International Inland Distress Signals
In European and North American countries there are commonly recognised distress signals for use by persons in distress to communicate with the outside world:
In the mountains and remote areas of Europe a signal (a noise such as a whistle blast, or a light flash) should be repeated 6 times within a minute, then a minute pause, followed by a further 6 signals within a minute. This cycle should be repeated until rescue arrives.
A rescuer responding to this call should respond with three signals within a minute, followed by a minute’s pause.
Here the rule is of ‘three’ – three flashes, three whistle blasts, three gunshots or even triangles of three bright objects. If the signal is repeatable it should be followed by a minute of no-signal, and then repeated.
Wherever you are in the world, a regular signal in an unusual place for an extended period of time should attract attention. To communicate with a helicopter or other aircraft then use arm signals – raise both together to form the letter ‘Y’ to indicate a positive, and lower one arm to form the letter ‘N’ to indicate a negative.