Radio Horizon (line of sight)
Maximum line-of-sight range to the radio horizon for a VHF antenna, driven by antenna height and the curvature of the Earth.
Formula
Variables
Example
Antenna at 900 ft: d ≈ 1.23×√900 = 1.23×30 ≈ 37 nm
Did You Know?
VHF radios (VOR, ILS, comms) work only line-of-sight, which is why an aircraft at altitude can talk to a station hundreds of miles away while it vanishes the moment you land.
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