Editor's Note: In our high-tech world, it's good to remember that there are useful, low-tech devices that can get you out of jam. This was first published in Marine Safety Update, Spring 2009.
Wouldn’t it be great if there was an emergency signaling device that was pocket-sized, visible for up to 30 miles, worked in sunny or cloudy weather, had an endless power supply, and cost less than $1? It exists and it’s been around for decades; it’s the signal mirror.
A little practice with a mirror will increase its effectiveness. On a bright day (although a mirror signal can also be seen on a cloudy day), find a target object in the same general section of the sky as the sun. Make a “gun sight” with two fingers at the end of an outstretched arm. Holding the mirror in your other hand, catch the reflection of the sun so it shines on your sight fingers. Now slowly move your sight hand, keeping the sun’s reflection on it, to the target you have chosen. Light-reflective tape affixed to a wall works well as a practice target since the reflection is easily seen.
You can track a moving search and rescue target easier using your hand as a site, than by sighting the target through a hole in the mirror. If your target is sighted with your fingers and the reflection is also on your fingers, your target will see the reflection as a steady light. Once you have perfected signaling a target object in the same general section of the sky as the sun, try signaling something in a different section of the sky. This might involve holding the mirror more horizontally. Or, by using two mirrors, you should be able to shine a light anywhere in the sky by reflecting the light from one mirror to another mirror and bouncing the light onto your target.
Signal mirrors can be made from many substances. A commercial signal mirror made for the purpose of being seen and rescued, will usually give the best performance. However, any shiny surface will work in a pinch; aluminum foil, a CD, a metal pan, and the back of a watch all have possibilities. Even the shiny hologram on a credit card was used facilitate rescue of two downed pilots off Florida a number of years ago.
Beware of signal mirrors with painted surfaces, however. See Equipped to Survive at http://www.equipped.com/phony_signal_mirrors.htm for a good discussion of mirrors and what to avoid in commercial rescue mirrors. Like most things in life, practice makes perfect. So use a nice day to go out and practice. It will make your rescue on a bad day that much more likely.