SOS = Save Our Souls.
Mayday, is the signal used in radio transmissions.
Signals should be repeated in groups of three.
The International Mountain Distress Signal is six whistles, waves, etc a minute, followed by minutes silence, then repeat.
Choose a high point for light signals.
Signals at top of ridges should be seen from all directions.
For signalling with fires, you should place three fires in a triangle at eqaul distance apart.
Build earthwall around fires.
Smoke is good for signalling at daytime.
Light smoke will best stand out against forest or dark earth.
Use greens.
Dark smoke will show best against desert sand or snow.
Use oil or rubber.
Ground To Air Code :
I : Serious Injury.
II : Need medical help.
A : Affirmative.
N : Negative.
F : Need food and water.
LL : All is fine.
X : Not able to move on.
Wilderness Survival