The C-12J aircraft is the military version of the Raytheon Beech 1900C. Developed from the Super King Air business twin turboprop, the 19-seat Beech 1900C Airliner was first flown in September 1982 and entered service in early 1984. With its Pratt and Whitney PT6A-65B engines, it has a cruise speed of 268 knots with a certified ceiling of 25,000 feet and a range of 1,555 miles. Since its introduction in 1984, Raytheon Aircraft's Beech 1900C Airliner has been known as "the workhorse of the sky." The Beech 1900C consistently earns high marks for its large-airliner styling and passenger comfort. A later version of the Beech 99, the model 1900 is recognized as the favoured tier-3 aircraft. It is passenger friendly, highly reliable, and much appreciated by both maintenance and aircrews alike. A total of 250 1900Cs were delivered between 1984 and 1991 to regional airlines, special mission operators and corporations. Production then switched entirely to the current version, dubbed the 1900D, which has a taller cabin. Some commentators suggest that the Beech 1900C had some defects, and that to rectify these shortcomings while improving on the technical aspects, Raytheon went on to manufacture Beech 1900D, the most popular 19-seater aircraft in the world.
The 586th Flight Test Squadron is responsible for all Air Force flight test activity taking place over the White Sands Missile Range (WSMR). The squadron owns and operates fighter and cargo aircraft in support of avionics, guidance/navigation, and weapon system testing. The 586th has added a C-12J to its fleet of highly modified and unique test support AT-38B aircraft. The C-12J is the only test asset of its kind and provides unparalleled ability to conduct Global Positioning System and inertial navigation tests. In November 2000 Osan AFB’s 55th Airlift Flight completed its first-ever deployment where the C-12J unit supported a joint U.S./U.N. humanitarian aid mission to strife-torn East Timor. Operating for 125 days from Royal Australian Air Force Base, Darwin, Australia, four members of the flight and two Raytheon maintenance contractors formed the 55th Expeditionary Airlift Flight. The 55th EALF ferried passengers and supplies for US Support Group East Timor (USGET) on the nearly daily four-hour round-trip flights between Darwin and the austere Komoro airfield at Dili, East Timor.