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I actually think autopilot for an airplane is much, much safer than in a car. Airliners fly at several tens of thousands of feet in altitude and have glide ra

I actually think autopilot for an airplane is much, much safer than in a car. Airliners fly at several tens of thousands of feet in altitude and have glide ratios that are rather impressive, between 10:1 and 30:1 meaning that at cruise (where airliners spend most of their time on autopilot) the flight crew has several tens of minutes to figure out what's going wrong. Even if the airplane loses power completely! Further, these airplanes are kept fairly widely separated in altitude and the skies are rather sparse, so collisions are something to be avoided but it's not all that hard. In a car though, the safety margins are much, much lower. Because there are vehicles everywhere the time to collision is probably measured in milliseconds rather than minutes. Because there are no redundant systems to ensure safety once the car "realizes" it can't control itself anymore you're prettymuch hosed. Are any of the regulations on self-driving cars taking this into account and at least mandating that the control system has sufficient battery back-up for it to at least TRY and gracefully de-energize the vehicle? Once cars become self-driving you can't really rely on humans to suddenly jump in and take the wheel and save the day. They're going to be asleep or not paying attention or watching a movie or whatever. And if they are going to be required to watch the road paying 100% attention to what they car is doing, what's the advantage of having the car drive itself? You're in a constant battle of "what's the car going to do?!" which is actually more tiring than just driving it yourself. An easy solution might require that self-driving cars only self-drive in lanes which are adjacent to a shoulder of sufficient width giving the car an out that requires only minimal controls, so basically far-right or far-left lanes on a freeway. A self-driving car might also need to have multiple, redundant regenerative braking systems so that it can power itself enough to power the controls to safely guide the car to a stop. But then it also needs multiple control systems so that if one of those fails, the car isn't out of control. The economics of having an autopilot on an airliner (which costs many millions of dollars) and a car (95% of which cost less than $100k) are really, really different.

mikeash 12y ago
I think it's clear enough that you're right just from experience. We've had autopilots of various kinds of airplanes for decades, and they can fly pretty much autonomously at this point. But in this one specific area, of how to handle failures and returning control to the human, I think cars have the advantage. It just doesn't compensate for all the other places where a car autopilot is vastly more difficult.
- msandford 12y ago
  So my gut reaction to "cars have the advantage" is "you're clearly wrong!" but that's not really polite or enlightening. Rather than argue about it (which I'm sure we could do endlessly) I'd like to know why or how you think that cars have the advantage. I saw earlier that you posted "because you can always have the car pull over to sort a problem out" and I would agree that provided the car can still control itself, yes it could do that. I guess my assumption on when the car tells a human being to take control are in a few circumstances: 1. it loses the ability to control a driving input that ostensibly the driver still has the ability to control (steering servo fails) 2. it loses the ability to control a driving input that the driver also can't control (tire blowout) 3. it doesn't know what to do or can't make a decision so the driver is the tiebreaker (crash imminent, road disappears, brand new road with no map data, etc) 4. it loses a sensor input completely or starts getting data that it considers garbage and thus can't safely operate the vehicle (LIDAR or camera fails) 5. loss of power so that autopilot just straight up fails I could probably think of some more scenarios but the point isn't to be exhaustive but illustrative. So in some of these circumstances the car does have an opportunity to pull over and wake the driver up and say "hey you need to drive now" but in others, it's going to be split second. If ALL the car failure modes resulted in the car pulling over and the driver taking back over at his/her leisure then I would 100% agree with you. But there clearly are failure modes where the driver is going to get put back in the control loop with little/no warning and be asked to make a decision perhaps faster than they can wake up and/or process the scene and catch up enough to decide well. So basically what you have to do is make some kind of guarantee about "the car will never ask the driver to take over with less than 60 seconds of notice" or something like that. But the hardware cost to enable you to make that kind of guarantee is substantial; sensors, battery backups, autopilot systems, actuators, etc all in triplicate. And I don't know that you can do with just two because in the situation where you go from two to one you don't have any kind of ability to determine if one of the pieces of software is malfunctioning due to memory corruption. Although the price of doing all this is going down drastically I suspect that it'll be a while before people are willing to pay enough to get the kind of redundancy they have in airplanes. So what am I missing? I'm really curious.
  - mikeash 12y ago

mikeash 12y ago

I think it's clear enough that you're right just from experience. We've had autopilots of various kinds of airplanes for decades, and they can fly pretty much autonomously at this point. But in this one specific area, of how to handle failures and returning control to the human, I think cars have the advantage. It just doesn't compensate for all the other places where a car autopilot is vastly more difficult.

msandford 12y ago
So my gut reaction to "cars have the advantage" is "you're clearly wrong!" but that's not really polite or enlightening. Rather than argue about it (which I'm sure we could do endlessly) I'd like to know why or how you think that cars have the advantage. I saw earlier that you posted "because you can always have the car pull over to sort a problem out" and I would agree that provided the car can still control itself, yes it could do that. I guess my assumption on when the car tells a human being to take control are in a few circumstances: 1. it loses the ability to control a driving input that ostensibly the driver still has the ability to control (steering servo fails) 2. it loses the ability to control a driving input that the driver also can't control (tire blowout) 3. it doesn't know what to do or can't make a decision so the driver is the tiebreaker (crash imminent, road disappears, brand new road with no map data, etc) 4. it loses a sensor input completely or starts getting data that it considers garbage and thus can't safely operate the vehicle (LIDAR or camera fails) 5. loss of power so that autopilot just straight up fails I could probably think of some more scenarios but the point isn't to be exhaustive but illustrative. So in some of these circumstances the car does have an opportunity to pull over and wake the driver up and say "hey you need to drive now" but in others, it's going to be split second. If ALL the car failure modes resulted in the car pulling over and the driver taking back over at his/her leisure then I would 100% agree with you. But there clearly are failure modes where the driver is going to get put back in the control loop with little/no warning and be asked to make a decision perhaps faster than they can wake up and/or process the scene and catch up enough to decide well. So basically what you have to do is make some kind of guarantee about "the car will never ask the driver to take over with less than 60 seconds of notice" or something like that. But the hardware cost to enable you to make that kind of guarantee is substantial; sensors, battery backups, autopilot systems, actuators, etc all in triplicate. And I don't know that you can do with just two because in the situation where you go from two to one you don't have any kind of ability to determine if one of the pieces of software is malfunctioning due to memory corruption. Although the price of doing all this is going down drastically I suspect that it'll be a while before people are willing to pay enough to get the kind of redundancy they have in airplanes. So what am I missing? I'm really curious.
- mikeash 12y ago