6 ms·

Its unfortunate they don’t calculate how big a difference it made. They’d calculated a 170ft margin and stopped with 30ft margin and I’m curious what their brak

by oakmad 5y ago

Its unfortunate they don’t calculate how big a difference it made. They’d calculated a 170ft margin and stopped with 30ft margin and I’m curious what their braking delta was for that 700ft of deterioration. « With three FCPCs inoperative, actual remaining runway distance (30 feet margin) of the occurrence flight was shorter than the calculated value (172 feet margin), possibly due to tailwinds, runway conditions, and manual braking as these factors might increase the braking distance. » I get sucked into how all the little things that are not right make such a big difference in these kind of scenarios.

colechristensen 5y ago
Complex systems and aerospace particularly are dominated by little things. Failure or near misses are never single cause, those are all designed for. When fails to happen it is almost always a conspiracy of serval things out put together any one of which would have mostly prevented the incident. There is a lot that practices involving life critical complex systems can teach other fields.
- dmurray 5y ago
  Agreed, and let's not lose sight of the fact that...this was a successful landing. Everyone walked away from it and the passengers likely never knew anything went wrong. Four hopefully independent things went wrong here: three computer failures plus less-than-documented braking performance. Additionally, there were at least two aggravating circumstances: wet conditions and a tailwind landing. Part of the investigation is to find out if there was a fourth or fifth system failure (poor pilot reaction time? Rubber level on the runway unacceptable? Either is plausible, but far from indicated by the report so far). One extra thing going wrong here, in the wrong direction (anything that impaired braking or pilot reaction time) would likely have led to loss of life. Investigating near misses like this, and not only being exercised once five things go wrong and a hundred people die, is a sign of a healthy safety culture.
  - AnimalMuppet 5y ago
    > the passengers likely never knew anything went wrong. If the deceleration varied as much as the report said, then the passengers probably could tell. That was very different from a normal landing. If that wasn't enough, being towed to the terminal might have given them another clue. > One extra thing going wrong here, in the wrong direction (anything that impaired braking or pilot reaction time) would likely have led to loss of life. Well, it would have lead to the plane running off the end of the runway. What's past the end of that particular runway? A cliff? A river? Or just another 100 meters of grass leading up to a perimeter fence, then more flat ground for some distance beyond it? If it doesn't overrun the runway too far (say, 100 or 200 meters), no, that doesn't seem likely to lead to loss of life - not unless there's some specific hazard there.
    - dmurray 5y ago
      According to the first comment on TFA, it's in a built up area. I checked Google maps [0] and it's pretty bad: 50m of tarmac (no EMAS I think), 50m of grass, then a minor road with commercial buildings. Regardless, that's one to be considered another aggravating circumstance, not an additional failure. When deciding whether this was a close call, you can treat it as if every runway is wet and in a permanent tailwind and immediately followed by a wooden building full of schoolchildren. [0] https://maps.app.goo.gl/u4eFmqDAysMVbbWC8 https://maps.app.goo.gl/u4eFmqDAysMVbbWC8
      - AnimalMuppet 5y ago
        Oh, absolutely. You treat it as if there is no margin. And you don't put wooden buildings full of schoolchildren immediately past the end of runways.
      - account42 5y ago
        Unless I am mistaken, runway 10 is west to east so it would have gone through the parking lot and then into the river. That also the direction I remember most planes landing there.
  - 5y ago
gadiyar 5y ago
I read this in an old 1950s era Readers Digest (Harper Subscribers only). Interesting (fictional) article about a jet that was doomed before takeoff by an accumulation of a number of small things each of which would not individually have caused an incident but taken together were fatal. https://harpers.org/archive/1957/09/the-jet-that-crashed-before-take-off/ https://harpers.org/archive/1957/09/the-jet-that-crashed-bef... Edit: Accessible version of the article here. https://books.google.co.in/books?id=2gk-2rP34LIC&pg=RA2-PA14&lpg=RA2-PA14&dq=beirne+lay+jet+crashed+before+tskeoff&source=bl&ots=HxvoYfS4yR&sig=ACfU3U3OA3bURmayOwA34QAqRToqZ_Dgsw&hl=en&sa=X&ved=2ahUKEwjV84__sOryAhUPfH0KHaPfDicQ6AF6BAgsEAI#v=onepage&q=beirne%20lay%20jet%20crashed%20before%20takeoff&f=true https://books.google.co.in/books?id=2gk-2rP34LIC&pg=RA2-PA14...

by oakmad 5y ago

colechristensen 5y ago

Complex systems and aerospace particularly are dominated by little things. Failure or near misses are never single cause, those are all designed for. When fails to happen it is almost always a conspiracy of serval things out put together any one of which would have mostly prevented the incident. There is a lot that practices involving life critical complex systems can teach other fields.

dmurray 5y ago
Agreed, and let's not lose sight of the fact that...this was a successful landing. Everyone walked away from it and the passengers likely never knew anything went wrong. Four hopefully independent things went wrong here: three computer failures plus less-than-documented braking performance. Additionally, there were at least two aggravating circumstances: wet conditions and a tailwind landing. Part of the investigation is to find out if there was a fourth or fifth system failure (poor pilot reaction time? Rubber level on the runway unacceptable? Either is plausible, but far from indicated by the report so far). One extra thing going wrong here, in the wrong direction (anything that impaired braking or pilot reaction time) would likely have led to loss of life. Investigating near misses like this, and not only being exercised once five things go wrong and a hundred people die, is a sign of a healthy safety culture.
- AnimalMuppet 5y ago
  > the passengers likely never knew anything went wrong. If the deceleration varied as much as the report said, then the passengers probably could tell. That was very different from a normal landing. If that wasn't enough, being towed to the terminal might have given them another clue. > One extra thing going wrong here, in the wrong direction (anything that impaired braking or pilot reaction time) would likely have led to loss of life. Well, it would have lead to the plane running off the end of the runway. What's past the end of that particular runway? A cliff? A river? Or just another 100 meters of grass leading up to a perimeter fence, then more flat ground for some distance beyond it? If it doesn't overrun the runway too far (say, 100 or 200 meters), no, that doesn't seem likely to lead to loss of life - not unless there's some specific hazard there.
  - dmurray 5y ago
    According to the first comment on TFA, it's in a built up area. I checked Google maps [0] and it's pretty bad: 50m of tarmac (no EMAS I think), 50m of grass, then a minor road with commercial buildings. Regardless, that's one to be considered another aggravating circumstance, not an additional failure. When deciding whether this was a close call, you can treat it as if every runway is wet and in a permanent tailwind and immediately followed by a wooden building full of schoolchildren. [0] https://maps.app.goo.gl/u4eFmqDAysMVbbWC8 https://maps.app.goo.gl/u4eFmqDAysMVbbWC8
    - AnimalMuppet 5y ago
      Oh, absolutely. You treat it as if there is no margin. And you don't put wooden buildings full of schoolchildren immediately past the end of runways.
    - account42 5y ago
      Unless I am mistaken, runway 10 is west to east so it would have gone through the parking lot and then into the river. That also the direction I remember most planes landing there.
- 5y ago

gadiyar 5y ago

I read this in an old 1950s era Readers Digest (Harper Subscribers only). Interesting (fictional) article about a jet that was doomed before takeoff by an accumulation of a number of small things each of which would not individually have caused an incident but taken together were fatal. https://harpers.org/archive/1957/09/the-jet-that-crashed-before-take-off/ https://harpers.org/archive/1957/09/the-jet-that-crashed-bef... Edit: Accessible version of the article here. https://books.google.co.in/books?id=2gk-2rP34LIC&pg=RA2-PA14&lpg=RA2-PA14&dq=beirne+lay+jet+crashed+before+tskeoff&source=bl&ots=HxvoYfS4yR&sig=ACfU3U3OA3bURmayOwA34QAqRToqZ_Dgsw&hl=en&sa=X&ved=2ahUKEwjV84__sOryAhUPfH0KHaPfDicQ6AF6BAgsEAI#v=onepage&q=beirne%20lay%20jet%20crashed%20before%20takeoff&f=true https://books.google.co.in/books?id=2gk-2rP34LIC&pg=RA2-PA14...