The National Nuclear Security Administration's (NNSA) Office of Secure Transportation (OST) maintains a fleet of seven aircraft to transport sensitive items, equipment and security personnel. Based on increasing requirements for transporting components and security personnel, OST decided to add a heavy transport aircraft to meet the Department's weapons surety and emergency response missions. In 2004, as a replacement following the sale of a portion of its fleet, OST acquired a DC-9 cargo aircraft that had been excessed by the U.S. military. Prior to integrating the DC-9 into its fleet, NNSA ordered a refurbishment of the aircraft. This refurbishment project was to permit the aircraft to be certified to civil air standards so that it could transport passengers for site visits, training and other travel. The NNSA Service Center (Service Center) awarded a contract for the refurbishment of the aircraft in December 2004.