Callsign vs Flight Number: What's the Difference?

A flight number is the commercial identifier on your ticket (for example PK 300), while a callsign is the identifier used on the radio and by air traffic control (for example PIA300). They often look different because they use different airline codes.

Flight number

The flight number uses the airline’s two-letter IATA code plus digits: PK 300. It is what passengers, booking systems and airport screens use.

Callsign

The callsign uses the airline’s three-letter ICAO code plus numbers: PIA300. Some airlines use a different number in the callsign from the flight number, for example to avoid confusion with similar flights on the same frequency. Some use a spoken callsign too, such as “Pakistan 300”.

Why trackers use callsigns

ADS-B messages carry the callsign, not the ticket flight number. A tracker has to translate between them. This site does that for the airlines it knows: search PK 300 or PIA300 on the tracking page.

When they do not match

• Codeshare flights have several flight numbers but one callsign. See codeshare.
• Some airlines use unrelated or alphanumeric callsigns for certain flights.
• Charter, cargo and private flights may not have a flight number at all.

If you cannot find your flight, see how to track a flight without a flight number.

Learn the difference between the two code systems in IATA vs ICAO codes.

General information only, not legal or safety advice. Details change; check with your airline and the relevant authority. See our editorial policy.