[ I got a bit carried away - if this is too long for you, skip to the bottom section, and tell me how to do the "two-handed" aiming method so that it works. Thanks! ]


I'm sure many people in distress who tried to use a signal mirror were rescued later than they might (or not at all),
because they had no idea to use a signal mirror properly - two-handed or otherwise.

I corresponded with such rescuee within the year - she tried to signal the helicopter, but had no idea how to direct the beam, so the helicopter didn't see her flash.

Also - regarding range - I'd expect the first opportunity to catch someone's attention with a signal mirror is at least a mile in most cases.

I don't know about land practice, but for maritime rescue, my understanding is that the search pattern for survivors expected to use signal mirrors
(they know you have a signal mirror because you checked the 5th box in the first column under "Safety and Survival" when you filed your Float Plan),

US Coast Guard search doctrine ( COMDTINST M16130.2F Table H-20) is to assume a 5 nautical mile sweep width,
which I understand to mean that a search plane/helicopter will fly passes 5 nautical miles apart so there is a 50%
chance that there closest approach will be 1.25 to 2.5 nautical miles, and you'd better be sure of hitting them with a bright flash at that range.

There are three precise signal mirror aiming methods (retroreflective aimer, double-sided mirror, small hole + foresight), that are easy to use, easy to improvise, and accurate.

In WW2 there was a Coast Guard Test(right column) of novice subjects bobbing in a raft signaling to a scout plane, using various signal mirror aiming methods.
The results (in number of flashes seen per minute) were:

• Retroreflective aimer 35 (2.5 times better than the next best)
• Double-sided mirror 14 (the incumbent)
• manufactured foresight aimer 8 (British)
• Improved foresight aimer 0.3 (top of buddy's oar)

Since land is much steadier than a bobbing raft, I would expect the spread to be less on land, and, unfortunately, I have never seen a similar test on land. I have, however, used
all of these methods (save the buddy with the oar) on land, and all worked better for me than the "Vee-finger" at my best.

I do note that the Boy Scouts used double-sided mirrors quite successfully in their Operation On-Target peak-peak signal mirror event for 29 years,
and the US Coast Guard will accept a double-sided signal mirror as meeting the requirement that lifeboats in oceangoing US vessels carry a USCG approved signal mirror.

The Boy Scout leaders do tell me they find the retroreflective aimer mirrors much easier to use than the double-sided mirrors.



The thing I like about the retroreflective aimers is that in a minute or two, I can teach a Boy Scout how to use it well enough to hit me at twenty miles with a home-made retroreflective aimer mirror.

If cost is the concern, this page on making your own signal mirror teaches how to make both retroreflective aimer and double-sided aimer glass signal mirrors.

Based on your next, I think your suggestion is that the Vee-finger method is an adequate alternative, and that you have had success with that.

To my mind, the "vee-finger" method is a "foresight" aiming technique. In the table above, on water, even with a
manufactured foresight, was less than 1/4 as effective as a retroreflective aimer, but I expect you are thinking about land, and thinking that the "vee-finger" will be "good enough".

A photo of the foresight mirror tested in WW2 is this British Heliograph-style signal mirror.

This type of signal mirror is popular in CommonWealth countries, and is in many foreign lifeboat kits. Here's a YouTube demonstration:






I think by "two-handed" aiming technique, you mean the "Vee-finger" method taught by the US military and others for use with a plain mirror.

I've spent a fair amount of time trying this method, and it seems like a purely horrible idea to me, but if you've had success with it, perhaps you can explain where I've been going wrong.

First, I've always assumed that I'm trying to hit the target with the sunbeam that I can see visible on a shadowed wall 100 ft away.
That beam is the same subtended angle as the sun, and is much narrower than the "Vee" between my fingers held up, or my fingers themselves -
it is about 1/3 the width of my finger - about the width of Lincoln's head on a US penny held at arms length, or an 18 inch radius at 100 yards. Here's a photo illustrating this:



Perhaps my standards for a "hit" are too high? I know that this very intense narrow beam
(I've used 2"x3" glass mirrors to signal to, or be signaled to, 20 miles or more),
is surrounded by a weaker beam that causes a noticable "glow" that an observer sees as the angle between the main beam and the observer shrinks.
At close range, the "glowing" mirror is apparent, and maybe even at significant longer range.
If the "glow" is visible at 2.5 nautical miles, then targeting is less of an issue.

If we are trying to hit the target with the "main beam",
then my "vee fingers" seem like pretty blunt guides for
aiming that narrow beam.

Also, if we are trying to use the "main beam", most of
the instructions I've seen would (if followed) pretty
much guarantee I will miss the target with confidence
for any mirror that lacks a sighting hole.

The issue is parallax - the line from the center of the
mirror to the target cannot be parallel to the line from
my eye to the target (since I can't look through the mirror,
absent a hole). I can neatly center the rectangle of light
on my spread fingers, look past the very side of the mirror
at a plane dead center between my fingers, and miss it by
many times the width of the main beam.

I've read dozens of written instructions (including numerous US military manuals, and Doug Ritter's instructions appended to his retoreflective aimer instructions,
here: Doug Ritter's Rescue Flash Instructions (and Vee-Finger) and viewed numerous videos on this technique,
including the section on "Vee-finger" in the Peter Kummerfeldt Signal Mirror Video

My conclusion is that anyone using most of the instruction material online for "Vee-finger" aiming will never hit a
target at a mile or two (because they will be carefully
aiming away from the target.)

However, people seem to love this technique - what am I missing?