The National Air Traffic Service(NATS) is an air navigation service provider in the UK that provides en-route air traffic control services.

Air Traffic Control radar service is typically terminated once an aircraft exits controlled airspace or when the service is no longer needed, such as after landing at an airport. Pilots will be advised by controllers when radar service is being terminated.

NAVAIDS, Pilotage, Terrain, Radar, Reporting points, GPS, Eyesight, etc. based on location.

Traffic Department, or else Muncipality.

Air ambulance service is very safe. Whereas ground ambulances have to contend with traffic jams and poor drivers, air ambulances are in very little danger--if any--of getting into an accident.