Yes.

JerryFountain and hikermor have testified to that from their personal experience, and I provide more examples below.

Ideally the signal mirror is backup for a 24 hr, all-weather radio distress signal, such as a 406 MHz PLB (PLB FAQ), which need only weigh 5.3 oz (150 gm) for the McMurdo FastFind , or 4.6 oz (130 gm) when the ACR ResQLink is available.

For the signal mirror, given your weight concerns, look at the <0.75 oz (21 gm) 2"x3" polycarbonate "Rescue Flash" signal mirror from American Medical Kits. (See Doug Ritter's description halfway down this FAQ ) It is a high optical quality signal mirror with a an accurate, "one-handed" retroreflective aimer that produces a bright fuzzy "fireball" aiming spot, as photographed at the left in my avatar graphic. The "Mini Rescue Flash", at 1.5"x2", is even smaller and lighter, but is less than half as bright, and not available separately.

Here are some reports of successful signal mirror rescue in snow/ice:

(A) 1990s?: Australian recounts use of signal mirror in Antarctic as standard operating procedure on his Antarctica field work to signal for helicopter pickup { his parties didn't even have radios - ouch!} and shares one of his personal experiences. [1]

(B) Jan 1964: Capt. Parker C. Peedin rescued in snow, while still snowing, thanks to his signal mirror, after 36 hours on the ground after his plane went down in a blizzard. He had received no response on his hand-held UHF radio, despite calling out all day. [2]

(C) March 24, 1963: Two in Yukon rescued 50 days post-crash after plane spots their mirror flash in snow, -10 F / -23 C weather. [3]

(D) Oct 10, 1943: Three on Greenland rock (Uummannarsuaq) rescued after after flashing ship for three hours with flashes from regulation metal RAF mirror. The shipboard observer initially dismissed the flashes as reflections from sunlight on ice and snow. [4],[5]

(E) Jan 5, 1910: Three on Antarctic Shackleton expedition rescued from floating ice floe by signaling Nimrod at 10-12 mile range for one hour with "heliograph" { size not stated - if this were the standard British military heliograph, it would have a 5" diameter mirror, and be as bright at 10 miles as a 2"x3" glass mirror at 5 miles.|[6]


A snowy background definitely reduces contrast, which reduces the range of detection, but a mirror signal will still be visible many miles away, as in Example E.

The closer you are, the brighter the mirror will be in contrast to the snow, and I can (just barely) spot the flash from a 2"x3" AMK Rescue Flash Lexan mirror at 22 miles 22 miles against a dark background with my naked eye[13].(Notes: (1) I recommend viewing this in "full screen" setting, (2) The video has low dynamic range, so it fails to convey the starlike brilliance of the flash.)

That's also one reason why you want a good mirror that provides a hard concentrated flash. You can test your mirror by reflecting the beam on a shadowed surface some 50 feet away. If you aren't seeing a nice round bright circle, you're not going to get as bright a beam as you could with a good mirror. My photo here, comparing the concentrated reflection from a Mini Rescue Flash with the diffuse reflection from a BCB Mayday mirror, is a graphic example:



I haven't seen any recent discussion about alpine climber use, but the US [7] , Australia [8], and New Zealand [9] all require their personnel carry signal mirrors in Antarctica, which has as much snow, ice (and mountains) as one might like. Also, the 2005 expedition to climb Gunnbjørn Fjeld, Greenland (highest mountain north of the Arctic circle) listed two signal mirrors in their equipment list [10].




False flashes are certainly an issue, as they were in Example D, and a lot of things have to come together for a signal mirror rescue. You need a mirror, you need sunlight/moonlight impinging on you, you need to hit the rescuer with the reflected light, they must be looking in your direction, they must notice the flash, they need to realize the flash is artificial, they have to conclude it is a distress signal, then they need to direct rescuers to your location.

Two things trained searchers should be looking for to distinguish mirror signals from natural reflections:

(a) Natural reflections from snow/ice will be steady - irregular flashes are more likely to be mirror signals (though they can be water or metal trash in the breeze). Sweep your flashes back and forth across the target.

(b) Natural flashes will persist for only a few minutes - as the sun geometry changes, the flash will go away (even more true for aerial searchers). A flash that "follows" a searcher is almost certainly a deliberate mirror signal. Be persistent.

Some things you can do to improve your odds vs. false flashes:

(a) Let potential rescuers know to look for mirror flashes:

One basic survival tactic is to leave a "trip plan" detailing your planned route and equipment with a reliable person, together with a time at which they should alert the authorities that you are overdue. If you are carrying a signal mirror, note in the "trip plan" that you are carrying a signal mirror and aren't afraid to use it. (The USCG calls this a "float plan")

(b) Try to make your flashes look different from natural flashes.

With aerial searchers, one advantage you have is that the beams from fixed natural objects don't "follow" the plane, and their duration will be short. For fixed observers, any natural fixed flash will only last for a few minutes, due to the movement of the sun. So: persevere - be obnoxious about it.

In WWII, naval personnel were told to look out for flashes that "followed them" as a sign of distress. Hopefully modern-day search personnel are still taught this.

(c) Get a good mirror with a retroreflective aimer.

Two reasons for this.

First, you'll put a lot more flashes on target than with two-handed methods, based on US and British military testing[12]. You don't want observers who take interest in your first flash to shrug and move on when they don't see it repeated in short order.

Second, if you do have to flash for hours to get someone to take note, fatigue is a serious issue. A mirror with retroreflective aimer can be used with one hand, close to your body, which is less stressing, and you can switch off arms.

(d) Practice. The beam from a good signal mirror is very narrow - about a third of the diameter of the retroreflective "fireball" bright fuzzy spot in a signal mirror (the fireball in a retroreflective mesh aimer is visible in my graphic avatar to the left of this post). For getting the hang of it, use a retroreflective target at about 100 yards range. I expect many traffic signs in the Netherlands are reflective. (Be very careful not to flash anyone within a mile or so who is operating a vehicle - at short range, signal mirrors are blindingly bright.)

Once you have mastered that, ideally you and a friend can practice at about five mile range, taking turns signalling each other and counting flashes seen/minute.

> I'm trying to shave off weight of mine equipment and every gram counts.

While mirrors are pretty light, if that's a concern, I'd recommend the American Medical Kits "Rescue Flash". According to my postal scale, here are the weights of some good optical quality signal mirrors with retroreflective aimers:

2.0 oz: glass 2"x3" Coghlan's signal mirror
1.4 oz: glass 2"x2" French Air Force Miroir SOS Type 644
0.8 oz: Starflash "Ultra" 2"x3" mirror ( keep it dry )
0.75 oz : Lexan 2"x3" AMK "Rescue Flash" designed by Doug Ritter [11]
0.375 oz: Lexan 1.5"x2" AMK "Mini Rescue Flash"

While the British 2"x2" BCB "Mayday mirror" is light (0.4 oz), and has a retroreflective aimer, the samples I've tried don't have good optical quality (diffuse beam).

=============================
REFERENCES
=============================
[1] Australian in Antarctica signals helicopter with mirror on hazy day.

http://www.mail-archive.com/sundial@uni-koeln.de/msg02583.html

[2] Civil Air Patrol Volunteer, April-Jun 2010, page 46.

http://www.capvolunteernow.com/media/cms/Volunteer_Apr_May_Jun_mag_MED_LOW_583C8A758FC2E.pdf
also here: http://www.salisburypa.com/buzzonefour.html

Capt. Parker C. Peedin rescued in snow in Jan 1964, thanks to his signal mirror, while still snowing, after 36 hours on the ground after his plane went down in a blizzard. He had received no response on his hand-held UHF radio, despite calling out all day.

[3] "I Found the Girl Lost in the Yukon" Rome News-Tribune - May 19, 1963

http://news.google.com/newspapers?id=ZAouAAAAIBAj&sjid-WDEDAAAAIBAj&pg=5719,2171329&dq=mirror

Pilot Chuck Hamilton spots Ralph Flores' mirror signal Sunday March 24th, 1963 near Watson Lake, 5 miles southeast of Aeroplane lake, leading to the rescue of Ralph and Helen Klaben 50 days after they crashed.

"The brilliant sun ... glared harshly on the stark snow ... the worst of Arctic winters had fallen on the area ... Somebody's flashing a mirror at us! - I see him!" ... I located the man again, still flashing his mirror ...

[4] Fragments of war: stories from survivors of World War II
Joyce Hibbert, Publisher Dundurn Press Ltd., 1985
ISBN 0919670946, 9780919670945 Length 267 pages

http://books.google.com/books?id=HWfbUSaTB7oC&pg=PA258&dq=mirror

"For three hours and more they took turns holding the mirror in benumbed, near useless fingers for short periods while sending regular flashes.
In mid-afternoon another lucky coincidence. An American army major decided to study the Greenland coast through binoculars. At first he dismissed the flashes on Umnaarsuk as reflections from sunlight on ice and snow. But when he noticed a puff of smoke followed by the burst and fall of light from aVery rocket, he was convinced that the flashes were also signals."

[5] Down in the North, An Analysis of Survival Experiences in Arctic Areas
by Richard A. Howard, ADTIC Publication No. A-103, April 1953, Maxwell AFB Alabama.

pp. 37-38 "the rescue of the three man from Umanarsak, has been
glamorized in popular accounts by stating a 10-cent
pocket mirror was used, but the official record states they
flashed with a regulation signal mirror.

[6] The heart of the Antarctic Being the Story of the British Antarctic
Expedition 1907-1909 by Sir Ernest Shackleton, C.V.O.
http://books.google.com/books?id=VjQNAAAAIAAJ

page 252: Chapter XX: Bluff Depot Journey, Jan 15 to Feb 16, 1909

page 256:

They went back to the depot on the 14th, and pitched camp in order
to wait for the Northern Party until the 25th, when they were to
make their way back to winter quarters, or signal for the ship by
means of the heliograph. On January 24-25 this party had a very
narrow escape from disaster.

p. 257 { on January 25th, 1909: From Armytage's report }

http://books.google.com/books?id=VjQNAAAAIAAJ&pg=PA257&dq=heliograph

" I sighted the Nimrod under sail, ten or twelve miles out. We laid the heliograph on to the vessel, and after flashing for about an hour got a reply."

p. 258 { on January 25th, 1909 }

http://books.google.com/books?id=VjQNAAAAIAAJ&pg=PA258&dq=heliograph

The Nimrod stood out into the sound, and from a distance of ten or twelve miles a heliograph was seen twinkling near Butter Point. The ship was able to get right alongside the fast ice, and picked up Armytage, Priestley, and Brocklehurst.

[7] Field Manual for the United States Antarctic Program
http://www.usap.gov/travelAndDeployment/documents/USAPFieldManual.pdf
single person survival bag contains signal mirror: p. A-18
double person survival bag contains signal mirror: p. A-20
Palmer Station Survival Cache contains signal mirror: A-33

[8] "Minimum equipment to be carried on any Antarctic trip"
http://nla.gov.au/nla.arc-10243-20020607-0000-classroomantarctica.aad.gov.au/materials/clothing.pdf
Requires in "remoter areas" of Antarctica: "signal mirrors"

[9] New Zealand Antarctica manual:
http://www.antarcticanz.govt.nz/images/downloads/publications/field_manual_2010-11.pdf
both single and double person survival bags contain signal mirrors: pp. 129, 130
Value of signal mirror: page 56
One page survival card: page 7 of pdf

[10] http://www.explorers.org/flag_reports/051laughton2005.pdf

"The two aims of the expedition were to make a number of first ascents of unclimbed mountains in the Watkins Mountains in Greenland in the area of 69° North and 029° West and to climb Gunnbjørn Fjeld, 3,673 m, the highest peak in the Arctic."

On their page 18 gear list (in addition to a PLB and an Iridium phone) they list: Heliograph aircraft signalling mirror, BCB military, quantity 2

[11] AMK "Rescue Flash" mirror weight per my postal scale, last evening, including clear envelope and protective film.
Flashes from the 2"x3" AMK at 22 miles (no snow/ice) here: http://www.youtube.com/watch?v=4JtfpaMiUqQ
Doug Ritter's story of the "Rescue Flash" mirror development here (search for "signal mirror")
http://www.dougritter.com/amk_psp_faq.htm
How to use the "Rescue Flash" (or other mirror with retrorefective aimer)
http://www.dougritter.com/psp_rescueflash.htm
Another set of instructions:
http://www.equipped.org/pp/pic2042.htm

[12] The US testing by the National Bureau of Standards and US Coast Guard is reported in the article in the USCG Air Sea Rescue Bulletin attached here: http://forums.equipped.org/ubbthreads.php?ubb=showflat&Number=197058#Post197058


[13] 22 mile Sun Flash from 2"x3" Plastic Signal Mirror (best in HD, full screen)
http://www.youtube.com/watch?v=4JtfpaMiUqQ