For commercial aviation, call signs are decided by the airline's operations department in coordination with the International Civil Aviation Organization (ICAO). These are usually telephony designators like "Speedbird" (British Airways) or "Cactus" (the former US Airways). For general aviation, the call sign is simply the aircraft's registration (tail) number, assigned by the national aviation authority like the FAA. In the military, "tactical call signs" (like Maverick or Slayer) are traditionally bestowed upon pilots by their peers or squadron commanders during a "Naming Board" ceremony, often based on a humorous mistake or a personality trait. Once assigned, these names are used for radio communication to provide brevity and security during missions.