Hertz (Hz)
Hertz (Hz) is the unit of frequency, defined as one cycle per second. In aviation communications and navigation, frequencies are expressed in kilohertz (kHz, thousands of Hz) or megahertz (MHz, millions of Hz). VHF communications operate in the 118–137 MHz range; NDB navigation operates in the 190–1750 kHz range.
Aviation Frequency Bands
- VHF (30–300 MHz): ATC communications (118–137 MHz), VOR navigation (108–117.95 MHz), ILS localizer (108–111.95 MHz), ATIS, UNICOM
- UHF (300 MHz–3 GHz): DME (962–1213 MHz), ILS glide slope (329.15–335 MHz), military communications
- HF (3–30 MHz): Long-range oceanic communications; used where VHF line-of-sight is insufficient
- LF/MF (30 kHz–3 MHz): NDB navigation (190–1750 kHz)