List of transponder codes


The following list shows specific aeronautical transponder codes, and ranges of codes, that have been used for specific purposes in various countries. Traditionally, each country has allocated transponder codes by their own scheme with little commonality across borders. The list is retained for historic interest.
Pilots are normally required to apply the code, allocated by air traffic control, to that specific flight. Occasionally, countries may specify generic codes to be used in the absence of an allocated code. Such generic codes are specified in that country's Aeronautical Information Manual or Aeronautical Information Publication. There also are standard transponder codes for defined situations defined by the International Civil Aviation Organization.
Transponder codes shown in this list in the color RED are for emergency use only such as an aircraft hijacking, radio communication failure or another type of emergency.
CodeCountriesAllocated use
0000EuropeNon-discrete mode A code; shall not be used.
0000UKMode C or other SSR failure
0000USShould never be assigned.
0000USMilitary intercept code.
0000USInternal ARTCC subsets assigned by Enroute Safety and Operations Support.
0021Germany
0021UKFixed-wing aircraft
0022Germany
0022UKHelicopter
0025GermanyParachute dropping in progress.
0033UKParachute dropping in progress.
0041–0057BelgiumAssigned for VFR traffic under Flight Information Services.
0100AustraliaFlights operating at aerodromes.
0100–0400USAllocated to Service Area Operations for assignment for use by Terminal/CERAP/industry/unique purpose/experimental activities.
0100–0700USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
0100–0700USAlso for use in oceanic airspace unless another code is assigned by ATC.
0500, 0600, 0700USExternal ARTCC subsets.
1000CanadaInstrument Flight Rules flight below 18,000 ft ASL when no other code has been assigned.
1000ICAONon-discrete mode A code reserved use in mode S radar/ADS-B environment where the aircraft identification will be used to correlate the flight plan instead of the mode A code.
1000USUsed exclusively by ADS-B aircraft to inhibit mode 3A transmission.
1000USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2. Also for use in oceanic airspace unless another code is assigned by ATC.
1000USExternal ARTCC subset.
1100USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2. Also for use in oceanic airspace unless another code is assigned by ATC.
1100USExternal ARTCC subset.
1200AustraliaCivil VFR flights in class E or G airspace.
1200Canada, USVisual flight rules flight standard squawk code used in North American airspace when no other has been assigned or is applicable.
1201USAssigned via FAR 93.95 for use by VFR aircraft in the immediate vicinity of LAX.
1201US
1202USVisual flight rules glider operations for gliders not in contact with ATC; effective February 2012.
1202CanadaVisual flight rules glider operations for gliders not in contact with ATC; effective February 2017.
1203–1272USDiscrete 1200 series codes unless otherwise allocated, designated for DVFR aircraft and only assigned by a flight service station.
1255USAircraft not in contact with an ATC facility while enroute to/from or within the designated fire fighting area.
1273–1275USCalibration Performance Monitoring Equipment "Parrot" transponders.
1276USAir Defense Identification Zone penetration when unable to establish communication with ATC or aeronautical facility.
1277USVFR aircraft which fly authorized SAR missions for the USAF or USCG while enroute to/from or within the designated search area.
1300USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2. Also for use in oceanic airspace, unless another code is assigned by ATC.
1300USExternal ARTCC subset.
1400CanadaVFR flight above 12,500' ASL when no other code has been assigned.
1400JapanVFR flight above 10,000' MSL when no other code has been assigned.
1400USExternal ARTCC subset.
1500USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2. Also for use in oceanic airspace unless another code is assigned by ATC.
1500USExternal ARTCC subset.
1600, 1700USExternal ARTCC subsets.
2000AustraliaCivil IFR flights in class G airspace.
2000CanadaUncontrolled IFR at or above 18,000 ft MSL.
2000ICAO countriesCode squawked when entering a secondary surveillance radar area from a non-SSR area used as uncontrolled IFR flight squawk code.
2000EASA countriesCode that pilot shall set in the absence of ATS instructions related to code setting, unless when not receiving air traffic services.
2000USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2. Also for use in oceanic airspace unless another code is assigned by ATC.
2000USExternal ARTCC subset.
2100AustraliaGround testing by aircraft maintenance staff.
2100USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
2100USAlso for use in oceanic airspace unless another code is assigned by ATC.
2100USExternal ARTCC subset.
2200, 2300, 2400USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
2200, 2300, 2400USAlso for use in oceanic airspace unless another code is assigned by ATC.
2200, 2300, 2400USExternal ARTCC subsets.
2500, 2600, 2700USExternal ARTCC subsets.
3000AustraliaCivil flights in classes A, C and D airspace, or IFR flights in class E airspace.
3000USExternal ARTCC subset.
3100, 3200, 3300,
3400, 3500, 3600,
3700		USExternal ARTCC subsets.
4000AustraliaCivil flights not involved in special operations or SAR, operating in class G airspace in excess of 15NM offshore.
4000USAircraft on a VFR Military Training Route or requiring frequent or rapid changes in altitude.
4000USNon-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
4000USAlso for use in oceanic airspace unless another code is assigned by ATC.
4000USExternal ARTCC subsets.
4100USExternal ARTCC subsets.
4200, 4300USInternal ARTCC subsets assigned by Enroute Safety and Operations Support.
4400–4477USReserved for use by SR-71, YF-12, U-2, B-57, pressure suit flights, and aircraft operations above FL600.
4401–4433USReserved in accordance with FAA Order JO 7110.67.
4434–4437USWeather reconnaissance, as appropriate.
4440,4441USOperations above FL600 for Lockheed/NASA from Moffett Field.
4442–4446USOperations above FL600 for Lockheed from Air Force Plant 42.
4447–4452USOperations above FL600 for SR-71/U-2 operations from Edwards AFB.
4453USHigh balloon operations: National Scientific Balloon Facility in Palestine, Texas; and other providers, some in international operations.
4454–4465USAir Force operations above FL600 as designated in FAA Order 7610.4.
4466–4477USReserved in accordance with FAA Order JO 7110.67.
4500, 4600, 4700USInternal ARTCC subsets assigned by Enroute Safety and Operations Support.
5000AustraliaAircraft flying on military operations.
5000US, CanadaReserved for use by NORAD.
5061, 5062, 5100,
5200		USReserved for special use by Potomac TRACON.
5100, 5200, 5300,
5500		USInternal ARTCC subsets assigned by Enroute Safety and Operations Support.
5100–5300USMay be used by DOD aircraft beyond radar coverage but inside US controlled airspace with coordination as appropriate with applicable Area Operations Directorate.
5400US, CanadaReserved for use by NORAD.
5600, 5700USExternal ARTCC subsets.
6000AustraliaMilitary flights in class G airspace.
6000USExternal ARTCC subset.
6100US, CanadaReserved for use by NORAD.
6200, 6300USExternal ARTCC subsets.
6400US, CanadaReserved for use by NORAD.
6500, 6600, 6700USExternal ARTCC subsets.
7000ICAOVFR standard squawk code when no other code has been assigned.
7000EASA countriesCode that pilot shall set when not receiving air traffic services, unless otherwise prescribed by the competent authority.
7000USExternal ARTCC subset.
7000AustraliaUnmanned aerial vehicle in all classes of airspace and when instructed to enable transponder.
7001FranceUsed in some countries to identify VFR traffic.
7001UKSudden military climb out from low-level operations.
7004UKAerobatic and display code in some countries.
7100, 7200, 7300USExternal ARTCC subsets.
7100, 7200, 7300Switzerland7100 in Switzerland for SAR.
7400US, UK, AustraliaUnmanned aerial vehicle lost link.
7500ICAOAircraft hijacking.
7501–7577USReserved for use by Continental NORAD Region.
7600ICAORadio failure.
7601EuropeRadio failure, IFR flight in visual meteorological conditions, effective May 1st 2025.
7601–7607USReserved for special use by FAA.
7610–7676USExternal ARTCC subset.
7615AustraliaCivil flights engaged in littoral zone surveillance.
7700ICAOEmergency.
7701–7707USReserved for special use by FAA.
7710–7776USExternal ARTCC subset.
7776EuropeThe Mode A code 7776 is assigned as a test code by the ORCAM Users Group, specifically for the testing of transponders.
7777US, Germany,
UK, Belgium,
Netherlands		Non-discrete code used by fixed test transponders to check correctness of radar stations.
7777USDOD interceptor aircraft on active air-defense missions and operating without ATC clearance in accordance with FAA Order 7610.4.