These are so cheap its seems silly not to have one available.( I've seen 12 mile rated radios for as little as $20 a pair on ebay.)

If you can get in the clear or over water -- and if the searchers are scanning the right channels -- you can extend your 'reach' 10 miles or more. I also read that your body absorbs much of the power so holding the unit at arms length and using an earpiece can increase your effective range. (Also consider that straight up to a plane is quite useful and seldom blocked.)

The key, of course, is power, so carry spare aa or aaa batteries.

Teacher