Emergency Equipment & Communications

Transponder emergency codes

Three special codes a controller sees as soon as you set them — even before you call:

• 7700 — Emergency. Any nature of emergency. Squawking 7700 lights up the controller's scope and prioritizes your aircraft. Set this any time you're declaring an emergency or believe you may need to.
• 7600 — Lost communications. Set when your radios have failed but the rest of the aircraft is operating normally. Continues to work with secondary radar.
• 7500 — Hijack / unlawful interference. Set silently if you can; the controller's response is different from 7700.

Mnemonic: 7500 taken alive, 7600 can't communicate, 7700 going to heaven. Crude, but the order — 7500, 7600, 7700 — is reliable and the rhyme sticks.

If you change codes from a previously assigned squawk, set the emergency code as soon as you have a free hand; the controller will see the new code instantly. You don't need permission to squawk 7700.

121.5 MHz — the emergency frequency

121.5 MHz is the international VHF emergency frequency, monitored by ATC, GARD satellites, and most aircraft.

• If you're already in contact with a controller, declare on the frequency you're using. Switching to 121.5 means re-establishing communications you already have.
• If you're VFR and not talking to anyone, switch to 121.5 and call. Any controller who hears it will respond and coordinate.
• If your active frequency stops working, 121.5 is the fallback. ATC, en-route aircraft, and search-and-rescue all monitor it.

Some helicopters carry a second VHF or a backup handheld; a handheld monitoring 121.5 is one of the better preparedness items in mountain or remote-area flying.

The Mayday call

"Mayday" is the international distress call — used for grave and imminent danger. "Pan-Pan" (also internationally standardized) signals urgency without imminent danger. Both are spoken three times in succession.

Standard Mayday format — say it slow, say it twice if you can:

"Mayday Mayday Mayday,
[your callsign],
[your position — VOR radial, distance from a known fix, or lat/long],
[nature of emergency — engine failure, fire, etc.],
[souls on board],
[fuel remaining in time, not gallons],
[intentions — autorotation to field, returning to airport, etc.]"

Real call examples:

• "Mayday Mayday Mayday, helicopter Robinson 4-2-3 Tango Charlie, 5 miles south of KAPC at 1,200 feet, engine failure, two souls, 30 minutes fuel, autorotating to a field on the east side of Highway 29."
• "Pan-Pan Pan-Pan Pan-Pan, helicopter 12 Echo, 10 miles north of KSAC, generator failure, returning to KSAC, two souls, 40 minutes fuel."

If you have time, repeat the position information — controllers may not catch it the first time and a position fix is the most useful piece of information for rescue. If you're descending and won't have a working radio at the bottom, prioritize getting position out first.

ELT — Emergency Locator Transmitter

Required by 14 CFR 91.207 for most aircraft. Activates automatically on impact (G-switch), or can be turned on manually. Transmits on 121.5 MHz (older units) and/or 406 MHz (newer units, satellite-detected with GPS position).

• Know where yours is — typically tail boom or aft cabin. Check during preflight that the test indicator (if equipped) is functional.
• Know how to turn it on manually — the panel switch (if present) or the unit itself can be activated by hand if a survivable landing didn't trigger the G-switch.
• Know how to turn it off — false activations are common (rough landings, hard ramp handling). If your ELT goes off accidentally on the ground, call the nearest FSS and turn the unit off.
• Battery duration — typically 24–48 hours for a 406 MHz unit on full transmit. Plan rescue timelines accordingly.

The 406 MHz upgrade is significant: the older 121.5 MHz units are no longer satellite-monitored (since 2009). 406 MHz units include a unique digital ID, optional GPS position, and direct satellite alerting to rescue coordination centers. If your aircraft still has a 121.5-only ELT, the upgrade to 406 is one of the highest-value safety investments available.

Practice priorities — when seconds matter

If the emergency is bad enough that you have time only for one action, the priority order is:

1. Aviate — fly the aircraft. Communications come second.
2. Squawk 7700 — one knob turn, no words required.
3. Mayday call — if you can manage it without abandoning aviate.
4. ELT manual activation — if a forced landing is imminent and the G-switch may not trigger.

The classic "aviate, navigate, communicate" priority applies — but in the modern transponder era, squawking 7700 is so cheap (one button on most modern transponders) that it shouldn't be skipped even when time is short.