091 VFR Communications topic guide
MAYDAY and PAN PAN Calls
Distress and urgency are two different declarations with two different definitions, and the exam expects a scenario to be classified correctly before it even asks what you would say. Distress means grave and imminent danger requiring immediate assistance: an engine fire, a ditching, a genuine threat to the aircraft or its occupants right now. Urgency means a safety concern about the aircraft, another aircraft, or a person on board, one that does not yet require immediate assistance.
Both calls open with a spoken prefix repeated three times, both carry fixed message content in a fixed order, and both are transmitted, where practicable, on the frequency in use or on the international distress and emergency frequency of 121.5 MHz. Getting the classification right matters because distress carries absolute priority over every other transmission on the frequency, including urgency traffic.
Distress: MAYDAY
The distress prefix MAYDAY is spoken three times at the start of the message, reserved for grave and imminent danger where immediate assistance is required. The message that follows states, in order, the station addressed if known, the aircraft's identification, the nature of the distress, the pilot's intentions, and the aircraft's position, level, and heading. A shortened version, transmitting only what can be sent before the situation prevents more, is acceptable when time or workload will not allow the full sequence.
Once a distress call is made, the station that first acknowledges it becomes responsible for controlling all subsequent distress traffic, and every other station must keep silent unless it also has assistance to offer or the traffic is transferred or cancelled. The aircraft in distress, or the station controlling the distress traffic, may impose silence on any station whose transmissions interfere with the distress exchange. The distress condition is cancelled by the aircraft or the controlling station once assistance is no longer required, using a specific cancellation message rather than simply going quiet.
Urgency: PAN PAN
The urgency prefix PAN PAN is also spoken three times, and it covers a safety concern that does not, yet, require immediate assistance: a passenger medical issue being managed, a mechanical problem under control, or concern about another aircraft or vehicle. The message content mirrors the distress format, station addressed, identification, nature of the urgency, and intentions, with position and level added where they help the receiving station.
Urgency traffic takes priority over every transmission except distress, and the same frequency options apply: the frequency in use where practicable, with 121.5 MHz available if it offers a better chance of being heard. The key exam discriminator is always the severity described in the stem: language describing immediate danger to the aircraft or its occupants belongs under MAYDAY, while language describing a developing concern that is being actively managed belongs under PAN PAN.
Choosing the right call from a described scenario
Exam stems rarely use the words MAYDAY or PAN PAN in the description; they describe symptoms instead, and the candidate has to classify them. A stated engine fire, loss of control, or a need to ditch describes grave and imminent danger, so the correct first call is MAYDAY. A stated concern such as an unwell but stable passenger, or uncertainty about position without immediate danger, describes urgency, so the correct first call is PAN PAN. Matching the described facts to the two definitions, rather than to how dramatic the scenario sounds, is the whole skill being tested.
Worked example
Worked example: classifying the call
Not quite. The correct answer is B.
Correct answer: B
- A. This overclassifies a managed medical concern as grave and imminent danger. MAYDAY is reserved for situations requiring immediate assistance, and a precautionary diversion for a stable passenger does not meet that threshold.
- B. Correct. The scenario is a safety concern for a person on board that does not require immediate assistance, exactly the urgency definition, and PAN PAN still secures priority handling for the diversion.
- C. Without the urgency prefix the message is not identified as priority traffic, so other stations and aircraft on frequency have no signal to give way.
- D. This makes the same overclassification as option A with extra detail added. Naming the problem after MAYDAY does not correct the choice of the wrong prefix.
Step by step
- Identify what the scenario actually describes: a stable passenger, managed by cabin crew, with no immediate assistance required.
- Compare that to the two definitions: distress needs grave and imminent danger requiring immediate assistance, urgency needs a safety concern without that immediate need.
- The scenario matches urgency, not distress, so PAN PAN is the correct prefix, spoken three times.
- Check the consequence: PAN PAN still gives the diversion priority over routine traffic, so nothing is lost by choosing the correct, lower classification.
Common mistakes
Escalating every diversion to MAYDAY
Distress carries absolute priority and can cause other aircraft to hold clear of a frequency or area unnecessarily. Declaring MAYDAY for a situation that is actually urgency misclassifies the risk and can disrupt traffic that never needed to be affected.
Forgetting to repeat the prefix three times
The triple repetition is what makes the call unmistakable on a busy or noisy frequency. A single mayday or pan pan buried inside a longer sentence risks being missed or read as routine traffic.
Treating cancellation as simply going quiet
Distress traffic remains open until a specific cancellation message is transmitted by the aircraft or the controlling station. Other stations keep observing silence on the frequency until that message is heard, and assuming otherwise is a scored error.
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Last reviewed July 2026