Boeing C-137 Stratoliner procurement of the Boeing 707 was very limited, amounting to three Model 707-153s designated VC-137A. When delivered in 1959 these had four 13,500 lb (6123 kg) dry thrust Pratt & Whitney J57 (JT3C6) turbojets; when subsequently re-engined with 18,000 lbf (80.1 kN) dry thrust TF33-P-5 (JT3D) turbofans they were redesignated VC-137B. Only one other variant served with the USAF: this was the VC-137C "Air Force One" presidential transport, the two examples of which were Model 707-320B Intercontinentals with specialized interior furnishings and advanced communications equipment. Two further non-presidential C-137C aircraft were later added. To supplement its VC-137s, the USAF converted
Boeing VC-25 of Lyndon B. Johnson. The current VC-25A aircraft are aging and have become less cost-effective to operate. The USAF Air Mobility Command investigated possible replacements, with early press coverage suggesting that the USAF would consider the Boeing 747-8 and the Airbus A380. On January 7, 2009, Air Force Materiel Command issued a new Sources Sought notice for a replacement aircraft to enter service by 2017 with an additional two aircraft to follow in 2019 and 2021. On 28 January 2009, EADS North America representing EADS and its Airbus division confirmed it would not respond to the US Air Force notice,