If a MAYDAY is declared by an airliner, will ATC automatically alert the external services to attend the airfield, or is it dependant upon the nature of the emergency.
If the emergency is then downgraded graded to a PAN, can the external services be cancelled and return to their bases before arriving at the airfield. If the external services cannot be cancelled en route, is there any point downgrading the MAYDAY to PAN status.