Zero Dark FallSignalling for help
Searchers look for anything that does not belong in nature: straight lines, bright colours, flashes, smoke and sound. Three of anything means distress.
Sound
- Whistle: three blasts, pause, repeat. A whistle carries much further than a voice and costs little energy.
- Listen for a reply between bursts; reply conventions differ by country.
Light
- Signal mirror: hold the mirror near your eye, extend your other hand at arm's length with two fingers in a V around the target (plane, boat, distant hill). Tilt the mirror until the bright spot lands on your fingers, then flick it across the target. A flash can be seen for miles on a sunny day. Practise in advance.
- Flashlight or headlamp: three flashes, or SOS in Morse code: · · · — — — · · · (three short, three long, three short).
- Phone screen and camera flash work at night too.
Fire and smoke
Three fires in a triangle, about 80 feet (25 m) apart, is an international distress signal. By day, add green leaves or wet wood for white smoke against dark ground, or rubber or oil for black smoke against snow.
Ground-to-air signals
Make symbols large, at least 10 feet (3 m) long, with straight lines, in an open space, contrasting with the ground (rocks on snow, dark branches on sand, trampled lines in grass).
| Symbol | Meaning |
|---|---|
| V | Require assistance |
| X | Require medical assistance |
| N | No / negative |
| Y | Yes / affirmative |
| ↑ (arrow) | Proceeding in this direction |
Being seen
Spread bright clothing, a tarp or an emergency blanket in the open. Stay near your vehicle or a clearing. Make a large SOS in the snow or sand.
Sources
- 33 CFR 175 Subpart C: Visual distress signals for boats (US government, public domain; covers boats only)
- ICAO Annex 12, ground-to-air visual signal code (summary)
- US Army Techniques Publication ATP 3-50.21, Survival, chapter on signalling (US government work, public domain)
