RRH Buchan is an air defence radar station operated by the Royal Air Force, located at Stirling Hill, 3.2 kilometers south of Peterhead on the Aberdeenshire coast of northeast Scotland. It was originally opened in 1952 as RAF Buchan, an Air Defence Radar Unit. As part of the UK Air Surveillance and Control System, it functioned as one of two Control and Reporting Centres (CRC) for monitoring air traffic in and around UK airspace, and was the parent station for remote radar heads at Saxa Vord and Benbecula. In 1979, operations moved to interim facilities while the underground operations block was refitted. Following the collapse of the Warsaw Pact in 1991, Buchan continued as a CRC, responsible for UK airspace north of Newcastle, processing information from reporting posts and civilian radars to create the Recognized Air Picture (RAP). It also provided tactical control of air-defence aircraft. In May 2000, the Ministry of Defence announced its downgrading from a manned RAF station to a remote radar head. The radar unit ceased to be an RAF station on 1 September 2004, becoming Remote Radar Head Buchan. The domestic accommodation site was sold in 2012. In 2015, its Lockheed Martin AN/FPS-117 radar was replaced with a new Lockheed Martin AN/TPS-77 system, funded by wind farm developers to mitigate interference. In 2017, the unit's radome was replaced. As of 2020, a program called HYDRA began to upgrade Remote Radar Head sites, including Buchan, with new communications buildings, radar towers, and perimeter security. RRH Buchan currently operates a Lockheed Martin AN/TPS-77 long-range surveillance radar, collecting data for the UK Air Surveillance And Control System (ASACS) based at RAF Boulmer. Radar Flight (North) of the ASACS Engineering & Logistics Squadron oversees its operational availability. As of January 2024, twenty UK Armed Forces Service personnel are based at Buchan.