Best Location Co-Ord Format for SAR/SMR??

Thinking about Dan Otter’s ordeal which he so kindly shared with us at the Avy Summit recently, one of the (many) difficulties that seemed to crop up for Dan's group after his accident was that when they communicated their GPS position to SAR, the recipient of the info wasn’t familiar with UTM coordinates so was (at least initially) unable determine their location. And of course those involved with the accident had better things to do that to try and figure out how to get their GPS to convert to some form of Lat/Long display.

We can have our machines set up for at least 3 lat/long formats that I know of plus UTM. I tend to favor UTM as it seems to be the more favored grid system for the more modern maps, but I would much rather keep my GPS set to the system that rescuers are most likely to be familiar with.

So the question in my mind is: What location/position coordinate format is most typically used by Sheriff Dept's and most mountain rescue folks?

I love me some UTM, but it hasn't 100% taken over the SAR world yet. We use it extensively for our K9 work, but what you'll get from other units/counties can be a grab bag.

In my experience with Snohomish County the Degrees, Minutes, Decimal Minutes format is very common, but UTM has a decent "following". Most cell phone towers seem to give some kind of more traditional Lat/Long coordinate.

Most important if you have contact is to make sure you specify what system you're using, obviously, and to make sure that you tell them the datum you're using as well.

The National S&R teams for FEMA and the State teams use the National Grid (Militarized UTM) for searching by grid zones.  The rub is that the aviation folks use Lat Long as their coordinate of choice and as some have discovered the two don't mix very well.  I use the Decimal Degree format with my GPS simply because if you are relaying coordinates to someone and have a week cellphone/VHF/UHF... signal it's much easier to relay just numbers than saying degrees, minutes, and seconds along with the number info.  I actually picked that tidbit up from a Coast Guard sea kayak rescue in the Prince William Sound of AK (not my rescue, but a follow up narrative from the rescue team).  The rescue was delayed quite a bit by poor VHF communication and too much info being relayed by the party being rescued.

The datum should be set for WGS84 or NAD83 (not much of a difference) and if you're using NAD27 expect the offset to be a few hundred feet compared to the first two (up to 900).  NAD27 is still in use for older USGS Quads and older maps, but not for much else these days.

I'm not sure what the locals use, but that's my 2cents

And a speedy recovery to Dan!!

Good info Dave, thanks.

Ditto.
Thanks, Dave.
I like the idea of using the decimal/degrees (lat/long) to simplify communications. Makes a lot of sense.
The WGS84 map datum is what I use be I would have likely forgotten to give it unless asked.
Thanks again, guys.
Good info.

Good question.

Both Marcus and I are active members of King County Search and Rescue. Part of our training is to learn how to easily convert between the different systems. However I couldn't answer the original question. So I posed the question to one of our Indecent Commanders.... Here is his response:

"Chris,

No clear answer.

Homeland Security wants everyone to go to US National Grid (USNG) NAD83.
This is essential the same as UTM NAD83 (or WGS 84).  But, part of the designator is not on the paper USGS Topos.  Plus paper USGS Topos are NAD27CONUS.

When the cellphone company gives a position from a cellphone it is in Lat/Lon Degrees and decimal degrees  (dd.ddddd N, ddd.ddddd W) , WGS84.

The ground searchers are changing over to UTM NAD27CONUS, much easier to plot in the field on a paper USGS Topo.  I always like to use Easting at the end of the first string of numbers, and Northing at the end of the second string.  Not part of the standard notation, but eliminates any doubt.

What ever is given must be clearly stated and include the Datum in addition to the coordinates.
You must go back to your GPS set up menu and verify the Datum being used.
Don't assume anything.  They sometimes default back to WGS84.

I see to many people stating Lat/Lon using "." as a separator and not a decimal point what the hey is 45.13.13?
Is it 45 degrees 13.13 minutes, or
45 degrees 13 minutes 13 seconds

If texting, it simpler to uses: 45.1313dN, 45d 13.13mN, or 45d 13m 13sN as appropriate.

Voice:  Give them the coordinates and datum. Demand that it is repeated back until the person on  the phone gets it correct.  The 911 operator may
be a problem, a SAR Deputy should be able to handle anything.   The 911
operator call is recorded, so it can be played back.

Also give 911 your cellphone number, and who the provider cellphone provider is.  This facilitates getting a GPS location from the cellphone provider. GPS from some cellphone, or position based on towers, receiving your signal"