Aerospace co-ordinates

Ok, So I'm writing a book, and In it my characters have to tell each other where they are above the city. I know it takes into account angle, altitude, and lat/longitude, etc.

Thing is, I don't know the standard formula or format to put this in! I know it has in it, Just how to SET IT UP.

Technically they're communicating pilot-to-pilot, If that helps

Any aerospace nerd willing to help me with this? Any links ore explanation would be wonderful ♥

GPS-- Latitude (N or S degrees minutes), Longitude (degrees, minutes) and altitude (meters or feet above mean sea level MSL or Angels XX where XX is in thousands, like Angels 25 is 25,000).
Radio-- as in VOR (VHF omnidirectional range) or NDB (non-directional beacon).
http://en.wikipedia.org/wiki/VHF_omnidir…
http://en.wikipedia.org/wiki/Non-directi…
These radio positions are usually described as degrees of heading from true north.
DME (Distance Measuring Equipment) gives nautical miles of distance in slant range.
http://en.wikipedia.org/wiki/Distance_me…
TACAN is military version of above, can be used by civilians.
http://en.wikipedia.org/wiki/Tactical_Ai…

http://en.wikipedia.org/wiki/Celestial_c…

http://www.google.com/search?q=celestial…