The use of Mayday and Pan also has repercussions in the chain of events taken on the ground (at least in the UK)
When informed of an airborne emergency the Aeronautical Rescue Co-ordination Centre take different actions for Distress and Urgency calls, things like informing local police, fire and ambulance units, bringing SAR helicopters to readiness, or even getting them in the air in anticipation of an incident. Informing the coast guard if there is a possibility of ditching, or mountain rescue teams for landing in the hills. They can even scramble a Nimrod to drop life rafts and other survival stores over ditched aircraft.