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What I don't understand (and I'm being honest here) is that between GPSs, computers, and HUDs, how do these errors still happen? I mean that if your GPS sees

What I don't understand (and I'm being honest here) is that between GPSs, computers, and HUDs, how do these errors still happen? I mean that if your GPS sees you're aiming at the wrong runway, why can't it alert the pilot (and/or tower) that it's going to miss.

isomorphic 9y ago
I don't think GPS is accurate enough for that sort of thing, you'd need ground radar, working with onboard computers that understand which runway you're cleared for, etc. (I'm not a pilot, I'm speculating.) If you read the Guardian article from planetjones' comment: https://www.theguardian.com/business/2017/aug/03/air-canada-near-miss-picture-shows-how-close-planes-came-to-crashing https://www.theguardian.com/business/2017/aug/03/air-canada-... Quoting: The investigators said that as the Air Canada jet approached the taxiway just before midnight after a flight from Toronto, it was so far off course that it did not appear on a radar system used to prevent runway collisions. The next paragraph states they are working on improving that.
- mseebach 9y ago
  It's called ILS, Instrument Landing System, and it's been around for literally 80 years. > The first landing of a scheduled U.S. passenger airliner using ILS was on January 26, 1938, when a Pennsylvania Central Airlines Boeing 247D flew from Washington, D.C., to Pittsburgh, Pennsylvania, and landed in a snowstorm using only the Instrument Landing System https://en.wikipedia.org/wiki/Instrument_landing_system https://en.wikipedia.org/wiki/Instrument_landing_system Presumably they must have done a visual approach or something, because their ILS would have been outright incapable of directing them down the taxiway, as it's for obvious reasons not equipped for ILS approaches.
  - jbg_ 9y ago
    ILS is separate from the radar system mentioned by parent. ILS uses directional radio signals from each end of the runway to provide a glideslope and lateral guidance, not radar. The signals are transmitted from the ground and used for guidance by the aircraft. No part of ILS could alert ATC to anything since the ground stations are only transmitters.
    - mseebach 9y ago
      Yes, I know. But it's analogous to the GPS system the parents are discussing.
      - throwanem 9y ago
        Trouble there is that, at least to the best of my knowledge, ILS glide slope and localizer are generally only surfaced in the cockpit as a pair of bugs vertically and horizontally peripheral to the artificial horizon indicator. If you're already having a helmet fire, these are likely easy to overlook, and there's no horn or anything. (But as has been pointed out here by several other commenters before now - if you're already having a helmet fire, another horn may not do any good.)
        mseebach 9y ago
        I don't think there's any indication that these pilots were under any kind of undue stress when they lined up their approach? If at any point during the several minutes of their final approach they'd looked even once at their ILS they'd have seen that they were way off.
        throwanem 9y ago
        Final approach is the most stressful two or three minutes of an otherwise unexceptional flight; there's a great deal to do, and very little time in which to do it, during a period in which the aircraft's proximity to the ground, and low available energy, make it very easy for what would otherwise be a minor mishap to instantly place everyone aboard in imminent danger of death. I don't suppose I would call such stress "undue", since every commercial flight ideally ends with a landing. But the probability of helmet fire is directly proportional to the degree of cockpit stress, and the ILS alignment indicators are very easy to overlook. I suspect the user interface could be improved, but I'm not nearly familiar enough with the subject domain to imagine how.
        mseebach 9y ago
  - andrewfree 9y ago
    They were sitting there because of a bomb threat at another airport and that was the only storage space. Did you read the article?
    - mseebach 9y ago
      It's irrelevant why they were there, it's a taxi way, it's fine, indeed expected, for planes to hang out there. The important bit was why the AC tried to land there and the crew confirming their approach on ILS would have prevented that.
matt_wulfeck 9y ago
I'm wondering the same thing. Why don't planes land themselves at this point?
- kpil 9y ago
  The main reason is that computers aren't very smart although I know that even some developers think that. Actually they can autoland but not everywhere and then you still need to tell them where, basically tune them in on the right glide path. Then you really need to be prepared to take over any second, which is a dangerous position on its own. (Just like all self driving cars right now.) It's still possible to select the wrong ILS beacon or entering the wrong speed or whatever, and something can still show up in front of the plane. It's just better in low visibility where you otherwise manually have to follow the ILS 'needles'. Didn't a plane crash there killing some chinese schoolgirls just because the pilots forgot to set the correct speed. Either it was set too low or they set it but did not activate it. And then the monitoring pilot forgot to monitor the speed since the autopilot never fails...
  - greenhouse_gas 9y ago
    >Actually they can autoland but not everywhere and then you still need to tell them where, basically tune them in on the right glide path. Why can't the ATC or Pilot guide the computers to the right glidepath? And most importantly, if you're not going in that glidepath, you should get a major alarm, with ATC warned (so they can manually tell the pilot to abort).
    - kpil 9y ago
      They do and they did? But it's primarily a manual process. There are automated warning systems such as ACAS and separation warnings, but I don't think it would be possible to program something that could understand what's going on with all the traffic all the time and just generally warn if it's not looking right...
  - ohwaitnvm 9y ago
    Asiana 214 - https://en.m.wikipedia.org/wiki/Asiana_Airlines_Flight_214 https://en.m.wikipedia.org/wiki/Asiana_Airlines_Flight_214 "Over-reliance on automation and lack of systems understanding by the pilots were cited as major factors contributing to the accident."

isomorphic 9y ago

I don't think GPS is accurate enough for that sort of thing, you'd need ground radar, working with onboard computers that understand which runway you're cleared for, etc. (I'm not a pilot, I'm speculating.) If you read the Guardian article from planetjones' comment: https://www.theguardian.com/business/2017/aug/03/air-canada-near-miss-picture-shows-how-close-planes-came-to-crashing https://www.theguardian.com/business/2017/aug/03/air-canada-... Quoting: The investigators said that as the Air Canada jet approached the taxiway just before midnight after a flight from Toronto, it was so far off course that it did not appear on a radar system used to prevent runway collisions. The next paragraph states they are working on improving that.

mseebach 9y ago
It's called ILS, Instrument Landing System, and it's been around for literally 80 years. > The first landing of a scheduled U.S. passenger airliner using ILS was on January 26, 1938, when a Pennsylvania Central Airlines Boeing 247D flew from Washington, D.C., to Pittsburgh, Pennsylvania, and landed in a snowstorm using only the Instrument Landing System https://en.wikipedia.org/wiki/Instrument_landing_system https://en.wikipedia.org/wiki/Instrument_landing_system Presumably they must have done a visual approach or something, because their ILS would have been outright incapable of directing them down the taxiway, as it's for obvious reasons not equipped for ILS approaches.
- jbg_ 9y ago
  ILS is separate from the radar system mentioned by parent. ILS uses directional radio signals from each end of the runway to provide a glideslope and lateral guidance, not radar. The signals are transmitted from the ground and used for guidance by the aircraft. No part of ILS could alert ATC to anything since the ground stations are only transmitters.
  - mseebach 9y ago
    Yes, I know. But it's analogous to the GPS system the parents are discussing.
    - throwanem 9y ago
      Trouble there is that, at least to the best of my knowledge, ILS glide slope and localizer are generally only surfaced in the cockpit as a pair of bugs vertically and horizontally peripheral to the artificial horizon indicator. If you're already having a helmet fire, these are likely easy to overlook, and there's no horn or anything. (But as has been pointed out here by several other commenters before now - if you're already having a helmet fire, another horn may not do any good.)
      - mseebach 9y ago
        I don't think there's any indication that these pilots were under any kind of undue stress when they lined up their approach? If at any point during the several minutes of their final approach they'd looked even once at their ILS they'd have seen that they were way off.
        throwanem 9y ago
        Final approach is the most stressful two or three minutes of an otherwise unexceptional flight; there's a great deal to do, and very little time in which to do it, during a period in which the aircraft's proximity to the ground, and low available energy, make it very easy for what would otherwise be a minor mishap to instantly place everyone aboard in imminent danger of death. I don't suppose I would call such stress "undue", since every commercial flight ideally ends with a landing. But the probability of helmet fire is directly proportional to the degree of cockpit stress, and the ILS alignment indicators are very easy to overlook. I suspect the user interface could be improved, but I'm not nearly familiar enough with the subject domain to imagine how.
        mseebach 9y ago
- andrewfree 9y ago
  They were sitting there because of a bomb threat at another airport and that was the only storage space. Did you read the article?
  - mseebach 9y ago
    It's irrelevant why they were there, it's a taxi way, it's fine, indeed expected, for planes to hang out there. The important bit was why the AC tried to land there and the crew confirming their approach on ILS would have prevented that.

matt_wulfeck 9y ago

I'm wondering the same thing. Why don't planes land themselves at this point?

kpil 9y ago
The main reason is that computers aren't very smart although I know that even some developers think that. Actually they can autoland but not everywhere and then you still need to tell them where, basically tune them in on the right glide path. Then you really need to be prepared to take over any second, which is a dangerous position on its own. (Just like all self driving cars right now.) It's still possible to select the wrong ILS beacon or entering the wrong speed or whatever, and something can still show up in front of the plane. It's just better in low visibility where you otherwise manually have to follow the ILS 'needles'. Didn't a plane crash there killing some chinese schoolgirls just because the pilots forgot to set the correct speed. Either it was set too low or they set it but did not activate it. And then the monitoring pilot forgot to monitor the speed since the autopilot never fails...
- greenhouse_gas 9y ago
  >Actually they can autoland but not everywhere and then you still need to tell them where, basically tune them in on the right glide path. Why can't the ATC or Pilot guide the computers to the right glidepath? And most importantly, if you're not going in that glidepath, you should get a major alarm, with ATC warned (so they can manually tell the pilot to abort).
  - kpil 9y ago
    They do and they did? But it's primarily a manual process. There are automated warning systems such as ACAS and separation warnings, but I don't think it would be possible to program something that could understand what's going on with all the traffic all the time and just generally warn if it's not looking right...
- ohwaitnvm 9y ago
  Asiana 214 - https://en.m.wikipedia.org/wiki/Asiana_Airlines_Flight_214 https://en.m.wikipedia.org/wiki/Asiana_Airlines_Flight_214 "Over-reliance on automation and lack of systems understanding by the pilots were cited as major factors contributing to the accident."