This glossary is written for virtual airline and flight simulation use within Virtual Air Canada Airline. It is not intended as a real-world aviation reference.
SELCAL
Selective Calling System
SELCAL is an alerting system that allows ground stations to contact a specific aircraft without requiring the flight crew to monitor HF radio frequencies continuously. Each aircraft is assigned a unique four-letter SELCAL code made up of two pairs of audio tones. When a ground station transmits that code, the aircraft’s SELCAL decoder recognises the tones and triggers a chime and a light on the flight deck, alerting the crew that a call is waiting. This frees pilots from having to listen to the constant static and background noise common on HF frequencies during long-haul operations.
SELCAL is most valuable on oceanic and remote routes where VHF communication is unavailable and HF is the primary voice datalink. Before departure, crews verify their SELCAL code with their ATC or oceanic clearance provider and perform a SELCAL check shortly after reaching oceanic airspace. If the check fails, crews must monitor HF continuously as a backup. The system has been in use since the 1960s and remains a standard feature on long-haul widebody aircraft, though satellite-based communication systems such as SATCOM are increasingly used alongside it.