It's really surprising how many mid air collisions happen given the fact that there are 3 dimensions in which to avoid contact. I think that a significant percentage of these can be attributed to altitude fixation.

What is altitude fixation? It's when a pilot or air control chooses an easy or common altitude. Ex "I will fly at 12,000ft" instead of 11,800ft. Many people will pick the "easier" number. That could be a fatal mistake. Two aircraft at intersecting paths at 12,000ft is fatal. Two aircraft intersecting 200ft vertical separation is scary, but perfectly survivable.

Possible solutions:

- In flight random number generator. Key in 12,000 and it will spit up a close enough random number +/- 500ft. That way you avoid multiple pilots trying to be random at 12,000ft and they all happen to randomly pick 11,800 (there is no such thing as random if it comes from a human mind)

- Altitude broadcast. Have every aircraft carry a simple device. All it does it broadcast aircraft's height to other aircraft within 5 nautical miles of each other. Just make sure that their altitude never matches your altitude and you will be safe no matter where they are x,y coordinate-wise.

- Some kind of altitude offset system. Ex: aircraft registration num -> md5 sum -> decimal -> trim excess digits = altitude offset. So let's say G-KHMR has offset of +120 ft, the pilot will always fly at whatever height they normally should +120ft. Everyone would use the same calculation and the result would be more or less random flight paths. This gives new meaning to the term hash collission.

Important note, I realize that aviation needs precision. A random altitude will likely make any air traffic controller shiver - and rightfully so. Complete randomness is not the answer, but neither is complete precision. Complete precision can be fatal. How much randomness will save lives vs cause additional crashes could be determined by empirical studies. Do we need 200ft random altitude separation? Or is it 1000ft?
-- ixnaum, Aug 24 2015

[+] though I'm sure it's usually more complicated than aircraft colliding because they both chose the same easy to remember altitude.
-- FlyingToaster, Aug 24 2015


//more complicated than aircraft colliding because they both chose the same altitude

For sure, aircraft collide because crossing x,y coordinates and this idea nothing to stop that. This is a failsafe. Let's say air traffic screws up and lets two aircraft cross paths,now at least they won't hit. Think about this as an extra layer of safety, not a replacement.
-- ixnaum, Aug 24 2015


500 feet separation is the law - and it's ABSOLUTELY NOT random. Eastbound gets odd thousands; westbound is even thousands. If you're on VFR, you get 500 feet higher.

(These are US rules. If I understand correctly, the UK and some other countries use a quadrantal rule for altitude assignment.)

Random altitudes would only be slightly less deadly than just blowing up the planes on the ground.

(You may also want to find out about ADS-B and TCAS...)
-- lurch, Aug 24 2015


What about a convention where the direction of flight is associated with an altitude. North=1km, North east = 1.1km, etc.

This might also be useful for UAVs that will soon fill the skies delivering packages etc.
-- xaviergisz, Aug 24 2015


The trick, surely, is to re-introduce the serving of cocktails on the flight deck. What are the odds of two aircraft, both piloted by slightly squiffy pilots, both being at exactly their intended altitude at the same time, and in the same place?
-- MaxwellBuchanan, Aug 25 2015


I like xaviergisz idea.
-- ixnaum, Aug 25 2015


If we have cars which can drive autonomously then really how hard can it be to triangulate moving or stationary obstacles in the air and actively avoid them in case of human error? If one zigs the other has to zag.
What's the hold up? Does it infringe too much on missile avoidance patents or something?
-- 2 fries shy of a happy meal, Aug 27 2015


// What are the odds of two aircraft, both piloted by slightly squiffy pilots, both being at exactly their intended altitude at the same time, and in the same place? //

Higher than you might think. Some pilots (naming no names, but you know who you are*) tend to get argumentative and beligerent when drunk, and squabble over the controls. The resulting rollercoaster trajectory probably increases rather than reduces the chances of collision.

*And we're still waiting for you to return the gust lock. And our 'plane may be older than yours, but at least we look after it, and it has a windscreen clean of bug splash. Oh, and next time you make a crack like that in the Club bar, make sure your friends are there. If you have any, which we doubt.
-- 8th of 7, Aug 27 2015


Concorde had a couple of neat tricks for avoiding mid air collisions. Firstly, by simply inserting an additional 3.5 vertical miles between itself and the riff-raff traffic collisions were never a problem. Secondly, by travelling much much faster, the aircraft was in the air for less time. It's very difficult to suffer the uncomfortable consequences of a mid-air collision when you've been safely ensconced in an agreeable cocktail lounge for an hour.
-- bs0u0155, Aug 27 2015


Just allow pilots to install air-to-air missiles. The resulting arms race will make knowing where other planes are the least of their worries.
-- sninctown, Aug 27 2015


Don't the majority of mid-air collisions actually happen close to the airport, as part of departure or approach? Or as part of airshows. I'm sure there have been a few well away from the airport, but the only one I can think of was sightseeing over the grand canyon.
-- MechE, Aug 27 2015


That's true. You are most likely to die in airplane within 3 miles of your point of departure or your destination. So you should really consider flying somewhere else.
-- MaxwellBuchanan, Aug 27 2015


Again, I think they're dealing with this. If your destination is London, they very cleverly fly you miles away from it. Kent, Bishops Stortford or even Luton.
-- bs0u0155, Aug 28 2015



random, halfbakery