應答機代碼列表

以下列表展示了在各個國家或地區用於特定目的之航空器應答機代碼和代碼範圍。傳統來說，每個國家都通過自己的方案分配轉發器代碼，不同國家的代碼幾乎沒有共同點。該列表由於歷史興趣而被保留。

飛行員通常需要將空中交通管制分配的代碼應用於特定的航班。有時，國家可能會指定在沒有分配代碼的情況下使用的通用代碼。此類通用代碼在該國的航空情報手冊或航行資料彙編中指定。對於國際民用航空組織（ICAO）定義的特定情況，有標準應答器代碼。

下列列表中，以紅色顯示的應答器代碼僅用於緊急情況，例如飛機劫持、無線電通信故障及機上發生緊急狀況等。

代碼	國家/地區	用途
0000	歐洲	Non-discrete mode A code; shall not be used.
	英國	Mode C or other SSR failure[1]
	美國	Should never be assigned.[2]
		Military intercept code.[3]
		Internal ARTCC subsets assigned by Enroute Safety and Operations Support. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
0021	德國	(VFR squawk code for airspace 5,000英尺（1,500公尺） and below prior to 15 March 2007 when replaced by the international 7000 code for VFR traffic.)[4]
0022	德國	(VFR squawk code for airspace above 5,000英尺（1,500公尺） – prior to 15 March 2007 when replaced by the international 7000 code for VFR traffic.)[4]
0025	德國	Parachute dropping in progress.[來源請求]
0033	英國	Parachute dropping in progress.[1]
0041–0057	比利時	Assigned for VFR traffic under Flight Information Services (BXL FIC).[來源請求]
0100	澳大利亞	Flights operating at aerodromes (in lieu of codes 1200, 2000 or 3000 when assigned by ATC or noted in the Enroute Supplement).
0100–0400	美國	Allocated to Service Area Operations for assignment for use by Terminal/CERAP/industry/unique purpose/experimental activities.[2]
0100–0700	美國	Non-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
	美國	Also for use in oceanic airspace unless another code is assigned by ATC.[2]
0500, 0600, 0700	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
1000	加拿大	Instrument Flight Rules (IFR) flight below 18,000 ft ASL when no other code has been assigned.[5]
	ICAO	Non-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.[6]
	美國	Used exclusively by ADS-B aircraft to inhibit mode 3A transmission.[2]
	美國	Non-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 (美國).[2]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
1100	美國	Non-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.[2]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
1200	澳大利亞	Civil VFR flights in class E or G airspace.[7]
	加拿大, 美國	Visual flight rules (VFR) flight standard squawk code used in North American airspace when no other has been assigned or is applicable.[5][2]
1201	美國	Assigned via FAR 93.95 for use by VFR aircraft in the immediate vicinity of LAX.[2]
	美國	(Visual flight rules (VFR) glider operations for gliders not in contact with ATC, through February 2012.)
1202	美國	Visual flight rules (VFR) glider operations for gliders not in contact with ATC; effective February 2012.[2]
	加拿大	Visual flight rules (VFR) glider operations for gliders not in contact with ATC; effective February 2017.[5][8]
1203–1272	美國	Discrete 1200 series codes unless otherwise allocated (for example, 1255), designated for DVFR aircraft and only assigned by a flight service station.[2]
1255	美國	Aircraft not in contact with an ATC facility while enroute to/from or within the designated fire fighting area(s).[2]
1273–1275	美國	Calibration Performance Monitoring Equipment (CPME) "Parrot" transponders.[2]
1276	美國	Air Defense Identification Zone (ADIZ) penetration when unable to establish communication with ATC or aeronautical facility.[2]
1277	美國	VFR aircraft which fly authorized SAR missions for the 美國AF or 美國CG while enroute to/from or within the designated search area.[2][9]
1300	美國	Non-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.[2]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
1400	加拿大	VFR flight above 12,500' ASL when no other code has been assigned.[5]
	日本	VFR flight above 10,000' MSL when no other code has been assigned.[來源請求]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
1500	美國	Non-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.[2]
	美國	External ARTCC subset. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
1600, 1700	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
2000	澳大利亞	Civil IFR flights in class G airspace.[7]
	加拿大	Uncontrolled IFR at or above 18,000 ft MSL.[5]
	ICAO countries	Code squawked when entering a secondary surveillance radar (SSR) area from a non-SSR area used as uncontrolled IFR flight squawk code.[6]
	EASA countries	Code that pilot shall set in the absence of ATS instructions related to code setting, unless when not receiving air traffic services.
	美國	Non-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.[2]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
2100	澳大利亞	Ground testing by aircraft maintenance staff.[7]
	美國	Non-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
	美國	Also for use in oceanic airspace unless another code is assigned by ATC.[2]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
2200, 2300, 2400	美國	Non-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
	美國	Also for use in oceanic airspace unless another code is assigned by ATC.[2]
	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
2500, 2600, 2700	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
3000	澳大利亞	Civil flights in classes A, C and D airspace, or IFR flights in class E airspace.[7]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
3100, 3200, 3300, 3400, 3500, 3600, 3700	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
4000	澳大利亞	Civil flights not involved in special operations or SAR, operating in class G airspace in excess of 15NM offshore.[7]
	美國	Aircraft on a VFR Military Training Route or requiring frequent or rapid changes in altitude.[10]
	美國	Non-discrete code assignments in accordance with FAA Order JO 7110.65, 5-2.
	美國	Also for use in oceanic airspace unless another code is assigned by ATC.[2]
	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
4100	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
4200, 4300	美國	Internal ARTCC subsets assigned by Enroute Safety and Operations Support. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
4400–4477	美國	Reserved for use by SR-71, YF-12, U-2, B-57, pressure suit flights, and aircraft operations above FL600.[2][10]
4401–4433	美國	Reserved in accordance with FAA Order JO 7110.67 (Federal Law Enforcement).[2]
4434–4437	美國	Weather reconnaissance, as appropriate.[2]
4440,4441	美國	Operations above FL600 for Lockheed/NASA from Moffett Field.[2]
4442–4446	美國	Operations above FL600 for Lockheed from Air Force Plant 42.[2]
4447–4452	美國	Operations above FL600 for SR-71/U-2 operations from Edwards AFB.[2]
4453	美國	High balloon operations: National Scientific Balloon Facility in Palestine, Texas; and other providers, some in international operations.[2]
4454–4465	美國	Air Force operations above FL600 as designated in FAA Order 7610.4.[2]
4466–4477	美國	Reserved in accordance with FAA Order JO 7110.67 (Federal Law Enforcement).[2]
4500, 4600, 4700	美國	Internal ARTCC subsets assigned by Enroute Safety and Operations Support. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
5000	澳大利亞	Aircraft flying on military operations.[7]
	美國, 加拿大	Reserved for use by NORAD.[2]
5061–5062, 5100, 5200	美國	Reserved for special use by Potomac TRACON.[2]
5100, 5200, 5300, 5500	美國	Internal ARTCC subsets assigned by Enroute Safety and Operations Support. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
5100–5300	美國	May be used by DOD aircraft beyond radar coverage but inside 美國 controlled airspace with coordination as appropriate with applicable Area Operations Directorate.[2]
5400	美國, 加拿大	Reserved for use by NORAD.[2]
5600, 5700	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
6000	澳大利亞	Military flights in class G airspace.[7]
	美國	External ARTCC subset. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
6100	美國, 加拿大	Reserved for use by NORAD.[2]
6200, 6300	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
6400	美國, 加拿大	Reserved for use by NORAD.[2]
6500, 6600, 6700	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
7000	ICAO	VFR standard squawk code when no other code has been assigned.[6]
	EASA countries	Code that pilot shall set when not receiving air traffic services, unless otherwise prescribed by the competent authority.[11]
	美國	External ARTCC subset. (Block of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
	澳大利亞	Unmanned aerial vehicle in all classes of airspace and when instructed to enable transponder.[7]
7001	France	Used in some countries to identify VFR traffic.
	英國	Sudden military climb out from low-level operations.[1]
7004	英國	Aerobatic and display code in some countries.[1]
7100, 7200, 7300	美國	External ARTCC subsets. (Blocks of discrete codes except that xx00 is used as a non-discrete code after all discrete codes are assigned.)[2]
	Switzerland	7100 in Switzerland for SAR (REGA).[12]
7400	美國, 英國, 澳大利亞	Unmanned aerial vehicle lost link.[13][14][15]
7500	ICAO	飛機被劫持[2][5]
7501–7577	美國	Reserved for use by Continental NORAD Region (CONR).[2]
7600	ICAO	飛機通訊故障[2][5]
7601–7607	美國	Reserved for special use by FAA.[2]
7610–7676	美國	External ARTCC subset (block of discrete codes).[2]
7615	澳大利亞	Civil flights engaged in littoral zone surveillance.[7]
7700	ICAO	飛機遭遇緊急情況[2][5]
7701–7707	美國	Reserved for special use by FAA.[2]
7710–7776	美國	External ARTCC subset (block of discrete codes).[2]
7777	美國, 德國, 比利時, 荷蘭	Non-discrete code used by fixed test transponders (RABMs) to check correctness of radar stations (BITE).
	美國	DOD interceptor aircraft on active air-defense missions and operating without ATC clearance in accordance with FAA Order 7610.4.[2][16]