Regional Focus: Safety Significance and Implementation of Alphanumeric Call Signs

The possibility of miscommunication in aviation due to call sign confusion is real.

One contributing cause to call-sign confusion is the use of commercial flight numbers as call signs. There is a tendency for commercial flight numbers to be allocated consecutively with similar numbers, leading to similar sounding call signs. Instructions from air traffic control intended for one aircraft on heading, altitude, taxiing, runway entry and other clearances, or radio frequency changes, may be mistaken by another aircraft. This can lead to loss of separation between aircraft or runway incursion. There is also increased workload for pilots and air traffic controllers. 

Hub airports with hub carriers with many aircraft from the same airline operating in a small terminal airspace face a much higher probability of such a risk.   

One solution to the potential call sign confusion from the use of airline commercial flight numbers is to switch to the use of alphanumeric call signs.  This has been widely adopted in Europe and the Middle East.  However, this is not yet the case in the Asia Pacific.  ICAO, IATA, ACI, CANSO of the Asia Pacific region have taken up the cause to champion the wide adoption of alphanumeric call signs. 

To facilitate the change in call sign use, this webinar is designed to raise the awareness of the importance of alphanumeric call signs, share successful experience, address barriers to its implementation, and give insights to a smooth transition.  

The switch to alphanumeric call signs does not concern the airlines alone.  Airport systems and processes use commercial flight numbers in a wide range of interconnected systems, such as arrival and departure information on display boards and public websites.  There is a need for the translation of alphanumeric call signs into flight numbers in these systems, and vice versa.  There is a need for a systematic whole-of-aviation response. 

This webinar was for safety professionals, air navigation service providers, airport operators, airlines, and aviation regulators.