Propagation limitation for VOR-based navigation?

Propagation limitation for VOR-based navigation?

• A. Line of sight
• B. Ground wave
• C. Satellite-based
• D. Ionospheric reflection

Answer: (A)

VOR signals are in the VHF range, and these radio waves travel mainly by line of sight. Because they don’t bend well around the Earth's curvature or reflect reliably off the ionosphere, you need an unobstructed path between the VOR transmitter and the aircraft. The usable range is set by the geometry of the earth and the heights of the transmitting and receiving antennas—the higher you are, the farther you can receive the signal, up to the VOR’s practical limits. Terrain and obstacles can also block reception even at relatively short ranges. Ground waves apply to lower-frequency nav aids, ionospheric reflection applies to higher-frequency bands, and satellite-based navigation uses a different system altogether. So the key propagation constraint for VOR navigation is the line of sight.

VOR signals are in the VHF range, and these radio waves travel mainly by line of sight. Because they don’t bend well around the Earth's curvature or reflect reliably off the ionosphere, you need an unobstructed path between the VOR transmitter and the aircraft. The usable range is set by the geometry of the earth and the heights of the transmitting and receiving antennas—the higher you are, the farther you can receive the signal, up to the VOR’s practical limits. Terrain and obstacles can also block reception even at relatively short ranges. Ground waves apply to lower-frequency nav aids, ionospheric reflection applies to higher-frequency bands, and satellite-based navigation uses a different system altogether. So the key propagation constraint for VOR navigation is the line of sight.