The term "squitter" refers to a random broadcast of data occurring either intentionally or in response to noise.


Mode-S transponders automatically send periodic burst transmissions called "squitters". These transmissions are self generated and are not in response to interrogations from a secondary surveillance radar (SSR) system. The information sent in these burst transmission serves several purposes including:

  • Airborne Collision Avoidance System (ACAS) - Squitter information includes aircraft location and vertical speed. This information is used by ACAS systems on other aircraft to identify potential conflicts.
  • Automatic Dependent Surveillance Broadcast (ADS-B) - An extended squitter is a message or series of messages which broadcast an aircraft's identification, GPS position, projected aircraft trajectory and navigation system status to allow controllers to accurately track the aircraft.

Related Articles


SKYbrary Partners:

Safety knowledge contributed by: