Everybody knows a signal mirror can save your bacon if you’re lost in the wilderness, but how many of us actually know how to use one? At risk of posting something of actual use to actual hikers, here’s a link with an illustration showing exactly how to use a signal mirror (you have to scroll down a ways for all the details– it’s on a page for small-aircraft pilots).
The item also weighs whether people should bother with old CDs like the ones AOL used to mail out in quantity. The conclusion: No.
In tests a CD proved to be only about 20%-25% as effective (distance and brightness at distance, judged subjectively) as a 3 x 5 mil-spec plastic signal mirror, a bit more effective, but not even 50% compared to a small 2 x 3 mil-spec plastic signal mirror. It would compare worse against higher quality mirrors.
From an operational persepctive, in an After-Action Report of a major SAREX (Search and Rescue Training Exercise) conducted in 2001 by the Colorado Wing of the Civil Air Patrol, the conclusions were, “that “victims” who had never used a signal mirror (with the aiming hole in the middle) were able to use them effectively, while CD’s (AOL etc.) are useless as signal mirrors.”
A good signal mirror can send a flash for miles, but it has to be aimed at at somebody who’ll see the flash.
This is another useful page on Doug Ritter’s excellent “Equipped to Survive” site. It’s kind of an in-depth resource that expects you to develop some significant skills in order to use his advice.
One thing this article doesn’t seem to say clearly, is that if all you can do with a signal mirror is make random flashes, you’re not going to be able to communicate much useful information to anybody. You might be mistaken for something more random like a vehicle in a distant road, a passing aircraft, or even some random trash a mylar balloon blowing in the wind. If you really want a signal mirror to be useful you need to learn Morse Code.
You wouldn’t need to know *all* Morse code — but knowing a word or two (or the standard SOS code) would be helpful.
No, you wouldn’t have to learn the whole code. But consider that for most people, nothing is more frustrating to the person on either end of a conversation than to think someone understands you, and then to find out that they don’t.
Imagine that you’re in trouble somewhere. If you only know a few set phrases in Morse code, you can say that you need help, but you can’t understand the questions that follow from your would-be rescuer about the kind of help that you need. They indeed don’t know how dire your situation might be, or even whether you’re just some kids playing a prank.
I think that if you’re going to carry a signal mirror, it’s far better if you learn how to actually communicate with it.