The lady who owns the horse across from mine does search and rescue with the LA County Sheriff's Department. They have been doing it for years, it takes many hours of dedication- a few weeks ago she had to be in LA on a Friday evening, think Los Angeles traffic They have training on the weekends, and she is occasionally called out to help with a search for a missing hiker, missing person, ect. Your horse has to be bombproof, a good hauler, and able to settle in at a strange campground. She works a full time job and does the search and rescue on the side.
Another friend of mine did it with Orange County Sheriff's, but it's been awhile. If I had the time I would consider it, I have a friend who does it through CARDA with their dog.
Proudly Owned By Sierra, 2003 APHA Mare
In Loving Memory of Tally, April 15, 1983 - June 2, 2010
I've done it through my affiliation with Back Country Horsemen, we don't have formal training regimens but have established good working relationships with nat'l forests, etc and county law enforcement, so they do call on us for reliable help, particularly in wilderness areas. Riders and horses are expected to be proficient and self sufficient enough to be part of the solution and not contribute to further problems. And we have pretty rugged country to negotiate, too. Need to be able to use a GPS as well, so that command and control can download GPS data to keep track of what has been searched.
We (and indeed public at large) also get requests for search and recovery when a person is not found during the official search- the families hope that the remains can be found even if it's a year or two or three later.
I've trained SAR dogs. My area doesn't have official mounted SAR but the riding deputies know me and know they can call. If you're interested, first find out who handles SAR in our area (it may be organized a significant distance from you, that's okay. You could still be a first responder in yoru area.) The personal skills and equipment checklist would include first aid (then ETT, EMT, however far you'll take it--I certified as a paramedic, ACLS-instructor etc), IC familiarity, and inclement weather bivouacking as well as minimal high angle rescue (rope work, using pulley system to lift/lower a pt on a board. Ponies are great at covering ground faster than people without raising noise that would drown out a person calling for help, like a dirtbike/four wheeler would. Check out NASAR after you find out who's responsible for SAR in your area (start w/ asking local law enforcement/fire dept.) Good for you for your interest!