astor has its roots in the british army's corps airborne stand-off radar (castor) programme which in 1984 modified a britten-norman islander (g-dlra/zg989) with a large nose radome for battlefield surveillance. the 1991 gulf war confirmed the requirement for such an aircraft, but the end of the cold war made funding difficult. the production contract was signed in december 1999 with a projected in-service date of 2005.