But rustle, if you don't declare a Mayday, how is ATC going to know that it has to launch a big green rescue helicopter with Charlton Heston aboard in a spirited but flawed air-to-air rescue attempt? You'll be bravely fighting the controls on your own without all that extra help that ATC can provide you with to keep your aircraft flying the right way up...
Tongue in cheek I know, one wonders how much help ATC can really provide, fly the aircraft, manage the problem, thats going to save you in most cases.
However, I have witnessed three pans. Everyone who hears the call is on the look out for the aircraft. The airways are silenced. Every possible assistance that ATC could provide comes your way. In a non controlled enviroment everyone is doing their best to stay out of your way at a time when your eyes may well not be outside the cockpit. Nothing is too much trouble.
If something unexpected happens on landing the fire and rescue services are prepared.
I lost a very good friend of mine in a light aircraft accident. The medics reckon both people were alive at the crash site and if they had been found more quickly may well have lived. They never declared a mayday or pan although talking to the AIB it was clear they knew they had a problem some considerable while before.
I agree with Astro - how can you ever be certain you know the full extent of the problem? How do you know there is no collateral damage? How do you know the problem is not about to cascade? If you have made the mayday, at least that is one less thing to worry about if the problem escalates.
I guess you are never going to be criticised for calling a mayday, but might you be for not? Captaincy it is, and in an emergency isnt that about taking every precaution at your disposal?