February 9, 1972: Airworthiness Evaluations of EC-137D Begin

An Air Force Flight Test Center test team began series of airworthiness evaluations of an EC-137D at the Boeing facility in Seattle, Washington. The EC-137D was a Boeing 707-382B with a 30-foot rotating radome mounted above the fuselage. The aircraft would be an integral part of the Airborne Warning and Control System under development.

USAF 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 pounds  dry thrust Pratt & Whitney J57 (JT3C6) turbojets; when subsequently re-engined with 18,000 pounds 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 several C-135 airframes to VC-135 VIP standard, and these were used for staff transport mainly within the United States.