3 ms·

> In reality, aircraft autopilots don't do what most people think they do (they require constant monitoring by pilots) Tangent: what does an airplane's autopil

by derefr 3y ago

> In reality, aircraft autopilots don't do what most people think they do (they require constant monitoring by pilots) Tangent: what does an airplane's autopilot do? I always assumed it was basically doing lane-keeping within virtual flight-path lanes we've drawn in the sky. (Like the virtual 3D traffic grid above cities in depictions of cities with flying cars, but spread across the Atlantic.)

rpmisms 3y ago
Follows heading and speed instructions, newer models can also be programmed using the flight plan to follow more complex directions. Autoland is also a thing now. Commercial aviation is a gigantic set of checklists, autopilot progressively does more of the checklist items. Autopilot is hilariously a fantastic name for the Tesla system. If people knew anything about how commercial aviation systems actually work, they would understand this
- derefr 3y ago
  Sounds more like very simple cruise control, at least for the main leg of the flight. Though I suppose "follows heading instructions" can be complex? Does an autopilot "lane keep", in the sense of issuing corrections after hitting a turbulence "pothole", to return it to the flight path? Or does it just beep and shut off, telling the pilot to fix the heading? One thing I would expect "sufficiently-advanced autopilot" to do, would be to fly under/over/around large regions of turbulence on its own, and to then return to the original heading. Like driving around a large pothole, but the pothole can be 30 mins of flight-time large. (I'm guessing that this technology exists, but currently only in military aviation for long-distance fly-by-wire UAVs "swarms", not in commercial aviation for piloted aircraft.) Also, is there any actual logic for obstacle avoidance? If you steer two autopiloted planes toward each-other, do they "take evasive maneuvers", or do they just beep very loudly to get the pilots to do that? ...also, is the on-the-ground taxi-ing process automated? Because that seems like drudge-work that really could be automated — airports really seem like they have enough information about where everything is on the ground, and enough very strict rules about precedence when driving around the tarmac. (Heck, in theory the airport could centrally control taxi-ing with little tugboat-like robots that hug each plane's front wheel — I think I've seen this before?) And automating taxi-ing before take-off in particular, would free up some extremely critical time that could be used to be more thorough with preflight inspection.
  - lstodd 3y ago
    > Sounds more like very simple cruise control, at least for the main leg of the flight. And it is. Although it had been already abused to hell and back, see "children of the magenta", ca 1997. Turbulence is undetectable, TCAS is shit and there is no replacement for a warm butt in the chair which hopefully understands how the thing handles, especially in the hell on the ground that the major airports are.
    - derefr 3y ago
      > Turbulence is undetectable Not inherently, and we're getting there. See e.g. https://www.mdpi.com/1424-8220/18/3/798 https://www.mdpi.com/1424-8220/18/3/798 for the use of time-of-flight sensor sampling (i.e. a depth-of-field camera) to build a picture of local turbulence (in water rather than air, but the principle translates.)
      - lstodd 3y ago
        Not inherently, but not practical either. The paper talks about refractive index , and while that may be useful for liquids, it does nothing for low-pressure low-density gas like the air. Eh, it water I think phased array sonar could depict turbulence better than an optical system. In air -- no such luck. It's just centuries-old rule of "do not fly into clouds and otherwise hope the plane doesn't break apart".
  - rpmisms 3y ago
    Autopilot will not automatically route itself around turbulence, that would be a path entered by the pilots. It can correct from being blown off course. Autopilot is by necessity a direction following system, it must not make its own choices about navigation. In commercial flight, collisions are incredibly rare and unlikely, and there are already systems in place to avoid them, but there are separate systems to warn about proximity. Essentially, there is a transponder system that alerts with increasing frequency at closer distances. Taxiing is not automated, and only older planes need to be towed with tug trucks. The idea behind autopilot as it exists is to lower the pilots' workload so that they have more mental capacity available if something serious happens. Taxing is a much more limited problem space, so limited payoff in automating. For the record, I'm not a pilot, just an enthusiast. The systems are all pretty well documented if you're interested.
- rootusrootus 3y ago
  > Autopilot is hilariously a fantastic name for the Tesla system. If people knew anything about how commercial aviation systems actually work, they would understand this This seems pretty contradictory. We require a lot of expensive training and certification before we declare someone a pilot and let them fly a plane with autopilot. Knowing that, I would suggeset that using the term 'autopilot' in a car that can be driven by untrained individuals is probably the wrong choice. We should use terminology that is crystal clear to Joe Average.
  - rpmisms 3y ago
    Drivers have driver's licenses. Pilots have pilot's licenses. Also, any idiot can take flight lessons and fly a plane with basic autopilot, no license required.
cesarb 3y ago
> Tangent: what does an airplane's autopilot do? I always assumed it was basically doing lane-keeping within virtual flight-path lanes we've drawn in the sky. It's even simpler than that: a basic autopilot can keep a set heading and altitude without constant adjustments from the pilot, and a basic autothrottle can keep a set speed without constant adjustment of the throttle from the pilot. The pilot gives them simple instructions like "heading 123" and "altitude 1234" and "speed 200" through buttons on the aircraft's panel. This allows for hands-free flying (the pilot doesn't have to hold the controls all the time when the autopilot and autothrottle are active). More advanced autopilots can follow parts of the flight plan, like "fly to waypoint ABC then to waypoint DEF then to waypoint GHI", automatically changing their setting to the next one every time a relevant waypoint is reached, but even then the pilot still has to give it instructions regularly (for instance, when a controller tells the pilot through the radio to use a specific altitude, the pilot has to set that altitude in the autopilot). And, of course, the pilot still has to be ready to take control at a moment's notice; whenever the autopilot sees something it doesn't like, it deactivates (with a warning tone and blinking lights).
dsr_ 3y ago
Heading control measures the current heading, subtracts the set heading, and applies rudder to bring the difference back towards zero. Speed control does the same with speed sensors and the throttle. That's why aircraft autopilots have been around since 1912. https://en.wikipedia.org/wiki/Autopilot https://en.wikipedia.org/wiki/Autopilot

by derefr 3y ago

rpmisms 3y ago

Follows heading and speed instructions, newer models can also be programmed using the flight plan to follow more complex directions. Autoland is also a thing now. Commercial aviation is a gigantic set of checklists, autopilot progressively does more of the checklist items. Autopilot is hilariously a fantastic name for the Tesla system. If people knew anything about how commercial aviation systems actually work, they would understand this

derefr 3y ago
Sounds more like very simple cruise control, at least for the main leg of the flight. Though I suppose "follows heading instructions" can be complex? Does an autopilot "lane keep", in the sense of issuing corrections after hitting a turbulence "pothole", to return it to the flight path? Or does it just beep and shut off, telling the pilot to fix the heading? One thing I would expect "sufficiently-advanced autopilot" to do, would be to fly under/over/around large regions of turbulence on its own, and to then return to the original heading. Like driving around a large pothole, but the pothole can be 30 mins of flight-time large. (I'm guessing that this technology exists, but currently only in military aviation for long-distance fly-by-wire UAVs "swarms", not in commercial aviation for piloted aircraft.) Also, is there any actual logic for obstacle avoidance? If you steer two autopiloted planes toward each-other, do they "take evasive maneuvers", or do they just beep very loudly to get the pilots to do that? ...also, is the on-the-ground taxi-ing process automated? Because that seems like drudge-work that really could be automated — airports really seem like they have enough information about where everything is on the ground, and enough very strict rules about precedence when driving around the tarmac. (Heck, in theory the airport could centrally control taxi-ing with little tugboat-like robots that hug each plane's front wheel — I think I've seen this before?) And automating taxi-ing before take-off in particular, would free up some extremely critical time that could be used to be more thorough with preflight inspection.
- lstodd 3y ago
  > Sounds more like very simple cruise control, at least for the main leg of the flight. And it is. Although it had been already abused to hell and back, see "children of the magenta", ca 1997. Turbulence is undetectable, TCAS is shit and there is no replacement for a warm butt in the chair which hopefully understands how the thing handles, especially in the hell on the ground that the major airports are.
  - derefr 3y ago
    > Turbulence is undetectable Not inherently, and we're getting there. See e.g. https://www.mdpi.com/1424-8220/18/3/798 https://www.mdpi.com/1424-8220/18/3/798 for the use of time-of-flight sensor sampling (i.e. a depth-of-field camera) to build a picture of local turbulence (in water rather than air, but the principle translates.)
    - lstodd 3y ago
      Not inherently, but not practical either. The paper talks about refractive index , and while that may be useful for liquids, it does nothing for low-pressure low-density gas like the air. Eh, it water I think phased array sonar could depict turbulence better than an optical system. In air -- no such luck. It's just centuries-old rule of "do not fly into clouds and otherwise hope the plane doesn't break apart".
- rpmisms 3y ago
  Autopilot will not automatically route itself around turbulence, that would be a path entered by the pilots. It can correct from being blown off course. Autopilot is by necessity a direction following system, it must not make its own choices about navigation. In commercial flight, collisions are incredibly rare and unlikely, and there are already systems in place to avoid them, but there are separate systems to warn about proximity. Essentially, there is a transponder system that alerts with increasing frequency at closer distances. Taxiing is not automated, and only older planes need to be towed with tug trucks. The idea behind autopilot as it exists is to lower the pilots' workload so that they have more mental capacity available if something serious happens. Taxing is a much more limited problem space, so limited payoff in automating. For the record, I'm not a pilot, just an enthusiast. The systems are all pretty well documented if you're interested.
rootusrootus 3y ago
> Autopilot is hilariously a fantastic name for the Tesla system. If people knew anything about how commercial aviation systems actually work, they would understand this This seems pretty contradictory. We require a lot of expensive training and certification before we declare someone a pilot and let them fly a plane with autopilot. Knowing that, I would suggeset that using the term 'autopilot' in a car that can be driven by untrained individuals is probably the wrong choice. We should use terminology that is crystal clear to Joe Average.
- rpmisms 3y ago
  Drivers have driver's licenses. Pilots have pilot's licenses. Also, any idiot can take flight lessons and fly a plane with basic autopilot, no license required.

cesarb 3y ago

> Tangent: what does an airplane's autopilot do? I always assumed it was basically doing lane-keeping within virtual flight-path lanes we've drawn in the sky. It's even simpler than that: a basic autopilot can keep a set heading and altitude without constant adjustments from the pilot, and a basic autothrottle can keep a set speed without constant adjustment of the throttle from the pilot. The pilot gives them simple instructions like "heading 123" and "altitude 1234" and "speed 200" through buttons on the aircraft's panel. This allows for hands-free flying (the pilot doesn't have to hold the controls all the time when the autopilot and autothrottle are active). More advanced autopilots can follow parts of the flight plan, like "fly to waypoint ABC then to waypoint DEF then to waypoint GHI", automatically changing their setting to the next one every time a relevant waypoint is reached, but even then the pilot still has to give it instructions regularly (for instance, when a controller tells the pilot through the radio to use a specific altitude, the pilot has to set that altitude in the autopilot). And, of course, the pilot still has to be ready to take control at a moment's notice; whenever the autopilot sees something it doesn't like, it deactivates (with a warning tone and blinking lights).

dsr_ 3y ago

Heading control measures the current heading, subtracts the set heading, and applies rudder to bring the difference back towards zero. Speed control does the same with speed sensors and the throttle. That's why aircraft autopilots have been around since 1912. https://en.wikipedia.org/wiki/Autopilot https://en.wikipedia.org/wiki/Autopilot