[lucasjung]

I fly for a living, and I currently work in developmental flight test. One of the programs I am working on is a UAV.

It's going to be a very, very long time before we see autonomous airliners. I'll talk about specific technical hurdles, but I think the biggest issue is psychological: it's one thing to entrust a bunch of freight to an autonomous vehicle, another thing entirely to entrust dozens of living, breathing human beings to such (the article discusses this, including the concept of "shared fate"). I am confident that autonomous airliners will only come into service when autonomous aircraft technology reaches a point where the computers are able to handle every aspect of flight safety better than humans. Right now they can already do some of those things better than humans, and those tasks have already largely been shed by human pilots and entrusted to their computers. I think there will be a gradual transition as the computers are able to take on more and more of the tasks. The article also mentions how this process is already causing basic aviation skills to atrophy in pilots who leave too much to the computers. I think this is a very real problem, and I think it was a major contributor to the Air France flight 447 crash. Prudent pilots do more manual flying than is strictly necessary because that's the only way to maintain proficiency. If this problem becomes severe enough, expect to see the FAA establish more granular proficiency requirements.

The author talks a lot about how much the military is using UAVs, and seems to think that this is a good model for civilian applications. It isn't. The military has an entirely different set of risk considerations than civil aviation. Take the example of medivac UAVs: a medivac UAV will almost certainly have a higher mishap rate than a manned medivac helo, which would be completely unacceptable for civilian purposes. However, for the military that increased mishap risk is more than offset by the risks of putting an entire human crew into harm's way just to medivac a single wounded soldier.

Military UAVs currently in use generally have much higher mishap rates than their manned counterparts, but the military tolerates this because aicrew don't die in UAV mishaps, and UAVs are generally less expensive to replace than manned vehicles. Part of the reason for this is that features designed to prevent or mitigate mishaps cost money, and it is often cheaper to leave many of them out and accept the higher mishap rate, especially when no human crew is involved. However, part of it is that autonomous systems still just aren't as good at flying safely. For the military, the benefits outweigh the costs, but I really can't see a for-profit corporation reachig the same conclusion.

>Northrop Grumman has built some sense-and-avoid savvy into the unmanned helicopters and other UAVs it's developing for the U.S. Navy.

I happen to be intimitely familiar with one such system, and somewhat familiar with another. This sentence is utter BS. I can only assume that the author was fed a line by an NGC PR-type and took it at face value. A more honest way to say it would be:

Northrop Grumman is trying to incorporate limited sense-and-avoid capabilities into the unmanned helicopters and other UAVs it's developing for the U.S. Navy.

Moreover, FAA has a requirement for "see and avoid," not "sense and avoid." The military is trying hard to sell them on the idea that it should be "sense and avoid," of which "see and avoid" would be just a subset, but so far the FAA has remained deeply skeptical. The FAA is right to be conservative about this change: none of the currently proposed systems would be as effective at collision avoidance as the Mark I Eyeball, and thus far the systems I am aware of (to which the quote from the article was referring) are still a very long way from working properly. This seems to me like the kind of technical problem that eventually can be overcome, but it's going to take a lot of work to make that happen.

Because "see and avoid" is so critical to safety of flight, and because UAVs can't currently do it, the FAA does not allow UAVs to operate in its airspace, with some tightly restricted exceptions for military and law enforcement UAVs. I doubt very highly if they would make similar exceptions for civilian purposes, and even if they did, the restrictions involved are so limiting that there aren't many viable applications.

[JoeAltmaier]

In just a couple of years the DARPA challenge yielded cars that can drive themselves in complex urban environments.

I imagine with sufficient smart people working on it, flying airplanes in relatively uncluttered sky would yield results faster.

As for see-and-avoid, perhaps it works for obstacles on the ground, but other aircraft are moving so fast, is it really feasible to eyeball them before they are on you? Perhaps in pursuit, but at any significant angle they flash past at hundreds of miles an hour. Only radar etc has a chance of identifying/avoiding at those speeds. <Edit: spelling>

[brlewis]

Commercial airliners, last I checked, suffered one mishap per 1.5 million flights. Human automobile drivers set a much lower standard to beat.

[JoeAltmaier]

Sure; but the flight environment is trivial in comparison with urban traffic. Even so, with concerted effort the progress was phenomenal.

[lucasjung]

>the flight environment is trivial in comparison with urban traffic.

Having experienced plenty of both, I can tell you that this is utterly false.

[marshallp]

Says the human. To a computer driving is much more difficult than flying.

You could equally say adding up big numbers is much harder for you than walking across the street. To a computer the former is trivial, the latter no walking robot has yet done.

[lucasjung]

As I've mentioned elsewhere, I'm directly involved in the test and evaluation of one of the current attempts at "sense and avoid" technology. It is a long way from being safe for fully autonomous use. It is my understanding that the DARPA autonomous land vehicle contest required autonomous collision avoidance, and that more than one of the entrants did so effectively. Their budgets were a pittance compared to what is being spent on "sense and avoid" for UAVs, and yet they had much greater success. That tells me that urban traffic avoidance is easier for computers than air traffic avoidance.

I think that two big reasons for this are probably:

1: For land vehicles, simply stopping in place is almost always an effective collision avoidance tactic (unless the other vehicle is deliberately seeking a collision). This simple solution is not available to airplanes.

2: Tracking objects thar are moving in three dimensions with a sensor that is also moving in three dimensions is an immensely more complex problem than tracking objects that are constrained to move on a fixed surface in two dimensions with a sensor that is also constrained to move on a fixed surface in two dimensions.

[zerostar07]

I think a large part of that low mishap rate is exactly due to automation.

[lucasjung]

>In just a couple of years the DARPA challenge yielded cars that can drive themselves in complex urban environments.

I imagine with sufficient smart people working on it, flying airplanes in relatively uncluttered sky would yield results faster.

As I mentioned, many of the tasks of flying airplanes have been successfully automated. However, there are significant complexities that pilots must deal with that don't apply to cars, and most of those still require human intervention, especially in-flight emergencies. If your car engine quits, you pull over to the shoulder, turn on your hazard lights, and call AAA. If your aircraft engine quits, the response is much more complex. If the power steering on your car quits, you do pretty much the same thing as described above. If your flight controls malfunction in an airplane, the response is much more complex. If your car catches on fire, you do the same as above, plus get out. If your airplane catches on fire, you've got a much bigger problem. I could go on, but I think that gets the idea across.

Also, the sky is not "relatively uncluttered." There are a lot of airplanes flying at any given moment, and most of them are concentrated onto airways. It gets even worse in the terminal area: lots and lots of planes coming and going to and from many different directions, all in a very small piece of sky.

>As for see-and-avoid, perhaps it works for obstacles on the ground, but other aircraft are moving so fast, is it really feasile to eyeball them before they are on you? Perhaps in pursuit, but at any significant angle they flash past at hundreds of miles an hour. Only radar etc has a chance of identifying/avoiding at those speeds.

I am alive today because, on countless occasions, I and my fellow aviators have looked outside, seen another aircraft, and maneuvered to avoid a potential collision. I think that you really don't have an accurate mental image of how this works, so I'll try to explain a little bit:

Consider two airliners cruising at 424 kts each, one heading due West, the other due North. The rate of closure is 600 kts. Depending on the atmospheric conditions, they will be visible to each other at about 10 nautical miles, which gives them an entire minute to spot each other and maneuver to avoid a collision. Even if it's two sueprsonic fighters flying right at each other at 600 kts each, they still have thirty seconds to spot each other. A much more realistic scenario would involve two aircraft in the terminal area, where they would be moving much more slowly, giving them much more time to see each other and respond.

I think the most dangerous situations are where two aircraft are on headings that are different by less than forty-five degrees: they are basically next to each other, closing from each other's sides where they are less likely to be spotted. The rate of closure is probably very low, but that's more than made up for by the awkward situation in regards to field of view from many cockpits.

[yread]

> If your airplane catches on fire

I think that unmanned plane has actually a much better chance of surviving fire, it could have an inert atmosphere, or it could be unpressurized so fires would be much less frequent. Also fires happen mostly on freight planes (lately UPS and Asiana) and freight planes would be probably easier to certify for unmanned flying than passenger planes.

> I am alive today because, on countless occasions, I and my fellow aviators have looked outside, seen another aircraft, and maneuvered to avoid a potential collision.

Isn't this what Traffic collision avoidance system (TCAS) is for? The pilots already have to do as they are told by TCAS (after the collision over Switzerland). Surely managing traffic of obedient agents with known limits of performance isn't that hard - if all the planes were unmanned there wouldn't be problems

However, the points that you mentioned about other emergencies and passenger traffic still stand.

[lucasjung]

>it could have an inert atmosphere

This would be very costly to implement, and probably very heavy. That being said, inert gases are used in places where arcing is likely (e.g. radar waveguides).

>or it could be unpressurized so fires would be much less frequent

I really don't think this would have a significant impact on the frequency of fires. Plus, a lot of avionics need particular environmental conditions, in some cases including pressurization.

>Also fires happen mostly on freight planes

High-power electronics, such as military radars, also pose an increased risk of fire.

>freight planes would be probably easier to certify for unmanned flying than passenger planes.

If you only cared about the contents of the plane, this would be true. But what happens when a flaming ball of wreckage that used to be an unmanned freight plane plows into a suburban neighborhood, a school, or a downtown skyscraper?

>Isn't this what Traffic collision avoidance system (TCAS) is for? The pilots already have to do as they are told by TCAS (after the collision over Switzerland).

TCAS isn't all it's cracked up to be. First of all, it only works if the other plane has a transponder (there are still plenty of light civil aircraft out there with no transponders). Second, there are different versions out there with different levels of accuracy. The older kind are not very accurate at all, and basically serve only to give the pilot a general idea of where to look in order to spot the traffic and avoid the collision the old-fashioned way. The more accurate kind only works if both aircraft involved have the necessary equipment.

As for the collision over Switzerland, the reason for that rule is that the collision happened in part because TCAS and ATC gave conflicting instructions: one told plane A to go up and plane B to go down, the other told plane A to go down and plane B to go up. One crew did what TCAS said, the other did what ATC said, and they both ended up descending. So the reason for this rule isn't that TCAS is a magical panacea for midairs, but rather a way to consistently resolve any future such conflicts between TCAS and ATC.

>Surely managing traffic of obedient agents with known limits of performance isn't that hard - if all the planes were unmanned there wouldn't be problems

If all the planes were unmanned, then managing traffic would be much easier, but that still leaves other issues, like where a plane ends up when it malfunctions and crashes. It would also require a wholesale changeover that simply isn't plausible.

[rohit89]

> TCAS isn't all it's cracked up to be. First of all, it only works if the other plane has a transponder (there are still plenty of light civil aircraft out there with no transponders).

Why hasn't it been made mandatory that all aircrafts should have a standardized transponder ? It scares me a bit that, at the end of the day, we rely on pilots avoiding collisions by sight.

[lucasjung]

>Why hasn't it been made mandatory that all aircrafts should have a standardized transponder ?

In some parts of the world, it may be. For example, I don't know if Europe allows for aircraft without transponders. Even in the U.S. you must have a transponder to enter certain types of airspace (e.g. the airspace around major airports). As far as I know, no matter where you are in the world, you must have a transponder to fly IFR.

Installing a transponder is a non-trivial expense, especially in older aircraft (which are the aircraft most likely to not have transponders). For a lot of small aircraft in the U.S. this would represent an unnecessary burden on the owners. For example, crop dusters: they typically fly around low and slow in areas with very little traffic, under day VFR conditions, so they have no need to interact with ATC and therefore no real use for a transponder.

>It scares me a bit that, at the end of the day, we rely on pilots avoiding collisions by sight.

We don't rely solely on this: we have transponders (with TCAS in some cases), ATC radar, and (in some cases) airborne radar. All of these tools help us to avoid collisions. Unfortunately, none of them are 100% effective, and in most of the situations where they all fail, the good old Mark I Eyeball usually saves the day. See-and-avoid isn't perfect, either (if it was, we'd never have midairs), but it is still the most effective tool available for avoiding an impending collision.

[spitfire]

Because they cost an arm and a leg for small aircraft. Think $20K.

Unfortunately regulations and liability costs make anything in aviation expensive. So most small planes are running around without tcas.

[marshallp]

Your objections are about things that a human can't do much about either, or if they could, a computer could do just as well or better.

(If your plane engine quits - what would a human do? whatever it is, a computer could be programmed to as well. Near collisions - a constantly vigilant computer vision system watching out the window is more likely to avoid collision than a pilot with 30 seconds of reaction time.)

[lucasjung]

>If your plane engine quits - what would a human do?

This depends on a lot of factors. Some of them are things that a computer can probably be programmed to consider properly (e.g. specific cause of failure). Other factors require judgment, such as your more general situation: depending on where you are and what else is going wrong, you might chose to land the airplane at the nearest appropriate airfield, or you might choose to continue on to an airfield farther away where you can get better support while attempting to restart the failed engine on your way there, or you might decide that you have to get it on the ground right now, and that empty farmer's field over there looks good enough.

In case of more catastrophic failures like fire, computers become even more problematic because the sensors they depend on for inputs can be damaged or destroyed, leaving them with insufficient information to act properly.

>Near collisions - a constantly vigilant computer vision system watching out the window is more likely to avoid collision than a pilot with 30 seconds of reaction time.

People with a lot of money and resources have been trying to develop a fully autonomous system for avoiding impending collisions. They will almost certainly eventually succeed, but so far they haven't even come close to being as visual scan by human pilots.

[EDIT: resolved ambiguous use of "field.")

[marshallp]

A billion dollars was spent by the eu in the 80s on self-driving cars. They didn't completely succeed. It looked like noone would succeed for 30 years. And yet, bang, when the competition's opened up, a couple of guys from stanford do it.

I believe the technology to solve the problem is out there, it's just a matter of the right people trying at it.

Computer vision is close to being solved. Look at kinect, kinect 2/google goggles. People inside google/microsoft are racing at this. I'm sorry, i have to disagree with your pessimistic attitude on this.

With regard to fire - fire can kill human pilots too. With sensors, you can create a multiply redundant system - put in 20 extra sensors. With humans it's not possible.

[lucasjung]

Nothing you say addresses my broader point that there are currently too many situations in aviation where the complexity of the decisions involved exceeds our current capacity for automation.

A billion dollars was spent by the eu in the 80s on self-driving cars. They didn't completely succeed. It looked like noone would succeed for 30 years. And yet, bang, when the competition's opened up, a couple of guys from stanford do it. I believe the technology to solve the problem is out there, it's just a matter of the right people trying at it.

If they tried in the '80s and the guys from Stanford did it in the 2000's, then it was almost 30 years before anyone succeeded. I think that success had a lot more to do with technology maturing over time than it did with "the right people trying at it."

>Computer vision is close to being solved. Look at kinect, kinect 2/google goggles. People inside google/microsoft are racing at this.

This really depends on what you mean by "solved." Kinect is a hell of a long way from what you would need to avoid collisions in a 3D space. Kinect basically just has to deal with the outlines of objects at a relatively narrow set of distances. When your sensor is moving in three dimensions and you are trying to track an object that is also moving in three dimensions it gets a heck of a lot harder, even if you are using radar (which gives you range). If you're trying to figure out range based on the apparent size of an object of unknown actual size, it gets even harder.

>I'm sorry, i have to disagree with your pessimistic attitude on this.

I'm actually quite optimistic that it will happen, just not for many years yet.

>With regard to fire - fire can kill human pilots too. With sensors, you can create a multiply redundant system - put in 20 extra sensors. With humans it's not possible.

If your engine is out on a wing and it catches fire, the fire sensors will tell you so, and shortly thereafter they will most likely be destroyed and tell you nothing further. An engine on fire out on the wing is not going to burn up the pilot. The pilot can look out the window and quickly and easily assess the condition of the engine and the wing: did it burn out, or is it raging out of control, or maybe there are subtle signs that indicate something in-between? Maybe with enough fire sensors scattered all over the plane a computer could make a similar assessment, but you're talking about a lot of extra money and weight, and you still have the problem that your sensors are going to burn up shortly after going off and then you have no idea if the fire has gone away or if it has just stopped spreading. Someday maybe you can give the computer a camera to "look" at the wing to make the same kind of assessment that a human pilot can make, but that is a very long way off.