When I read the Bob Shaws book "Vertigo" in 1979 about personal flight-vest, I designed navigation rules of all aerial vehicles big and small. It is as follows:
If the vehicle is X meters from the ground, the only allowed direction is (X mod 360) degrees, and the only possible speed is X/10 meter per second. Hence the vehicle moves along helical path until it reaches the only height where the desired speed and direction is allowed. There cannot be any major collisions only some slight grazes.
Ingenious, nicht wahr?
The problem of what is the "ground level" and how passenger jets behave is beyond this brief introduction.
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.
Also:
> There cannot be any major collisions only some slight grazes.
There's not necessarily much difference between those two.
Pretty ingenious, might steal this idea at some point in the future.
So the idea is that, in a given XY plane, all equilibrium flows are at the same direction and speed. You can never go exactly 26 m/s due north, but you can get close enough. By definition, vehicles in the equilibrium state can't hit other vehicles on the same XY plane, and vehicles in equilibrium at slightly displaced XY planes will only hit others at arbitrarily small angles. So far, so good.
Going up and down is simultaneously handled in the XY plane, because at a given height, a vehicle's direction of travel is tangent to the helix and going along with the flows. Also good.
There needs to be a strict speed limit on vertical speed. A vehicle hitting you from underneath or above at 30 m/s is pretty terrible.
A representative table for the lazy
Height Direction Speed (m/s) Speed (mph freedom units)
0 N 0 0
90 E 9 20.1
180 S 18 40.3
270 W 27 60.4
360 N 36 80.5
Though I might make the coils of the helix a bit tighter, so you can get within 5 mph of your desired speed at whichever direction you want to go.
Other problems:
- It may not be possible to arrange landing areas in the desired direction
- Vehicles may not be able to make sufficiently tight turns
- Fixed-wing vehicles cover quite a large vertical distance, especially when rolling as they turn due to wingspans. There's plenty of room for converging paths, and your rules may not allow enough leniency to avoid such paths. A "slight graze" that takes off half a wing is not acceptable.
- Parallel lines converge on the surface of the world. Two planes flying due north (X is a multiple of 360) may collide at or near the poles.
If the vehicle is X meters from the ground, the only allowed direction is (X mod 360) degrees, and the only possible speed is X/10 meter per second. Hence the vehicle moves along helical path until it reaches the only height where the desired speed and direction is allowed. There cannot be any major collisions only some slight grazes.
Ingenious, nicht wahr?
The problem of what is the "ground level" and how passenger jets behave is beyond this brief introduction.