The MAYDAY format is strict and must be transmitted clearly. You will transmit MAYDAY three times at the beginning of your call to ensure it cuts through any frequency congestion and immediately alerts all stations. The ICAO/EASA standard format is:
  1. MAYDAY MAYDAY MAYDAY (three times, clearly)
  2. [Station called] (e.g., "Zurich Radar or "any station")
  3. [Your callsign (full callsign)
  4. [Nature of distress] (what is wrong: engine failure, fire, structural damage, fuel emergency, medical, etc.)
  5. [Intentions] (what you intend to do: "attempting to reach Friedrichshafen," "looking for a field," "declaring emergency descent," etc.)
  6. [Position] (your location, preferably as a latitude/longitude or bearing and distance from a known point)
  7. [Altitude or flight level] (current altitude)
  8. [POB] (persons on board: number of occupants including yourself)
  9. [Other useful information] (e.g., aircraft type, color, fuel remaining, souls on board who need medical attention)
All of this does not need to be shouted. Speak clearly, at a normal pace, as if you are giving a briefing. Panic in your voice transmits panic to ATC and may cause them to miss critical information. You can be frightened—that is human—but your transmissions must be clear and methodical.