"Spoiler alert ... Houston, I think we have a problem." (from Rafowell)

You would think that in this day and age, there would be an unambiguous set of universal signals

Light blue might be good. Very dark shades of blue (ie. navy blue) are too dark and blend way to easily with dark vegetation, in my experience.

I vaguely recall hearing a USCG guy once, who said that in ocean searches, really light blue ("robin's egg blue") tended to stand out really well. I can't say, as I've not much experience in over water searches.

The good news is ... there is. The five "line-type" distress signals are an international standard, properly taught to the CAP ground crews.

Heck, even the geocaching coin tag I got in the mail this week teaches that "V" means you need assistance, and "X" means you need medical assistance![1]

The truly bad news - the Civil Air Patrol aren't teaching the people we are signaling for help ( the CAP mission scanners ) what "V" means, and they aren't telling them that when we display "X" we need medical help!

I did more digging, and it looks very bad. All three formats of the Civil Air Patrol Mission Scanner training omit "V" and say "X" means "unable to proceed" rather than the correct "Need Medical Assistance":

(a) The Mission Scanner Task Guide (Dec 2014)[2]
(b) The Mission Scanner "text" (June 2017, no less!) [3]
(c) The Mission Scanner training PowerPoint slides[4]

We'll see if my note to the CAP Academy bears any fruit ...
If so, kudos to Montanero for putting us onto this.

While we're at it - the above are the "line-style" distress signals. For the postural signals: the ground crew is taught all 10 postural signals taught to the Mission Scanner is, but the ground crew is taught an 11th postural signal to communicate to the Mission Scanner (make message drop), that isn't taught to the Mission Scanner, so they may not succeed with that one, either.

[1] I ordered the geocaching coin itself because it was a signal mirror geocaching coin (of course!). The tag is
tiny, and it abbreviated the descriptions of all 3 distress signals on it. It gives "V" as "NEED HELP" vs. "Need Assistance", and "X" as "NEED MEDICAL" vs. "Need Medical Assistance", but that's a big step up from the Mission Scanner training.

[2] The Mission Scanner Task Guide is at:
http://nesa.cap.gov/mas-curriculum-2
under: Mission Aircrew School Curriculum :
Mission Scanner Task Guide - Dec 14

the .pdf download link is:
http://nesa.cap.gov/s/Mission-Scanner-Task-Guides-Dec14.pdf

This topic is under Task MS O-2021 - the pertinent figure is the bottom half of Page 29.

[3] The relevant training text package is on:
http://nesa.cap.gov/mas-curriculum-2
under Mission Aircrew Reference Material & Slides
Basic School - Mission Scanner/Airborne Photographer
Volume 1 - Mission Scanner Text
the .pdf download link is:
http://nesa.cap.gov/s/MART-VOL-I-Scanner-Ref-Text-Rev-June-2017.pdf

The document title, and location of the distress signal table:

CIVIL AIR PATROL U.S. Air Force Auxiliary
Mission Aircrew Reference Text
Volume I Mission Scanner
Revision June 2017
Section 4.2.3 Emergency distress signals, page 55.

[4] The relevant training slide package is on:
http://nesa.cap.gov/mas-curriculum-2
under Mission Aircrew Reference Material & Slides
Basic School - Mission Scanner/Airborne Photographer
Mission Scanner Slide Presentations
Part One

the PowerPoint download link is:
http://nesa.cap.gov/s/CAP-SCN-Rev-June-13-Part-1.pptx
The slide with the missing "V" and mis-defined "X" is slide

Sorry Rafowell, I made a mistake. Thank you very much for the info. These differences are what I was seeing, but wanted to get to the official info and doctrine. What matters most is what the people in the air see and understand.

I have found that certain shades of blue work very well in most seasons, but certainly better than orange in the fall.

No experience, but I've seen several suggestions that "royal blue" is a superior color to make yourself stand out in the wilderness - often citing NASAR as their source.

I'm over quota for Internet research this week, but here's one such link:

Getting an Aircraft's Attention in the Wilderness

You're welcome - thanks very much for bringing it up, so we have at least a slim chance of correcting this situation.
Yes, and in the near term, I suppose we should take comfort that CAP training of Mission Scanners for postural ground-air signals is correct.

I guess that, interim, "X" might be our best choice for a linear ground-air signal.

Long term, the CAP Mission Scanning training should be fixed. The Mission Scanners need to understand what the survivors are saying, and
the five linear distress signals are what the FAA [1], USAF[2], National SAR manual, ICAO and IMO are telling the survivors to use. References [1] and [2] are from 2017, so should be up to date.

While the March 2017 US Army manual[3] for US army military ground-air coordination omits "V" and uses the old meaning of "X", the latest US Army survival manual (FM 21-76) I found told US Army survivors to use the five international standard linear distress signals[4].{ It seems that FM 21-76 was replaced by FM 3-05.70, but the (2002) version I found of that also teaches the standard 5 signals).}

The March 2007 multiservice manual ( Army, Marine Corps, Navy, Air Force) for Survival, Evasion and Recovery [ FM 3-50.3, NTTP 3-50.3, AFTTP(I) 3-2.26) uses the the five international standard linear distress signals[5].

There are many fewer Mission Scanners than potential people on the ground in distress, and the CAP academy already has the proper task training for the CAP ground element.


[1] The Aeronautical Information Manual (AIM) is the FAA's official guide to basic flight information and Air traffic control (ATC) procedures. The codes ar on page 417 of the .pdf
(page 6-2-7, FIG 6−2−1 Ground−Air Visual Code for Use by Survivors )
https://www.faa.gov/air_traffic/publications/media/aim.pdf

"The AIM contains the basic aeronautical knowledge information required to fly in the United States National Airspace System."

[2] AF Handbook 10-644 Survival Evasion Resistance Escape
(SERE) Operations, 27 March 2017, page 508, Figure 21-13 Signal Key
http://www.dtic.mil/docs/citations/AD1030991

[3] TC 3-21.60 VISUAL SIGNALS March 2017 page 3-18, Figure 3-31. Emergency codes

[4] FM 21-76 US ARMY SURVIVAL MANUAL, (date unknown) U.S. Department of the Army
https://archive.org/stream/FM2176USARMYS.../search/signals

[5] 20 March 2007 multiservice manual ( Army, Marine Corps, Navy, Air Force) for Survival, Evasion and Recovery [ FM 21-76-1, MCRP 3-02H, NWP 3-50.3, AFTTP(I) 3-2.26) page 31 of .pdf (p. III-3, Figure III-3. Signal Key

This interesting discussion unfortunately begs the question, "How often is a ground-to-air signal constructed?"

I know we responded to plane crashes, but the plane's occupants were either deceased or too badly injured to take any action. I imagine the situation in Alaska might be different than in the lower 48...

Good question Hikermor. As AKSAR said (it was really him this time), the most important thing is just to be seen. While the ground to air signals are taught by many organizations, it would be interesting to hear how often they are used and how effective they were.

The Boy Scout Wilderness Survival Merit Badge requires that the scouts describe (I have them construct) 5 ground to air signals: V, X, N, Y, and the arrow. According to the merit badge pamphlet, the V means require assistance, the X means require medical assistance, N for no, Y for yes, and the arrow for the direction of movement.

Even if the aerial rescue misinterprets the meaning of a signal, if they saw it they have located the isolated individual or group.

I found what I thought was a nice item to experiment with, the Brunton "Lost Hiker Kit" which has a card with ground to air signals on it. These are consistent with:

CIVIL AIR PATROL U.S. Air Force Auxiliary
Mission Aircrew Reference Text
Volume I Mission Scanner
Revision June 2017
Section 4.2.3 Emergency distress signals, page 55.

The X indicating "Unable to proceed".

The kit is not bad, and it contains a signal mirror, a small disk compass that you punch out and then float on water (I haven't tried it yet), a fresnel lens, and some decent instructions. It fits in a wallet as the form factor is flat and the size of a credit card. It is about $10 on Amazon.