The popular Bombardier (previously Canadair) Challenger business jet has attracted several military customers, among them the Royal Danish Air Force. It has four CL604 variants on the strength of Eskadrille 721 at Aalborg in northern Jutland, using them for VIP transport - not least by the Danish Royal Family - and over-land or maritime surveillance missions. Deployments are undertaken to Greenland, where a search and rescue role is executed alongside regular surveillance, while fisheries protection and pollution control are other important functions, the Danish Challengers being capable of carrying a variety of sensors.