Field reference

Ground-to-air signals

The symbols to lay out on open ground so a search aircraft can read them: the five in today's international code, how big to make them, how a pilot replies, and what the older survival-card symbols mean.

The international code

These five symbols are the survivors' code in ICAO Annex 12, the international standard that search and rescue crews work to. If you learn only one set, learn this one.

VRequire assistance: Rocks, logs, torn clothing, trampled vegetation, any contrast material.
XRequire medical assistance: Rocks, logs, brightly colored fabric, snow trench.
NNo or negative: Rocks, logs, clothing, any high-contrast material.
YYes or affirmative: Rocks, logs, clothing, any high-contrast material.
ArrowProceeding in this direction: Rocks, branches, clothing; point arrow toward direction of travel.

Make them big enough to see

2.5 m(8 ft) long, at least. Bigger is easier to spot.

ICAO asks for each symbol to be at least 2.5 metres (8 feet) long and as conspicuous as possible. Lay it in a clearing with as much open sky above it as you can find, in a material that stands out against the ground: dark on snow or sand, light on soil or grass.

If you have nothing better, ICAO suggests:

strips of fabric
parachute material
pieces of wood
stones
tramping or staining the ground (with oil, for example)

How a pilot replies

Once an aircraft has seen your signal, the pilot tells you whether it was understood:

By day: Rocks its wingsUnderstood
At night: Flashes its landing lights on and off twice (navigation lights if it has no landing lights)Understood
Day or night: No signalNot understood

The older code

Many survival cards and older manuals print a longer emergency code, as on the US Forest Service's "Visual Emergency Signals" card. It isn't part of today's international code, so a pilot may not know it. Use the five symbols above wherever they cover what you need.

X has changed meaning. In the older code it meant "unable to proceed". Today it means you need medical help.

F: Require food and water
K: Indicate direction to proceed
Triangle: Probably safe to land here
L L: All well
J L: Not understood

Offline in ColdBoot

Ground-to-Air Signals, with no signal.

ColdBoot's Ground-to-Air Signals tool keeps both codes on your phone, the international one first and the older one labelled, with how big to make each symbol and how a pilot replies. It sits in the Comms module with Morse Code and the Digital Whistle, and it opens from the Emergency guide's entry on ground-to-air symbols and from the app's search.