The History of KC-135A
Reduced Gravity Research Program

The Boeing Military Airplane Company's model 367-80 was the basic design for the commercial 707 passenger plane as well as the KC-135A Stratotanker. In 1954 the Air Force purchased the first 29 of its future fleet of 732. The first aircraft flew in August 1956 and the initial-production Stratotanker was delivered to Castle Air Force Base, Calif., in June 1957. The last KC-135A was delivered to the Air Force in 1965.

NASA 931 (KC-135A) (63-7998) the last “A” model will be retired from service on 31 October 2004. 63-7998 began its service on 22 November 1963 with the United States Air Force after being manufactured at the Boeing, Seattle, WA facility.

As of 10 December 2004 NASA 931 has completed the following:

Parabolas 34,757 year to date
Flight hours 13,605.0 year to date

For FY-04 NASA 931 completed 5,059 parabolas (This is the most parabolas flown in any year since the beginning of the program in 1959)

During its Reduced Gravity career NASA 931 averaged 3,800 parabolas and 300 flight hours per year. This aircraft was used to pathfind the weather when the shuttle was moved from Kennedy Spaceflight Center to its maintenance facility at Palmdale, CA and from the landing sites at Edwards AFB, CA and White Sand, NM to the Kennedy Spaceflight Center, FL. NASA 931 was also used for the Microwave Scanning Beam Landing System (MSBLS) alignments at the CONUS sites ( KSC, White Sands and Edwards) and the European sites at Zaragoza and Moron, Spain. Astronaut pilots also used the aircraft for Heavy Aircraft Training (HAT), this allowed astronaut pilots to get the feel of a heavy aircraft similar to the shuttle. 931 was also on a standby mission for the Trans-Atlantic Abort Landing (TAL). If the shuttle ever did an abort to one of the overseas landing sites during the launch, then NASA 931 would have been deployed to bring the crew home. The aircraft was also used to move high valued spaceflight hardware and equipment (EMU) to KSC in preparation for launch. One of NASA 931's proudest missions was to carry equipment and personnel in the recovery mission of the Space Shuttle Columbia (STS-107) and her crew.