The Raytheon Sentinel is a retired airborne battlefield and ground surveillance aircraft formerly operated by the Royal Air Force (RAF). While based on the Bombardier Global Express ultra long-range business jet, the prime contractor for the Sentinel was the American defence firm Raytheon, which supplied most of the mission systems and performed the integration work.
Originally known as the ASTOR (Airborne STand-Off Radar) programme, procurement of the type started during 1999. Following its delivery in 2007, the Sentinel fleet was operated by an RAF squadron manned by both air force and army personnel. The Sentinel was interoperable with other allied systems such as JSTARS and the NATO Alliance Ground Surveillance (AGS) system. Sentinels were deployed overseas on multiple occasions, such as in support of the British Army in Afghanistan, coalition forces in Libya, and to assist French forces deployed in Mali. The type also saw smaller-scale deployments in Ghana and even domestically to assist disaster relief operations.