Squawk Codes — memorise
General (ICAO)
ICAO Annex 10 Vol IV + PANS-OPS Doc 8168 define the international standard squawk codes.
Transponder modes
The standard SSR transponder modes in aviation are Mode A for aircraft identification, Mode C for altitude reporting, and Mode S for enhanced selective surveillance and data exchange:
| Mode | Function |
|---|---|
| Mode A | 4-digit squawk code (identification) |
| Mode C | Altitude (pressure altitude) |
| Mode S | Selective addressing + data |
A transponder with the ability to send the current pressure level is a mode C or S transponder.
Standard emergency codes (memorise!)
| Code | Meaning |
|---|---|
| 7500 | Hi-jacking / unlawful interference — "the transponder code in case of a hi-jacking is 7500" |
| 7600 | Radio failure — "the transponder code in case of radio failure is 7600" |
| 7700 | General emergency — "in case of an emergency the transponder should be set to 7700" |
Standard conspicuity codes
| Code | Meaning | Region |
|---|---|---|
| 7000 | VFR standard | Europe |
| 1200 | VFR standard | USA |
| 2000 | IFR standard without ATC assignment | worldwide |
Squawk 7000 in EU
Transponder code A/C 7000 has to be set by own accord by powered aircraft on VFR flights in airspace E above 5000 ft AMSL or above 3500 ft AGL, whichever is higher (see airspace classes §5.3).
Radio failure without request
Transponder code 7600 should be set without any request in case of radio failure.
Europe (EASA / EU)
SERA.13005 Use of SSR Transponder: squawk codes per ICAO + EU specifics.
Germany (national)
DFS AIP Germany ENR 1.6 — standard 7000 for VFR above 5000 ft AMSL.