Alphanumerics in callsigns

February, 27, 2020 by

In the real world, to reduce the likelihood of call sign confusion resulting from call sign similarity, airlines and ANSPs (air navigation service providers) sometimes will use alphanumeric call signs.

Alphanumeric call signs (EIN17A) replace the formerly purely numeric call signs (EIN17). They were introduced to reduce the likelihood of incidents like this happening, and are assigned to flights to in such a way as to maximize the differences between call signs and minimize the likelihood of confusion on frequency.

This is also why the callsign used on the passenger’s boarding pass may be different then the one used by ATC in communications. The commercial flight number, which most people commonly associate with a flight, includes the airline’s two digit IATA identifier and the airline-assigned flight number. The full call sign used by ATC includes the airline’s three digit ICAO identifier and the airline-assigned numeric or alphanumeric digits.

References: FlightRadar24

Kyle Boas is the Founder of the IFATC Education Group. He is an IFATC Supervisor and Infinite Flight Appeals team member. — More