This page is for study and reference purposes only. In an actual emergency, follow your aircraft's Emergency Checklist (QRH/AFM), training, and ATC instructions. There is no substitute for proper emergency training with a certified instructor.
Emergency Procedures
Standard aviation emergency phraseology, squawk codes, and procedures — per ICAO Annex 2 and Annex 10.
Last reviewed: March 2026
Emergency vs Urgency
Distress
A condition of being threatened by serious and/or imminent danger requiring immediate assistance.
- Engine failure
- Fire on board
- Medical emergency requiring immediate landing
- Structural damage affecting flight safety
- Fuel exhaustion / imminent fuel emergency
Urgency
A condition concerning the safety of an aircraft or its occupants but not requiring immediate assistance.
- Medical case requiring priority handling
- Single engine failure on multi-engine aircraft
- Low fuel (not yet emergency)
- Navigation problems
- Technical fault (non-critical)
MAYDAY Call Format
In a real emergency, aviate first — maintain aircraft control. Then navigate and communicate. Do not allow radio calls to distract from flying the aircraft.
A MAYDAY call in aviation is the international radio distress signal indicating a life-threatening emergency requiring immediate assistance. Derived from the French m'aidez (help me), it is transmitted three times consecutively and takes absolute priority over all other radio communications per ICAO Annex 10.
Always transmit MAYDAY (or PAN PAN) on the frequency you are currently working. If no response, try 121.5 MHz (international distress frequency, monitored 24/7 by ATC and aircraft).
Mnemonic: NITS or ATIMNE — A=Aircraft callsign, T=Type, I=Intentions, M=Meteorological/altitude, N=Nature of emergency, E=Endurance/POB. Adapt to situation — in a real emergency, the most important things are: who you are, where you are, what's wrong, what you want.
Example MAYDAY Call
PAN PAN Call Format
Example — Fuel Urgency
Emergency Transponder Codes
For a complete guide to all transponder codes (including standard and regional codes), see our Squawk Codes Reference.
| Code | Name | Use | Action Required |
|---|---|---|---|
| 7700 | General Emergency | Distress — MAYDAY | Set when declaring MAYDAY. Retains last set code for 30 seconds when switched to avoid false alerts. |
| 7600 | Radio Failure (NORDO) | Lost communications | Set when all communication attempts have failed. Maintain last clearance, then follow lost comms procedures. |
| 7500 | Hijack / Unlawful Interference | Aircraft under threat | Set covertly if possible. ATC will acknowledge without mentioning the code over radio. |
| 7000 | VFR (Europe) | Standard European VFR | Default squawk for uncontrolled VFR in much of Europe. |
| 1200 | VFR (USA) | Standard US VFR | Default squawk for uncontrolled VFR in the USA. |
| 2000 | No ATC contact | Entering controlled airspace without clearance | Squawk when entering controlled airspace without prior ATC contact. |
Lost Communications Procedures (7600)
Note: Radio failure procedures vary by country and airspace. The following is a general guide based on ICAO Doc 4444. Always refer to the national AIP and your local authority procedures.
- 1Attempt re-establishment of communication
- Try different frequencies (last assigned, previous freq, 121.5 MHz)
- Try different radio (if equipped)
- Check all connections, volume, squelch
- 2Set transponder to 7600
This alerts ATC to your situation automatically and identifies you as NORDO on radar.
- 3If in VMC (Visual Meteorological Conditions)
- Continue flight in VMC
- Land at nearest suitable aerodrome
- Report arrival to ATC as soon as possible
- 4If in IMC (Instrument Meteorological Conditions)
- Continue on the last assigned route/level for 7 minutes (or to the next reporting point, whichever is later)
- Then proceed according to the filed flight plan
- Descend to expected approach level at the last cleared/expected/filed level
- Begin approach procedure at the Expected Approach Time (EAT) if known, or at the ETA from the flight plan
- 5Light signals (if at an aerodrome)
Signal By ATC to aircraft on ground By ATC to aircraft in flight Green flashes Cleared to taxi Cleared to land Continuous green Cleared for take-off Cleared to land Continuous red Stop Give way, continue circling Red flashes Taxi clear of landing area Aerodrome unsafe, do not land White flashes Return to starting point Land at this aerodrome Flashing red/green General warning General warning
Fuel Emergency
Minimum Fuel
Not an emergency declaration, but an advisory that the aircraft cannot accept further delay without risk to landing with required reserves. Transmitted as: "MINIMUM FUEL, [callsign]" on current frequency. ATC will provide priority handling, but the pilot must still declare MAYDAY if the situation deteriorates.
MAYDAY FUEL
Declared when fuel state is such that landing at a suitable aerodrome with required reserves is no longer possible. Treat as full MAYDAY. Example: "MAYDAY MAYDAY MAYDAY... fuel critical, request immediate landing."
Key distinction: “Minimum fuel” is an advisory — it tells ATC you have no time to spare. “MAYDAY FUEL” is an emergency declaration — it means you will not reach a suitable aerodrome with required fuel reserves at the current rate of consumption. Declare early rather than late.
121.5 MHz — International Distress Frequency
121.5 MHz is the international aeronautical emergency frequency, monitored by all ATC units, most commercial aircraft, and military aircraft worldwide. It is also used by ELTs (Emergency Locator Transmitters) which transmit on 121.5 and 406 MHz when activated. Always try 121.5 MHz if no response on the assigned frequency.
| Frequency | Name | Use |
|---|---|---|
| 121.5 MHz | International Distress Frequency (VHF) | Primary aviation emergency frequency. Monitored by all ATC, commercial & military aircraft. |
| 243.0 MHz | Military Distress Frequency (UHF) | UHF equivalent of 121.5 MHz. Monitored by military aircraft and some ground stations. |
| 406 MHz | ELT Distress (satellite) | Modern ELTs transmit on 406 MHz for satellite detection via COSPAS-SARSAT, plus 121.5 MHz for homing. |