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The problem with your proposal is several-fold: First, your hight from the ground changes very rapidly as you fly over terrain - you don't want to have to jot to the left every time you fly over a canyon. Second, it would require that you always take off and land pointed to the north, most airports would need to be reoriented, and you wouldn't want to land or take off when the winds are blowing from the south. Third, accurately measuring your distance from the ground is somewhat challenging, and the technology for accurately measuring the course you're tracking has only somewhat recently become available. Fourth, flying craft have maximum and minimum speeds, sometimes very close together, and maximum altitudes, so creating too tight an artificial coupling between speed and altitude can be very limiting.

In the US, there's a similar, but much more relaxed, system in use:

If you're more than 3000 feet above the ground, then the altitude above MSL in feet you should be at depends on whether you're flying under Instrument Flight Rules (IFR) or Visual Flight Rules (VFR) and your heading, as follows:

- For VFR with a magnetic heading 0-179: (1+2n) x 1000 + 500 (for integer n)

- For VFR with a magnetic heading 180-359: (2n) x 1000 + 500

- For IFR with a magnetic heading 0-179: (1+2n) x 1000 + 0

- For IFR with a magnetic heading 180-359: (2n) x 1000 + 0

Magnetic heading is trivial to measure, and under the specific rules used to determine MSL altitude, thats also really easy to measure (but might produce a large error relative to the correct answer, but a small error relative to other aircraft).

In addition, below 10,000 ft, the speed limit is generally 250kias or 200kias, depending on how close to the ground and other airports you are.


> There cannot be any major collisions only some slight grazes.

There's not necessarily much difference between those two.

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