It is observed on radio waves from high frequency to VHF through to microwaves[1] and, besides back-scattering, yields momentary propagation up to 800 kilometers (500 miles) even in mountainous terrain.
The advent of inexpensive SDR based and distributed real time flight tracking enabled precise scheduling, increasing feasibility.
Range and possible contact lengths are affected by the size of the plane, flight level and the approximate crossing time of the central part of the straight line between the two communicating stations.
[4] Both the onset and decay of the channel is rapid, so to improve success rate, a short contact procedure is used.
[6][7] Microwave access using high gain antennas needs to consider precise aiming that takes into account elevation angles as well.