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Radio and Interphone Communications — Aircraft Identification Last updated: 2017-07-10


When filing a flight plan, civil aircraft may use either their registration number or a three letter contraction followed by a flight number. In the RW, the total callsign cannot exceed seven characters; this limit is not enforced on vatsim, so you will often see callsigns of more than seven characters.

Callsign using registration number

U.S. registered civilian aircraft are all issued a registration number beginning with the letter "N."

Prefixes of “L” or “T” may be used prior to the "N" in the callsign. “L” indicates a Lifeguard flight; “T” indicates that it is an air taxi flight. As stated above, do not give priority to lifeguard flights on vatsim.

When the controller initiates communication with an aircraft, he should state the callsign, speaking each digit individually and using phonetic pronunciation for the letters (except when “L” is used as a prefix, see below for an example) . For example:

  • N303ZS - “November three zero three zulu sierra”
  • TN8734S - “Tango November eight seven three four sierra”
  • LN1TS - “Lifeguard November One Tango Sierra”

If a pilot calls and uses his aircraft type in his callsign, you may do the same. For example:

  • N303ZS - “Learjet three zero three zulu sierra”
  • N8734S - “Cessna eight seven three four sierra” or “Skylane eight seven three four sierra”
  • N1TS - “Bonanza one tango sierra” or “Beech one tango sierra”

Authorized Callsigns

The FAA will authorize callsigns for certain companies. On vatsim, there is no oversight of these callsigns and pilots may use them at their discretion. When communicating with these aircraft, state the callsign followed by the flight number in group form. For example:

  • UAL43 - “United forty three”
  • FDX102 - “FedEx one zero two”
  • SWA2358 - “Southwest twenty three fifty eight”

Zeros can be tricky in callsigns. If present they must be used in either group form or individual form, if needed. For example:

  • UAL001 - “United zero zero one”
  • SKW6040 - “Skywest sixty forty”
  • DAL1001 - “Delta ten zero one”
  • FDX500 - “FedEx five hundred”


The following abbreviations are used for military flights:

  • A – Air Force
  • C – Coast Guard
  • G – National Guard
  • R – Army
  • VM – Marine
  • VV – Navy

On vatsim, pilots don't always follow official guidance on callsign construction. The most basic military callsign, is the service identifier (see above) followed by a serial number. State the service name followed by the number. For example:

  • A4003 - “Air Force four zero zero three”
  • VVHK562 - “Navy Hotel Kilo five six two
  • VM800 - “Marine eight zero zero”

Military pilots may also choose a pronounceable word as a callsign followed by a number (in the RW, this combination cannot exceed seven characters, this limit is not enforced on vatsim). For example:

  • HAWK25 - “Hawk two five”
  • STRYK50 - “Strike five zero”

Foreign Callsigns

Foreign registered aircraft often have registration numbers composed of only letters. In these cases phonetic pronunciation is optional. For example:

  • CGFFC - “Charlie golf foxtrot foxtrot charlie” or “C-G-F-F-C”

For foreign air carriers, you may use separte digits in the callsign in place of group form, if that is used by the pilot. For example:

  • BAW23 - “Speedbird two three” or “Speedbird twenty three”

{Reference: FAAO 7110.65 2-3-5 & 2-4-20}

Abbreviated callsigns

After communications have been established, you may abbreviate the callsign of aircraft that do not use an authorized callsign. For example:

  • N8734S - “November three four sierra” or “Cessna three four sierra”
  • UAL1452 – must always be “United fourteen fifty two”

Heavy aircraft

Except for center controllers, heavy aircraft must always be identified by appending the term “heavy” to the end of the callsign. A pilot of a heavy aircraft should file “H/” prior to his aircraft type when filing a flight plan. The 7110.65 appendix A also identifies heavy aircraft. For example:

  • UAL43 (a Boeing 767) - “United forty three heavy”
  • AFR026 (an Airbus 340) - “Air France zero two six heavy”
  • N129P (a Boeing 747) - “November one two niner papa heavy” or “Boeing one two niner papa heavy” or "November two niner papa heavy" or "Boeing two niner papa heavy"
  • CGFFC (a DC10) - “Charlie golf foxtrot foxtrot charlie heavy” or “C-G-F-F-C heavy”