Emergency communications under IFR are the highest priority traffic in aviation. When your aircraft faces immediate danger or a serious situation requiring assistance, you declare an emergency using MAYDAY (distress) or PAN-PAN (urgency). These words have no meaning in everyday English; they are pure aviation procedure words with legal, international significance.
MAYDAY is declared when your aircraft faces immediate and life-threatening danger. Examples include:
  • Engine failure or fire
  • Structural damage
  • Uncontrollable descent
  • Severe medical emergency on board
  • Fuel exhaustion imminent with no diversion option
  • Pressurization loss at high altitude
  • Uncontrollable flight control failure
PAN-PAN is declared when your situation is serious and requires assistance, but is not yet life-threatening. Examples include:
  • Single-engine failure with an engine still operating (twin-engine aircraft)
  • Electrical system failure or significant loss of instruments
  • Hydraulic system failure with backup available
  • Minor structural damage with aircraft still controllable
  • Fuel situation degraded but land-able alternatives exist
  • Medical emergency that is serious but stable
  • Engine problem with uncertain severity
The distinction matters: MAYDAY triggers emergency response from rescue and fire services. PAN-PAN alerts ATC to prioritize your handling but does not automatically activate rescue. Choose correctly, or ATC may question your declaration.