Boeing C - 135 Stratolifter The Boeing C - 135 Stratolifter is a transport aircraft derived from the prototype Boeing 367 - 80 jet airliner ( also the basis for the 707 ) in the early 1950s . It has a narrower fuselage and is shorter than the 707 . Boeing gave the aircraft the internal designation of Model 717 . Since the first one was built in August 1956 , the C - 135 has been a visible fixture of the United States Air Force . Development . 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 . As is the case with the KC - 135 , the C - 135 is also recognized as the Model 717 by Boeing . C - 135A / E / R . Fifteen C - 135As , powered by Pratt & Whitney J57 turbojets , were built . In later years , almost all were upgraded with Pratt & Whitney TF33 turbofan engines and wide - span tail planes , and were re - designated C - 135E . Later on most of the C - 135Es were re - engined again , using the more powerful turbofan engine , the CFM International F108 ( CFM56 ) . C - 135B . 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 . A number of these were modified for a weather reconnaissance ( flying through radioactive clouds from nuclear tests or other agents ) role and designated WC - 135B Constant Phoenix . C - 135C . 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 / Distinguished Visitor ( DV ) transport role seats 14 passengers , also gives a Joint Forces Air Component Commander ( JFACC ) a limited ability to plan and control the simulated battle while in the air en route to the crisis area . Speckled Trout . Speckled Trout is the official name of a combined SAF / CSAF support mission and concurrent test mission . It was also the official nickname given to a modified C - 135C , serial number 61 - 2669 , that was used by the Secretary and the Chief of Staff of the Air Force for executive transport requirements . Fully equipped with an array of communications equipment , data links and cryptographic sets , the aircraft served a secondary role as a testbed for proposed command and control systems and was also used to evaluate future transport aircraft design . The 412th Flight Test Squadron ( 412 FLTS ) of the Air Force Material Command ( AFMC ) at Edwards AFB , California operated the C - 135 Speckled Trout airframe and managed its test mission . The name " Speckled Trout " applies to both the organization and the aircraft . The name was chosen in honor of an early program monitor , Faye Trout , who assisted in numerous phases of the project . The word " speckled " was added because Trout apparently had " a lot of freckles . " Speckled Trout acquired the C - 135C , serial number 61 - 2669 , in 1974 and retired the aircraft on 13 Jan 2006 . An interim aircraft was in use for the Speckled Trout mission until the 2008 delivery of the current aircraft , a modified KC - 135R Stratotanker serial number 63 - 7980 with a more modern communications architecture testbed . The current KC - 135R Speckled Trout also supports additional tests and air refueling requirements that the C - 135C could not . C - 135F . The C - 135F were new - build aircraft used by France as dual - role tanker / cargo and troop carrier aircraft .