NavList:

Hold the mirror near your face. Extend the other are and hold up a victory sign. Put the aircraft in line with the hole in the mirror (or edge of the mirror) and the V of your fingers making the victory sign. Move the mirror so that you see sun light flash on your fingers as it moves across the aircraft between. 

Can we have a diagram please Geoffrey?  An interesting point, how close can an aeroplane fly to the Sun before it becomes uncomfortable to look at?  We were always told forget the instructions. Just hold the mirror in the general direction of the aircraft and trust to the motion of the raft and your hand trembling for an observer in the aircraft to catch the odd flash.  Knowing my sort of luck, the Sun would be behind me in any case. 

DaveP

Fred Hebard wrote:

"What does the x do for you?"

Signaling mirrors usually have a small hole in them, if metal, or a hole in the silvering if glass. The idea is that you are trying to reflect the sun at the target using the mirror, but how do you know that you have the mirror at the correct angle?

The way you do this is to look at the target through the hole in the mirror and you will also see a reflection of your face on the other side of the mirror. On your face, you will see a dot of light due to the sun coming through the hole in the mirror. 

Now, while looking at the target through the hole in the mirror, adjust the mirror so the image you see of the spot of light on your face is superimposed on the hole in the mirror, and you cannot see the spot of light any more. The sun is now being reflected off the front of the mirror directly at the target.

Geoffrey Kolbe