John,

My experience has been (at least in the USA) that using 121.5 (VHF Guard) in a "mayday" situation is a good first step towards getting help coming to you...but it will quickly be swamped by well-meaning, curious folks (like me) who will dog-pile onto the frequency and render it practically useless for further comm. Today's event quickly degenerated into a melee, with airliners, bizjets, ATC facilities all stepping on each other as they tried to respond to the in-distress pilot.

My 2 cents would be to be your "own first responder" and SAR director if ever in that situation. Go on 121.5 to get some attention your way ("Mayday")....then pick the strongest, best able to help responder (spelled "loiter time") and direct them onto a discreet freq (123.3; 123.45, etc) to coordinate specific needs, SAR coordinates, etc. I had to do this very thing in a USAF SAR effort many years ago I was involved in, just to avoid the well-meaning, but interfering folks on the frequency from stepping on the downed folks I was trying to get position data, victim condition, etc., info from. Guard frequency became totally unusable, and we had to go to a backup freq to pass info.

All of us in the military/airline biz since 9-11 are much more diligent about maintaining a listening watch on VHF/UHF Guard frequencies due to interception procedures initiated after those events. A cry for help on 121.5 in the USA, in a non-remote location (and due to line of sight...many remote ones) will get the Mounties headed your way, but you will need to (if able) take command of the intial comm effort and direct those most able to help you to another freq so as to best pass the info you'll want the SAR or other folks to know.

Hope that helped and answered the question.

Rob S.

ps-I too, am glad to hear the pilot of N130MG is safe! I worried about him all the way home!