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FWIW, the near-crash in the simulator was apparently not directly related to MCAS, but occurred when Boeing "simulated what would happen if gamma rays from spac

by danso 7y ago

FWIW, the near-crash in the simulator was apparently not directly related to MCAS, but occurred when Boeing "simulated what would happen if gamma rays from space scrambled data in the plane’s flight-control computers." > In one scenario, the plane aggressively dove in a way that mimicked what happened in the crashes on the grounded jetliner, the people said. While such a failure had never occurred in the 737’s history, it was at least theoretically possible. > Because at least one of the pilots who flew the scenario in a simulator found it difficult to respond in time to maintain control of the plane, it needed to be fixed, according to two people familiar with the results. However, the next sentence seems to belie the implication that this was just an edge case: > The answer was to modernize what was a relatively antiquated design on the 737. So, of all the things that caused Boeing/FAA to realize and the accept the 737 needed to modernize its decades-old design, it was a simulated edge case involving "gamma rays from space"? Hate to be overly cynical, but that sounds like the kind of CYA thing you'd say when you don't want to admit it you made a huge mistake by deferring modernization in the first place, of which the MCAS concept was a major and disastrous symptom.

branchan 7y ago
I find it hard to believe that they are completely re-designing the avionics/flight computers because of this gamma ray incident. There must be another reason. If it's seriously the main concern, wouldn't it be much easier to just encase the computer in several inches of lead shielding?
Tomte 7y ago
> a simulated edge case involving "gamma rays from space"? Soft-errors are a prime concern when designing safety-critical systems, both in hardware and in software. It's not some outlandish edge case. Incidentally, while soft-errors in an airplane are probably primarily particles from space, on the ground we're still sometimes talking about it, but in reality it's mostly chip packages that are low radioactive and emitting a alpha particle or so.
- danso 7y ago
  I don't disagree that this is an important thing to test for. I question why this is the reported explanation for why Boeing now decided that the computer systems needed an extensive overhaul. Ostensibly, "gamma rays from space" affecting flight control computers would be an issue that affected Boeing's planes long before MCAS. But it's not the gamma rays that are the reason for the systems redesign, it's the fact that "at least one of the pilots who flew the scenario in a simulator found it difficult to respond in time to maintain control of the plane". Boeing's assumption that pilots could respond quickly enough to a loss of control in the cockpit was an underlying motivation for designing MCAS with inadequate safety measures.
  - salawat 7y ago
    Also, there is a regulation that requires no design have a single point of failure capable of resulting in a catastrophic outcome. That's why they have to rearchitect the system. If those bit-flips happened to the Flight Computer in command, they could lose the plane. Therefore, redundancy must be built in. It wasn't originally evaluated as posing a catastrophic outcome in the safety analysis, which is why no one paid it any mind.
Havoc 7y ago
>at least one of the pilots who flew the scenario in a simulator found it difficult to respond And I'm guessing their not using pilots of average skill here...
- Operyl 7y ago
  According to [0] the FAA was looking for numerous candidates to get a good range of experience, so I would think that you might’ve had at least a few average pilots. [0]: https://www.reuters.com/article/us-ethiopia-airplane-faa-boeing/faa-says-it-will-invite-global-boeing-737-max-pilots-to-simulator-tests-idUSKCN1VC28R https://www.reuters.com/article/us-ethiopia-airplane-faa-boe...
  - natch 7y ago
    FAA, right. Trump's pick for FAA head was confirmed only because the majority in the senate (you guess which party) decided to look the other way about allegations that while at Delta, he mistreated a whistleblower who raised safety concerns to him. Oh, and he's a lawyer. I wouldn't trust the current administration's FAA on this. Yes, politics does come into it whether we like it or not.
  - Havoc 7y ago
    Yeah there is a push for using more avg pilots. ...but on mission critical testing with billion dollar implications. You want to tell me they're pulling that name out of a hat?
- cdolan 7y ago
  Correct, I’d wager the best pilots in the world are safety and test pilots.
  - macspoofing 7y ago
    Maybe. I don't know the intricacies of testing flight control software but I imagine Boeing will have a bunch of professional 'test pilots' augmented with regular pilots they 'borrowed'.
kejaed 7y ago
Single Event Upsets are a real thing and if they had a failure mode that missed that, it's a problem that needs to be fixed. https://en.wikipedia.org/wiki/Single-event_upset https://en.wikipedia.org/wiki/Single-event_upset
azalemeth 7y ago
> a simulated edge case involving "gamma rays from space"? People have nearly died because of exactly this situation. See, for example, Quantas Flight 72 [1], in which a pair of sudden, uncommanded pitch-down manoeuvres that caused severe injuries -- including fractures, lacerations and spinal injuries -- to several of the passengers and crew. A long and detailed investigation essentially concluded that these events were most likely caused by the CPUs not being sufficiently rad-hardened. The pilot was diagnosed with PTSD, caused in part by being totally out of control, and quit his career [2, 3]. [1] https://en.wikipedia.org/wiki/Qantas_Flight_72 https://en.wikipedia.org/wiki/Qantas_Flight_72 [2] https://www.smh.com.au/lifestyle/the-untold-story-of-qf72-what-happens-when-psycho-automation-leaves-pilots-powerless-20170511-gw26ae.html https://www.smh.com.au/lifestyle/the-untold-story-of-qf72-wh... [3] https://www.harpercollins.com.au/9780733339745/no-mans-land-the-untold-story-of-automation-and-qf72/ https://www.harpercollins.com.au/9780733339745/no-mans-land-...
- throw1222lak 7y ago
  That's not what the Wikipedia links says: "A number of potential trigger types were investigated, including software bugs, software corruption, hardware faults, electromagnetic interference and the secondary high energy particles generated by cosmic rays. Although a definitive conclusion could not be reached, there was sufficient information from multiple sources to conclude that most of the potential triggers were very unlikely to have been involved. A much more likely scenario was that a marginal hardware weakness of some form made the units susceptible to the effects of some type of environmental factor, which triggered the failure mode." Cosmic rays would be a very convenient excuse. (Cue the ECC RAM lobby, which will probably downvote this.)
Robotbeat 7y ago
Airplanes are flying above the vast majority of the atmosphere, which provides a majority of the shielding for us on Earth. It's a real concern, and extensive care is taken when designing spacecraft electronics for exactly this reason.
devit 7y ago
Is this an issue on non-MAX 737s as well? If not, and thus the affected computer system has been added in the MAX, why not design it properly with 3+ redundant copies of the system given that it was designed in the 2010s when both engineering theory and technological resources are plentiful?
- salawat 7y ago
  It isn't an issue on non-MAX 737's. The flight computers on NG, and others don't have final say level control over the horizontal stabilizer, and there are several overrides the pilots have built in that allow the pilot to lockout trim commands from the Flight Computer, such as hauling back on the control yoke.

by danso 7y ago

branchan 7y ago

I find it hard to believe that they are completely re-designing the avionics/flight computers because of this gamma ray incident. There must be another reason. If it's seriously the main concern, wouldn't it be much easier to just encase the computer in several inches of lead shielding?

Tomte 7y ago

> a simulated edge case involving "gamma rays from space"? Soft-errors are a prime concern when designing safety-critical systems, both in hardware and in software. It's not some outlandish edge case. Incidentally, while soft-errors in an airplane are probably primarily particles from space, on the ground we're still sometimes talking about it, but in reality it's mostly chip packages that are low radioactive and emitting a alpha particle or so.

danso 7y ago
I don't disagree that this is an important thing to test for. I question why this is the reported explanation for why Boeing now decided that the computer systems needed an extensive overhaul. Ostensibly, "gamma rays from space" affecting flight control computers would be an issue that affected Boeing's planes long before MCAS. But it's not the gamma rays that are the reason for the systems redesign, it's the fact that "at least one of the pilots who flew the scenario in a simulator found it difficult to respond in time to maintain control of the plane". Boeing's assumption that pilots could respond quickly enough to a loss of control in the cockpit was an underlying motivation for designing MCAS with inadequate safety measures.
- salawat 7y ago
  Also, there is a regulation that requires no design have a single point of failure capable of resulting in a catastrophic outcome. That's why they have to rearchitect the system. If those bit-flips happened to the Flight Computer in command, they could lose the plane. Therefore, redundancy must be built in. It wasn't originally evaluated as posing a catastrophic outcome in the safety analysis, which is why no one paid it any mind.

Havoc 7y ago

>at least one of the pilots who flew the scenario in a simulator found it difficult to respond And I'm guessing their not using pilots of average skill here...

Operyl 7y ago
According to [0] the FAA was looking for numerous candidates to get a good range of experience, so I would think that you might’ve had at least a few average pilots. [0]: https://www.reuters.com/article/us-ethiopia-airplane-faa-boeing/faa-says-it-will-invite-global-boeing-737-max-pilots-to-simulator-tests-idUSKCN1VC28R https://www.reuters.com/article/us-ethiopia-airplane-faa-boe...
- natch 7y ago
  FAA, right. Trump's pick for FAA head was confirmed only because the majority in the senate (you guess which party) decided to look the other way about allegations that while at Delta, he mistreated a whistleblower who raised safety concerns to him. Oh, and he's a lawyer. I wouldn't trust the current administration's FAA on this. Yes, politics does come into it whether we like it or not.
- Havoc 7y ago
  Yeah there is a push for using more avg pilots. ...but on mission critical testing with billion dollar implications. You want to tell me they're pulling that name out of a hat?
cdolan 7y ago
Correct, I’d wager the best pilots in the world are safety and test pilots.
- macspoofing 7y ago
  Maybe. I don't know the intricacies of testing flight control software but I imagine Boeing will have a bunch of professional 'test pilots' augmented with regular pilots they 'borrowed'.

kejaed 7y ago

Single Event Upsets are a real thing and if they had a failure mode that missed that, it's a problem that needs to be fixed. https://en.wikipedia.org/wiki/Single-event_upset https://en.wikipedia.org/wiki/Single-event_upset

azalemeth 7y ago

> a simulated edge case involving "gamma rays from space"? People have nearly died because of exactly this situation. See, for example, Quantas Flight 72 [1], in which a pair of sudden, uncommanded pitch-down manoeuvres that caused severe injuries -- including fractures, lacerations and spinal injuries -- to several of the passengers and crew. A long and detailed investigation essentially concluded that these events were most likely caused by the CPUs not being sufficiently rad-hardened. The pilot was diagnosed with PTSD, caused in part by being totally out of control, and quit his career [2, 3]. [1] https://en.wikipedia.org/wiki/Qantas_Flight_72 https://en.wikipedia.org/wiki/Qantas_Flight_72 [2] https://www.smh.com.au/lifestyle/the-untold-story-of-qf72-what-happens-when-psycho-automation-leaves-pilots-powerless-20170511-gw26ae.html https://www.smh.com.au/lifestyle/the-untold-story-of-qf72-wh... [3] https://www.harpercollins.com.au/9780733339745/no-mans-land-the-untold-story-of-automation-and-qf72/ https://www.harpercollins.com.au/9780733339745/no-mans-land-...

throw1222lak 7y ago
That's not what the Wikipedia links says: "A number of potential trigger types were investigated, including software bugs, software corruption, hardware faults, electromagnetic interference and the secondary high energy particles generated by cosmic rays. Although a definitive conclusion could not be reached, there was sufficient information from multiple sources to conclude that most of the potential triggers were very unlikely to have been involved. A much more likely scenario was that a marginal hardware weakness of some form made the units susceptible to the effects of some type of environmental factor, which triggered the failure mode." Cosmic rays would be a very convenient excuse. (Cue the ECC RAM lobby, which will probably downvote this.)

Robotbeat 7y ago

Airplanes are flying above the vast majority of the atmosphere, which provides a majority of the shielding for us on Earth. It's a real concern, and extensive care is taken when designing spacecraft electronics for exactly this reason.

devit 7y ago

Is this an issue on non-MAX 737s as well? If not, and thus the affected computer system has been added in the MAX, why not design it properly with 3+ redundant copies of the system given that it was designed in the 2010s when both engineering theory and technological resources are plentiful?

salawat 7y ago
It isn't an issue on non-MAX 737's. The flight computers on NG, and others don't have final say level control over the horizontal stabilizer, and there are several overrides the pilots have built in that allow the pilot to lockout trim commands from the Flight Computer, such as hauling back on the control yoke.