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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

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?

RealityVoid 10mo ago
Because the problem isn't just this. It's that the flight controller did not properly decide what to do when the data spiked because of this issue as well.
Havoc 10mo ago
> Why would they be using flight computers from before 2002? Guessing that using previously certified stuff is an advantage
LiamPowell 10mo ago
> 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.
- K0balt 10mo ago
  That’s just wild to think about. We should all strive to build solutions that plague our descendants with their persistent utility.
  - hylaride 10mo ago
    From a pure safety point of view, it's easier to deal with older, but well-understood products, only updating them if it's an actual safety issue. The alternative is having to deal with many generations of tech, as well as permutations with other components, that could get infinitely complicated. On top of that, it's extremely time consuming and expensive to certify new components. There's a reason the airlines and manufacturers hem and haw about new models until the economics overwhelmingly make it worthwhile, and even then it can still be a shitshow. The MCAS issue is case in point of how introducing new tech can cause unexpected issues (made worse by Boeing's internal culture). The 787 dreamliner is also a good example of how hard it is. By all accounts is a success, but it had some serious teething problems and still has some concerns about the long term wear and tear of the composite materials (though a lot of it's problems wasn't necessarily the application of new tech, but Boeing's simultaneous desire to overcomplicate the manufacturing pipeline via outsourcing and spreading out manufacturing).
4ndrewl 10mo ago
The neo is not brand new - it's an incremental update to the 320. neo refers to New Engine Option
- rkomorn 10mo ago
  They wrote "some of which are basically brand new", which is technically correct. They didn't say the design was brand new.
t0mas88 10mo ago
> Why would they be using flight computers from before 2002? Because getting a new one certified is extremely expensive. And designing an aircraft with a new type certificate is unpopular with the airlines. Since pilots are locked into a single type at a time, a mixed fleet is less efficient. Having a pilot switch type is very expensive, in the 50-100k per pilot range. And it comes with operational restrictions, you can't pair a newly trained (on type) captain with a newly trained first officer, so you need to manage all of this.
- Reason077 10mo ago
  I think you're confusing a type certificate (certifying the airworthiness of the aircraft type) with a type rating, which certifies the pilot is qualified to operate that type. Significant internal hardware changes might indeed require re-certification, but it generally wouldn't mean that pilots need to re-qualify or get a new type rating.
  - t0mas88 10mo ago
    No I meant designing a new aircraft with a new type certificate instead of creating the A320neo generation on the same type certificate. The parent comment wondered why Airbus would keep the old computers around, I tried to explain why they keep a lot of things the same and only incrementally add variants. Adding a variant allows them to be flown with the same type rating or with only differences training (that's what EASA calls it, not sure about the US term) which is much less costly.
    - darkwater 10mo ago
      Asking from ignorance: shouldn't the computer design be an implementation detail to the captain, while the interface used by who pilots stays the same for that type of airplane? I understand physical changes in the design need a retraining but the computer?
      - t0mas88 10mo ago
        Ideally you would not change the computer at all so your type certificate doesn't change. If you have to (or for commercial reasons really want to) make a change you would try very hard to keep that the same type certificate or at most a variant of the same type certificate. If you can do that then it will be flown with the same type rating and you avoid all the crew training cost issues. But to do that you'll still have to prove that the changes don't change any of the aircraft characteristics. And that's not just the normal handling but also any failure modes. Which is an expensive thing to do, so Airbus would normally not do this unless there is a strong reason to do it. The crew is also trained on a lot of knowledge about the systems behind the interface, so they can figure out what might be wrong in case of problems. That doesn't include the software architecture itself but it does include a lot of information on how redundancy between the systems work and what happens in case one system output is invalid. For example how the fail over logic works in case of a flight control computer failure, or how it responds to loosing certain inputs. And how that affects automation capabilities, like: no autoland when X fails, no autopilot and degradation to alternate contol law when Y fails, further degradation if X and Z fail at the same time. Sometimes also per "side", not all computers are connected to all sensors. The computer change can't change any of that without requiring retraining.
RealityVoid 10mo ago
The issue detailed in the linked report details why the spike happened in the first place on the ADIRU (produced by Northrop Gruman). The recalled controller is the ELAC that comes from Thales. The problem chain was that despite the ADIRU spiking up, the ELAC should not have taken the reactions it took. So they are fixing it in the ELAC.
p_l 10mo ago
For the same reasons that Honeywell is building new devices with AMD 29050 CPUs today[1] - by sticking with the same CPU ISA, they can avoid recertifying portion of the software stack. [1] Honeywell actually bought full license et al from AMD and operates a fabless team that ensures they have stock and if necessary updates the chip.

RealityVoid 10mo ago

Because the problem isn't just this. It's that the flight controller did not properly decide what to do when the data spiked because of this issue as well.

Havoc 10mo ago

> Why would they be using flight computers from before 2002? Guessing that using previously certified stuff is an advantage

LiamPowell 10mo ago

> 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.

K0balt 10mo ago
That’s just wild to think about. We should all strive to build solutions that plague our descendants with their persistent utility.
- hylaride 10mo ago
  From a pure safety point of view, it's easier to deal with older, but well-understood products, only updating them if it's an actual safety issue. The alternative is having to deal with many generations of tech, as well as permutations with other components, that could get infinitely complicated. On top of that, it's extremely time consuming and expensive to certify new components. There's a reason the airlines and manufacturers hem and haw about new models until the economics overwhelmingly make it worthwhile, and even then it can still be a shitshow. The MCAS issue is case in point of how introducing new tech can cause unexpected issues (made worse by Boeing's internal culture). The 787 dreamliner is also a good example of how hard it is. By all accounts is a success, but it had some serious teething problems and still has some concerns about the long term wear and tear of the composite materials (though a lot of it's problems wasn't necessarily the application of new tech, but Boeing's simultaneous desire to overcomplicate the manufacturing pipeline via outsourcing and spreading out manufacturing).

4ndrewl 10mo ago

The neo is not brand new - it's an incremental update to the 320. neo refers to New Engine Option

rkomorn 10mo ago
They wrote "some of which are basically brand new", which is technically correct. They didn't say the design was brand new.

t0mas88 10mo ago

> Why would they be using flight computers from before 2002? Because getting a new one certified is extremely expensive. And designing an aircraft with a new type certificate is unpopular with the airlines. Since pilots are locked into a single type at a time, a mixed fleet is less efficient. Having a pilot switch type is very expensive, in the 50-100k per pilot range. And it comes with operational restrictions, you can't pair a newly trained (on type) captain with a newly trained first officer, so you need to manage all of this.

Reason077 10mo ago
I think you're confusing a type certificate (certifying the airworthiness of the aircraft type) with a type rating, which certifies the pilot is qualified to operate that type. Significant internal hardware changes might indeed require re-certification, but it generally wouldn't mean that pilots need to re-qualify or get a new type rating.
- t0mas88 10mo ago
  No I meant designing a new aircraft with a new type certificate instead of creating the A320neo generation on the same type certificate. The parent comment wondered why Airbus would keep the old computers around, I tried to explain why they keep a lot of things the same and only incrementally add variants. Adding a variant allows them to be flown with the same type rating or with only differences training (that's what EASA calls it, not sure about the US term) which is much less costly.
  - darkwater 10mo ago
    Asking from ignorance: shouldn't the computer design be an implementation detail to the captain, while the interface used by who pilots stays the same for that type of airplane? I understand physical changes in the design need a retraining but the computer?
    - t0mas88 10mo ago
      Ideally you would not change the computer at all so your type certificate doesn't change. If you have to (or for commercial reasons really want to) make a change you would try very hard to keep that the same type certificate or at most a variant of the same type certificate. If you can do that then it will be flown with the same type rating and you avoid all the crew training cost issues. But to do that you'll still have to prove that the changes don't change any of the aircraft characteristics. And that's not just the normal handling but also any failure modes. Which is an expensive thing to do, so Airbus would normally not do this unless there is a strong reason to do it. The crew is also trained on a lot of knowledge about the systems behind the interface, so they can figure out what might be wrong in case of problems. That doesn't include the software architecture itself but it does include a lot of information on how redundancy between the systems work and what happens in case one system output is invalid. For example how the fail over logic works in case of a flight control computer failure, or how it responds to loosing certain inputs. And how that affects automation capabilities, like: no autoland when X fails, no autopilot and degradation to alternate contol law when Y fails, further degradation if X and Z fail at the same time. Sometimes also per "side", not all computers are connected to all sensors. The computer change can't change any of that without requiring retraining.

RealityVoid 10mo ago

The issue detailed in the linked report details why the spike happened in the first place on the ADIRU (produced by Northrop Gruman). The recalled controller is the ELAC that comes from Thales. The problem chain was that despite the ADIRU spiking up, the ELAC should not have taken the reactions it took. So they are fixing it in the ELAC.

p_l 10mo ago

For the same reasons that Honeywell is building new devices with AMD 29050 CPUs today[1] - by sticking with the same CPU ISA, they can avoid recertifying portion of the software stack. [1] Honeywell actually bought full license et al from AMD and operates a fabless team that ensures they have stock and if necessary updates the chip.