[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.