Sec.  87.107   Station identification.

   (a) Aircraft station. Identify by one of the following means:

   (1) Aircraft radio station call sign.

   (2) Assigned FCC control number (assigned to ultralight aircraft).

   (3) The type of aircraft followed by the characters of the registration
   marking (“N” number) of the aircraft, omitting the prefix letter “N”. When
   communication is initiated by a ground station, an aircraft station may use
   the  type  of  aircraft  followed  by the last three characters of the
   registration marking.

   (4) The FAA assigned radiotelephony designator of the aircraft operating
   organization followed by the flight identification number.

   (5) An aircraft identification approved by the FAA for use by aircraft
   stations participating in an organized flying activity of short duration.

   (b) Land and fixed stations. Identify by means of radio station call sign,
   its location, its assigned FAA identifier, the name of the city area or
   airport which it serves, or any additional identification required. An
   aeronautical enroute station which is part of a multistation network may
   also be identified by the location of its control point.

   (c) Survival craft station. Identify by transmitting a reference to its
   parent aircraft. No identification is required when distress signals are
   transmitted automatically. Transmissions other than distress or emergency
   signals, such as equipment testing or adjustment, must be identified by the
   call sign or by the registration marking of the parent aircraft followed by
   a single digit other than 0 or 1.

   (d) Exempted station. The following types of stations are exempted from the
   use of a call sign: Airborne weather radar, radio altimeter, air traffic
   control transponder, distance measuring equipment, collision avoidance
   equipment, racon, radio relay, radionavigation land test station (MTF), and
   automatically controlled aeronautical enroute stations.