Signals used by survivors to indicate messages to the rescue teams looking for them from the air. These signals should be made from fabric or parachutes, pieces of wood, stones, or any other available material. There should be as much color contrast between the material used and the background against which the symbol is displayed. These symbols should be at least 10 ft (3 m) or higher and laid exactly as shown in the illustration. Pilots should acknowledge these signals by rocking wings from side to side.