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Communication
4.13.2.6 VHF and UHF
VHF and UHF radio waves propagate in straight lines from the transmitter.
There must be a “line of sight” (you must be able to see each other) between
the stations.
The maximum range depends on the transmitter output power and is usually
up to about 200 NM.
To be able to reach this far, the aircraft must be at a certain height above the
surface.
We have a formula for range that says:
Range in NM = √ x 1.23
Let's assume we are flying at 2500 feet. The range is: 50 * 1.23 = 61.5 NM
If we are flying at 900 feet, the range is: 30 * 1.23 = 37 NM
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4.13.3 Frequency bands on aircraft radio
A frequency band is a range of frequencies defined by a lower and an upper
limit. It refers to the range of radio frequencies used for transmitting signals in
various communication systems.
Frequency bands are used to organize and allocate radio frequencies for
different purposes.
COM: from 118,000 to
136,990 MHz
NAV: from 108,000 to
117,95 MHz
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 433
