Signal Mirrors for Survival

Signalling is often very important in a survival situation.  If your goal is to be rescued, then ways of letting people know you need rescue and/or where you are, should be near the top of your list.  And when the sun is shining, reflecting it’s bright (and relatively infinite) light to rescuers or someone who can contact them is quite effective.

The best way to do this is known as a ‘signal mirror’.  And there are four types to consider.  Note that anything reflective CAN be used; there is one instance where a person was rescued using the holographic spot on a credit card as a signal mirror.  But only the signal mirror is really effective for signalling, and effectiveness is what you want to have on your side when your life is at risk, not just luck.

The most effective signal mirror is a mil-spec glass one.  These cannot be beat for effectiveness, but they are thick, heavy and fragile.  Not to mention they may be hard to find these days.  Plastic ones are lighter, often thinner and usually more durable and the better ones are not terribly ineffective.  Metal ones can be the thinnest and most durable, but generally are not particularly effective.  The last type is ‘flexible’, whose only good point is an ability to fit in where something better cannot fit.

In addition to material, variations include, size, layers and aiming technology.  As to size, the bigger the surface area, the more sunlight is reflected, and the better and further it can be seen.  If at all possible, go for at least a 2″ by 3″ one.  Better would be a 3″ by 5″ or 4″ by 5″, unless these are too big for your hand, won’t fit in your kit, or just cannot be found.  There are some smaller options if even a 2″ by 3″ is too big; I found 1″ by 2″, 1 1/2″ by 2″ and 1 1/2″ by 3″.  These may not be optimal, but they certainly are better than nothing.

Surface mirrors (where the mirroring is on the surface of the mirror) are cheap to make and can be quite thin.  However, there is nothing to protect the mirrored surface from scratches and other imperfections, and often surface mirrors tend to not have ultimate flatness.  These things can cause distortions, which block the light from being reflected, or send it off in unintended directions, leaving less light on the target.  Better mirrors usually have a protective layer over the mirroring, to protect it and help minimize distortions.  Glass mirrors are this way, as are some plastic ones.  Metal mirrors are almost all surface mirrored, and the only exception is very expensive and has a very long lead time (4 months or more) to get.  Generally metal mirrors are only appropriate if you need the thinnest mirror or most durable.  A good, layered, plastic mirror can be an acceptable compromise.

Not only do you want to reflect as much sunlight as possible, but you want to be able to direct it to where it is likely to be seen.  To this end, there are three ways to aim a signal mirror.  The most basic, usable by any mirror or reflective surface, is to make a ‘V’ with your fingers, use this V to find the target, then reflect the light onto the V so that most of it goes between the fingers toward the target.  This is not a very accurate technique due to the parallax error between the line from your eye to the target and from the mirror to the target.  Superior is to have a small hole in the center of the mirror.  This method is done just as when there is no hole, but looking through the hole at the spot and fingers has no parallax and is much more accurate.  But it does require 2 hands. which is not always guaranteed to be available in a survival situation.  The best aiming technology is a grid around the center hole, which ‘lights up’ when the hole and the reflected spot are aligned, allowing accurate aiming with only one hand,

Note that there are some ‘fake’ aiming technologies out there.  These are big holes which do NOT light up when the spot is aligned.  They may look good, but why give up reflecting surface for a big aiming hole which is less accurate than a small hole and still requires two hands to use?  There now are ones with a cross hair in a big hole which are at least as accurate as the small hole, but with not as much reflective surface, so are still not optimal.

I will be testing the following in a future article.  If you know of one which I should include in this test, please let me know.

Plastic 3″ x 4″ (www.m4040.com) – thin, light, aiming via a small hole

Mil-Spec Glass 2″ x 3″ (from 20 years ago)  – one hand aiming

Non Mil-Spec Glass 2″ x 3″ (from 20 years ago) – one hand aiming (alleged, to be tested)

Plastic 2″ x 3″ (UST Starflash) – light, durable, one hand aiming (alleged, to be tested)

Plastic 2″ x 3″ (SOL) – light, durable, one hand aiming (alleged, to be tested)

Plastic 2″ x 3″ (CountryCom) – light, durable, aiming via crosshairs in a big hole, nice pouch

Plastic 1 1/2″ x 3″ (from eBay) – light, thin, aiming via a small hole

Plastic 1 1/2″ x 2″ (Maratac) – light, durable, aiming via crosshairs in a big hole, nice pouch

Metal 1″ x 2″ (TOPs) – thin, durable, aiming via a small hole

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2 Comments

Filed under Emergency preparedness

2 responses to “Signal Mirrors for Survival

  1. A DANGEROUS ILLEGAL alternative for the high tech among us.
    On a cloudy day, pre-dawn or twilight, nothing brings the authorities to your location better than shining a simple laser pointer at an aircraft. Pilots hate them especially at night.
    Useful when shooting too, if you are spotting concealed game for someone, that red splash on greenery sticks out a treat when the shooter can’t see what you are talking about.
    As for battery life? I’ve had one in my kit for 5 years, never changed the battery, but it still works.

  2. John

    A standard laser is indeed dangerous to pilots and illegal for signalling planes. There is one alternative, the rescue laser (www.rescuelaser.com) which converts the coherent beam to a line. Not only is it much easier to ‘hit’ a viewer since you only have to line up in 1 dimension, but it is claimed to be harmless to the viewer, and it is specifically excluded from the laws on signalling use of lasers.

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