that point. It sounds like Airbus is unsafe at that point. This scenario illuminates why Boeing and Airbus have different automation philosophies. Source: commercially-rated pilot.
- digikata 5y ago
  Yes, it worked because there as a direct controller to fall back to. But worryingly because two things, it wasn’t a triple failure of the redundant flight computers, is seems to point to a singular failure of the monitoring logic. The other thing is that the report notes that the aircraft came perilously close to a disaster because it calls out other specific factors could have easily eaten up runway margin leading to a disaster.
- deleted 5y ago
  [deleted]

NovemberWhiskey 5y ago

Right. In this case we have a completely-unprecedented triple failure of the primary flight control system causing loss of auto-brake, spoilers and thrust reversers; a wet runway with less than expected braking action; a tailwind landing and still a happy outcome. Honestly defense-in-depth seems to be working OK here.

gsnedders 5y ago
And note that for all aircraft the landing distance is calculated _without_ thrust reversers or spoilers, and thus is based on braking performance alone. Some of the challenge here was the seconds spent at near landing speed without any braking being performed, as that'll eat up runway distance fast, following the auto brake failure prior to manual braking commencing.
- azalemeth 5y ago
  It's also worth stating (for the OP) that thrust reversers are potentially really dangerous -- if they deploy in flight without being commanded to, the aircraft can -- or, more likely if the engine computer does not detect it and shut itself down, will become barely controllable, with previous fatal outcomes. [1] Two or more FCPCs failing is sufficient evidence that a "faecal fan incident may be occurring" that the risk of deploying them is just not worth it, especially as (pointed out by this parent above) they are effectively optional equipment and the FAA requires you to expect them to be inop to be safe. What they do save is fuel and time -- taxi time to the terminal, permit the use of high-speed runway turnoffs, etc. [1] https://en.wikipedia.org/wiki/Lauda_Air_Flight_004 https://en.wikipedia.org/wiki/Lauda_Air_Flight_004
  - birdyrooster 5y ago
    (An aside) Bruh the ppl in Thailand looted the wreck, how sad is that. What kind of shit person does such a thing?
    - birdyrooster 5y ago
      Hell yeah downvote me for calling out despicable behavior. These are the best kinds of downvotes.
      - birdyrooster 5y ago
        Like if this happened to a flight in Florida, we would be making Florida Man memes and shit. It's clear there is a double standard here.
redis_mlc 5y ago
> Honestly defense-in-depth seems to be working OK here. No. Given that once a computer failure happens (p=1.0), then you analyze what the recovery procedures are from that point. It sounds like Airbus is unsafe at that point. This scenario illuminates why Boeing and Airbus have different automation philosophies. Source: commercially-rated pilot.
digikata 5y ago
Yes, it worked because there as a direct controller to fall back to. But worryingly because two things, it wasn’t a triple failure of the redundant flight computers, is seems to point to a singular failure of the monitoring logic. The other thing is that the report notes that the aircraft came perilously close to a disaster because it calls out other specific factors could have easily eaten up runway margin leading to a disaster.
deleted 5y ago
[deleted]