High Frequency (HF)

High frequency (HF) refers to radio frequencies in the 3–30 MHz range. HF radio is used in aviation for long-range communication, particularly over oceans and in remote areas where VHF line-of-sight coverage does not extend. HF signals reflect off the ionosphere, enabling communication over thousands of nautical miles.

HF in Canadian Aviation

HF radio is used by aircraft operating on oceanic routes (North Atlantic, Pacific), in remote northern Canada, and in areas beyond VHF radar/radio coverage. Most commercial aircraft and many business jets are equipped with HF. GA aircraft rarely have HF — pilots flying to remote areas of Canada or across oceans must plan HF communications carefully.

HF vs. SATCOM

Satellite communication (SATCOM) has largely replaced HF for oceanic voice and datalink communications in commercial aviation. SATCOM is more reliable, clearer, and allows datalink (ACARS) messaging. However, HF remains a required backup system on many oceanic routes and is still used extensively in Canadian Arctic operations where SATCOM coverage may be limited.

Related Terms

See also: VHF, Arctic Control Area, ACARS.