The Botswana Defence Force Air Arm is the air force of the Botswana Defence Force of Botswana in southern Africa. Chiefs of the Defence Staff Air Wing The former heads of the Botswana Armed Forces Air Wing were referred to while in office as either General Officers Commanding or Chiefs of the Defence Staff. Overview The Air Wing was formed in 1960 and is organisationally part of the Botswana Defence Force. All squadrons are designated with a Z, which is used as a designation for "squadron". The main base is near Molepolole and was built by mostly foreign contractors between 1992 and 1996. The base is a multi-stage project that included runways, taxiways, extensive shelter and ordnance storage facilities, a headquarters facility and a large complex of living quarters and support buildings. Sometimes referred to as the "Eagle" project, the base has received continual improvements since its inception. Other airports used are Sir Seretse Khama International Airport at Gaborone and Francistown International Airport in Francistown. The backbone of the Air Wing consists of a squadron of former Canadian CF-116s which are locally designated as BF-5s. Thirteen ex-Canadian CF-116s (ten single-seater CF-5As and three trainer CF-5Bs) were ordered in 1996 to replace the Strikemasters, with another three single-seaters and two dual-seaters delivered in 2000. The aircraft were re-designated OJ-1 through 16. For transport, the Air Wing uses Britten-Norman Defenders, CASA C-212 Aviocars, CASA CN-235s and C-130B Hercules. The latest addition to the transport fleet was an ex-AMARC C-130 Hercules to complement the two existing aircraft. A combination of Bell 412EP and 412SP helicopters are operated by Z21 and perform a variety of functions; search and rescue, medivac, anti-poaching and troop/VIP transport. In 1993, nine ex-US Army/AMARC Cessna O-2As were delivered for use against poaching. In 2011, Pilatus Aircraft Ltd announced that the Botswana Defence Force had selected the PC-7 MkII turboprop trainer aircraft to replace their Pilatus PC-7 fleet which has been in service since 1990. The contract value is approximately 40 million Swiss francs to procure a fleet of five PC-7 MkII turboprop trainer aircraft, with ground-based training system including computer-based training, spares, support equipment, as well as pilot and technician conversion training elements. The contract was signed in Gaborone on 13 April 2011. Botswana is also believed to operate Elbit Systems Silver Arrow and Elbit Hermes 450 UAVs. Accidents and incidents On 18 April 2002, an F-5 jet crashed