Definition

An aircraft call sign is a group of alphanumeric characters used to identify an aircraft in air-ground communications. (EUROCONTROL EATM Glossary of Terms)

Description

The rules governing the use of aircraft call signs are laid down in ICAO Annex 10: Aeronautical Communications, Volume II - Communication Procedures, Chapter 5. Relevant paragraphs are summarised below.

Three different types of aircraft call sign may be encountered (see table below), as follows: