VHF propagation is amplitude modulated direct (line of sight) waves. The VHF waves are space waves (not sky waves). The reception of VHF transmission is normally influenced by the level of aircraft and terrain elevations.

VHF propagation characteristics are ideal for short-distance terrestrial communication and unlike high frequencies (HF), the ionosphere does not usually reflect VHF radio and thus transmissions are restricted to the local area. VHF is also less affected by atmospheric noise.

On the other hand, obstacles do impair the reception of VHF communications - the straight line joining the transmitter and the receiver must be relatively free of obstacles. Low level flight reduces greatly the range of reception, due to the presence of hills, mountains, bumps on the surface of the Earth and the roundness of the Earth itself. You may expect a solid reception when the aircraft is at high level in the vicinity of the ground station.

Note: Parked vehicles close to a transmitter may block the line of sight or reduce its range.