Royal Air Force Fylingdales or more simply RAF Fylingdales is a Royal Air Force station on Snod Hill in the North York Moors, England. Its motto is Vigilamus. It is a radar base and is also part of the Ballistic Missile Early Warning System (BMEWS). As part of intelligence-sharing arrangements between the United States and United Kingdom, data collected at RAF Fylingdales are shared between the two countries. Its primary purpose is to give the British and US governments warning of an impending ballistic missile attack. A secondary role is the detection and tracking of orbiting objects; Fylingdales is part of the United States Space Surveillance Network. As well as its early-warning and space-tracking roles, Fylingdales has a third function – the Satellite Warning Service for the UK. It keeps track of spy satellites used by other countries, so that secret activities in the UK can be carried out when they are not overhead. The armed services, defence manufacturers and research organisations, including universities, take advantage of this facility.

The RCA 474L Ballistic Missile Early Warning System was a United States Air Force Cold War early warning radar, computer, and communications system, for ballistic missile detection. The network of twelve radars, which was constructed beginning in 1958 and became operational in 1961, was built to detect a mass ballistic missile attack launched on northern approaches [for] 15 to 25 minutes' warning time also provided Project Space Track satellite data.