121.5 V 406
The current generation of commercial units --as most aviators will know use 406 which is monitored on a continous basis by sat coverage--121.5 can be used by an asset tasked for search to get a directional fix in a local area--the early ELTS has a very high rate of spurious alarms with a low (relatively) automatic activation in a real emergency-thus continuos monitoring of 121.5 was abandoned--having used 121.5 for training/demo purposes in east Anglia(UK) the response was immediate!----121.5 still has its place alongside the newer technology!
Last edited by Dave Sharpe; 11th Mar 2014 at 18:39.
Reason: Bad Grammar!!