The term D.C. 9 refers to the Douglas DC-9, a twin-engine jet airliner manufactured by the Douglas Aircraft Company. The aircraft was first introduced in 1965 and was used for short-haul flights. The National Air Traffic Services (NATS) is an organization that provides air traffic control services in the United Kingdom. NATS is responsible for managing the airspace of the UK and providing air navigation services to ensure the safety of aircraft.