121.5

[karrank]

just for information, if you transmit anything on 243 in UK they can DF you to within a couple of miles. Very handy for an emergency but also explains the reluctance to blabber away on guard.

Have read on the ATC forum the Brits have ground based monitors of 121.5 (can accept they have 243 also but hadn't heard that previously). Don't know if it is actually monitored or how (if it is) but they do have a screen based DF system that plots & triangulates, and returns continuous indications of people chatting away on GUARD everywhere within range...

[Capt Claret]

Given that GUARD is said on this thread not to be 121.5, I'm confused why when Capt/FO/SO Bloggs launches into a position report on 121.5, and I respond to them with en-guarde old chap, I usually get a Thanks.