Aircraft identifiers
What Is an Aircraft Squawk Code?
A squawk code is a Mode A transponder code used in air traffic surveillance. It is not the same thing as an airline flight number, aircraft registration, or ICAO aircraft address.
By TransitSatellite · Reviewed October 20, 2026
The transponder carries surveillance information
Aircraft transponders respond to surveillance systems and can transmit coded information. ADS-B broadcasts can include the Mode A code along with other aircraft data.
A squawk code is not a permanent aircraft identity
A transponder code can be assigned for an operation and should not be treated as a permanent identifier for one aircraft. Public trackers may display it as one field among several identifiers.
Flight ID and aircraft address are different fields
FAA guidance distinguishes the Mode A code from the aircraft’s unique ICAO address and from the Flight ID, which can correspond to a registration or operator call sign/flight number depending on the operation.
Common questions
Is a squawk code the same as a flight number?
No. A flight number identifies an airline service, while a squawk code is a transponder code used for surveillance and air traffic control purposes.
Can a public flight tracker show a squawk code?
Some services display transponder-related fields when those data are available and permitted by the provider.
Sources
Flight tracker search
Start with a flight number or route and open the current tracking source.
Search flightsTransportation globe
See the airport layer on the existing TransitSatellite 3D globe.
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