The C-135 Stratolifter is a transport aircraft derived from Boeing’s prototype 707 jet airliner in the early 1950s. Since the first one was built in August 1956, the C-135 has been a visible fixture of the U.S. Air Force.

A large majority of the 820 units were developed as KC-135A Stratotankers for mid-air refueling, however, they have also performed numerous transport and special-duty functions. Forty-five base-model aircraft were built as C-135A or C-135B transports with the tanking equipment excluded.

Fifteen C-135As, powered by J57 turbojets, were built. In later years, almost all were upgraded with TF33 turbofan engines and wide-span tail planes, and were re-designated C-135E. Thirty C-135Bs were built with the TF33 turbofans and wide-span tail planes from the start, and a small number remain in service in their original form. The C-135C designation applies to three WC-135B weather reconnaissance aircraft, which reverted to transport status. Most of the other C-135Bs were converted to various special mission variants following their service with the Military Airlift Command .

Although most of the remaining C-135 aircraft are used for transporting senior military leaders and other high-ranking dignitaries, the C-135C communications aircraft serves as an aerial test-bed for emerging technologies. Developmental tests using this aircraft have demonstrated the capability to fly precision approaches using a local area differential GPS system. This modified C-135 has been fitted with a millimeter wave camera and a radome to test the camera’s generation of video images of the forward scene in low-visibility conditions. The aircraft, which in the VIP transport role seats 14 passengers, gives the Joint Forces Air Component commander a limited ability to plan and control the simulated battle while in the air en route to the crisis area.

Variants include:

• EC-135 Looking Glass
• KC-135 Stratotanker
• OC-135 Open Skies
• RC-135 Rivet Joint
• WC-135 Constant Phoenix