Radio Call Sign

Aviation

In most countries, the aircraft call sign or "tail number"/"tail letters" (also known as registration marks) are linked to the international radio call sign allocation table and follow a convention that aircraft radio stations (and, by extension, the aircraft itself) receive call signs consisting of five letters. For example, all British civil aircraft have a five-letter registration beginning with the letter G, which can also serve for a call sign. Canadian aircraft have a call sign beginning with C–F or C–G, such as C–FABC. wing-in-ground-effect vehicles and hovercraft in Canada are eligible to receive C–Hxxx call signs, and ultralight aircraft receive C-Ixxx call signs. In days gone by, even American aircraft used five-letter call signs, such as KH–ABC, but they were replaced prior to World War II by the current American system of civilian aircraft call signs (see below). One exception to the parallelism between registration and call sign is ultralight airplanes in France, who are not obliged to carry a radio and indeed often don't.