Declaring an emergency: MAYDAY, PAN-PAN, and working ATC

The right word doesn’t just describe your trouble — it decides how much of the sky and how many people are yours to command.

The idea

Radio words are a ladder. A plain priority request asks for help without declaring anything. PAN-PAN is the urgency call — a real problem, not yet grave. MAYDAY is distress — grave and imminent danger. Each rung obliges controllers to do more, and unlocks more authority for you.

Under it all sits one hard rule that outranks even ATC: if your collision-avoidance system commands a manoeuvre, you fly the manoeuvre — because it is the only instruction built from the real-time geometry of both aircraft.

build the call — slide the severity, add what ATC and SAR need

Severity

priorityPAN-PANMAYDAY

the transmission

message: 0 of 4 key elements.

what this level unlocks from ATC

Start at a priority request, then slide up. Watch the obligations and authority you unlock at each rung.

the rule that outranks ATC — a TCAS resolution advisory

You’re level at flight level 350. Two instructions arrive in the same second. Which do you fly?

How it works

Pick the rung that matches the actual danger, then say the standard things so controllers and search-and-rescue can act without asking twice. Each signal is spoken three times.

escalation ladder          means                                   you get
priority request           help wanted, no emergency               handling "as able"
PAN-PAN (x3)  URGENCY       safety affected, not yet grave          priority + coordination
MAYDAY  (x3)  DISTRESS      grave & imminent danger                 absolute priority + authority

what to transmit (a workable order):
  [signal x3] - [who you're calling], [your callsign],
  nature of the emergency,
  present position and level,
  intentions (what you're going to do),
  souls on board,        # people, for rescue planning
  fuel remaining.        # endurance in TIME, not pounds

the override rule:
  TCAS resolution advisory  >  conflicting ATC instruction
  fly the RA -> announce "TCAS RA" -> when "clear of conflict",
  return to the clearance and report.

When to use it

Say…	When…
Priority request	You want quicker handling but there’s no real hazard — a minor snag, a passenger who needs to be met.
PAN-PAN	A genuine problem affects safety but you are not (yet) in grave danger — a single system failure you’re managing, a medical case that is stable.
MAYDAY	Grave and imminent danger — fire, engine failure with limited options, loss of control, imminent ditching. When unsure between PAN-PAN and MAYDAY, err up.
The trade-off	Under-declaring costs you priority and authority you may urgently need; you can always upgrade PAN-PAN to MAYDAY, so it’s never worth downplaying real danger.

Watch out for

Under-declaring to . A “we’d like priority” when the cabin is filling with smoke buys none of the protection a MAYDAY commands. The word is not an admission of failure — it is a tool.
Forgetting souls and fuel. Controllers ask for these for rescue and diversion planning. Fuel is stated as time remaining (endurance), not a weight or quantity.
Flying the radio before the aircraft. , navigate, then communicate. A perfect MAYDAY transmitted while the aircraft is mishandled helps no one.
Obeying ATC over a TCAS RA. The 2002 Überlingen mid-air collision turned on a crew following a controller’s descent against their climb RA. The RA is coordinated between both aircraft; the controller cannot see that. Always fly the RA.
Not closing the loop after the RA. Follow the RA, tell ATC “TCAS RA”, and once “clear of conflict” return to the assigned clearance and tell them — don’t leave the controller guessing.

Worked example

An interviewer asks: “Number-two engine fails and you see smoke. Walk me through the call.” A strong answer flies first, then declares at the right rung: “MAYDAY, MAYDAY, MAYDAY, Denver Center, Speedbird 42, number-two engine failed with smoke in the cabin, overhead Pueblo flight level 350, diverting Colorado Springs, request descent and vectors, 148 souls on board, 2 hours 10 minutes fuel.” That single call gives ATC the nature, your intentions, and the two numbers rescue needs — and it claims absolute priority plus the authority to deviate as the emergency requires. If, mid-diversion, TCAS commands “DESCEND” while ATC has just said “climb,” you follow the RA, call “TCAS RA,” and rejoin the clearance once clear.

Check yourself

A cargo-hold smoke warning has just illuminated and you elect to divert immediately. Which call fits?

TCAS orders “CLIMB” the instant ATC clears you to descend for traffic. What do you do?