GPS coordinates are always a potential source of confusion. Some possible errors include:

A digit gets garbled and misunderstood. (Depending on which digit, and which coordinate system you are using, this can throw your location off a little bit....or a long way.)
or
The coordinate system gets confused, or not is understood at all. (Some dispatchers may not understand UTM for example.)
or
The recieving end must convert coordinates and makes a simple arithmetic error.
or
Using different (wrong) datums. (For example you are using NAD27 and dispatch assumes you mean WGS84.)


Some things you can do to minimize these kinds of problems:

1. Make sure you know how to use your GPS! (Do you understand datums, coordinate systems etc? Do you know how to convert using your GPS?)

2. Find out (if possible) if there is a prefered coordinate system in your area. (Pilots often prefer Degrees, Minutes and Decimal Minutes. Since in Alaska SAR frequently involves aviation, this is our locally recommended default.)

3. Speak slowly and clearly, and always give complete information, including datum.

4. Always ask dispatch to read back your coordinates. (Make sure they have it right before you end the conversation!)

5. If possible give a geographic reference besides the GPS coordinates. This gives a way to cross check your GPS location. ("We are at Latitude blah blah, Longitude yada yada, WGS84, on the ridge of Sheep Mountain approximately two miles north of the peak...")