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