But i still think that by declaring a full emergency you are removing the rights of the PIC of the aircraft to decide the state of their aircraft and what service they require from ATC. There is only one person that can declare a mayday for an aircraft thats the PIC ( who can of course deligate this task), they are qualified to do it and only they can make that decision. It is in fact unlawful for any one else to issue a mayday on your behalf. From memory an ATCO can declare if they witness the crash or they can start alerting action if the aircraft is over due.
Not quite. From MATS 1:
'When a pilot has given certain items of information normally associated with an emergency message but has not prefixed the transmission with 'MAYDAY' or 'PAN', the controller is to ask the pilot if he wishes to declare an emergency.
If the pilot declines to do so, the controller may, if he thinks it appropriate, carry out the necessary actions as if the pilot had declared an emergency.'
There is also the catch-all, on the first page of the manual, that says:
'Nothing in this Manual prevents controllers from using their own discretion and initiative in any particular circumstance.'
That particular line is the one that haunts controllers in our nightmares.
The level of emergency response on the airfield is the domain of the tower controller, not the pilot. We are not there just to annoy you, we also have a duty to ensure the airport is used safely, and a duty of care to the other aircraft, as well as a duty of care to do what we believe is best for you. Yes, I hate the phrase 'Duty of Care' too.
Personally, if you tell me your vacuum pump has failed or whatever, and you don't want to declare an emergency but want to return to the airfield as a precaution, I'll call a Local Standby. The fire crews will get in their vehicles, but no blue lights, and no ambulances. If you have a rough running engine and a note of urgency in your voice, in a SEP, it'll probably be a full emergency. In a twin, local standby again. I don't think any of that is unreasonable, is it? However:
Vacum pump failures, alternators, giro failures, electrical faults, DV windows blowing off, doors poping open.
I agree, full emergency is an over-reaction in these cases, unless the controller has reason to suspect the situation is worse than it appears on the surface.