Like HowStuffWorks on Facebook!

How to Use a Signal Mirror

Using a Signal Mirror

If you're stranded out in the woods or at sea, a signal mirror can save your life — that is, if you use it effectively. Some signal mirrors have instructions printed on one side to help users out. But if you don't have such an aid, here are some basic tips.

You can use a signal mirror in two basic ways. If you don't see anyone in the distance, simply sweep the horizon with the mirror, in hopes that you'll catch the eye of a rescue craft or team that isn't yet in your visual range [source: U.S. Air Force]. But once you do spot rescuers you should aim the reflected light at them, and then send a signal so that they can tell that you're a person out there who needs help.

The technique for using the signal mirror is pretty straightforward.

  1. Use the mirror to reflect sunlight on to a nearby surface like a raft or your hand.
  2. Slowly bring the mirror up to your eye, while making sure that the reflective surface is not obscured by your brimmed hat or fingers.
  3. Tilt the mirror up toward the sun (not directly into it, though), until you see a small bead of light.
  4. Once you've found the bead of light, move it toward your intended target (plane or searcher). Keep the bead of light in view as you do this [sources: Nester, U.S. Air Force].

If you're improvising your mirror, hold up two fingers in a V shape and angle the mirror (or credit card or compact) so that most of the light passes through the V. This will help you to find the bead of light.

It's possible to send detailed messages with a mirror by using Morse code, and some people carry cheat sheets to show them how. But you don't need to do that to be rescued. Just flash the mirror toward your target, and then cover it or turn it away from the target. Do that three times in quick succession. That's the international distress signal, which any rescuer should recognize [source: Nester].

Another important tip: It's crucial to know when to stop signaling. Once a vehicle or aircraft has spotted you and is zooming in to pick you up, avoid flashing reflected light into the rescuers' eyes, so that you don't cause them to become momentarily blinded and crash [source: Murray].