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 Protocol states that one may wander aft of one's assigned seat, but not forward of it. Communications equipment and the cockpit are on the upper deck. There are also secure and non-secure voice, fax and data communications facilities. While the aircraft's luggage capacity is adequate to carry the belongings of the passengers, the logistics train of the President means that the aircraft must fly preceded by an aerial convoy of several cargo transports, which carry the helicopters, motorcade vehicles, and other equipment required by the presidential entourage. The VC-25A replaced the VC-137C (a military version of the Boeing 707) as