Readiness Program In support of the U.S.
Test Readiness Program that was initiated in response to the
Limited Test Ban Treaty (LTBT) of 1963,
Sandia National Laboratories configured three NC-135 aircraft as flying laboratories to support atmospheric testing of nuclear weapons, should testing resume. These aircraft were based at
Kirtland Air Force Base. Work was initiated in 1963 and the aircraft remained in service until 1976, flying principally for Sandia, the
Los Alamos National Laboratory, and the
Lawrence Livermore National Laboratory. The
Atomic Energy Commission (AEC) maintained controlling oversight of the NC-135 flight test aircraft. After 1976, the aircraft flew for
Air Force Weapons Laboratory.
Airborne astronomy missions While flying simulations for the Test Readiness Program, the science teams assigned to the NC-135 aircraft realized that their flying laboratories could be effectively used to study
solar eclipses as well as
cosmic rays entering the atmosphere and the effects of magnetic fields in the
ionosphere. Program scientists petitioned the AEC to allow for a program-within-a-program to use the aircraft for such scientific research. The petition was approved, and research continued through 1975. The first eclipse mission took place from
Pago Pago International Airport in 1965. Flying in conjunction with several other science aircraft, one of the NC-135s managed to fly within eclipse totality for 160 seconds, providing valuable science data. Eclipse missions were also flown in 1970, 1972, 1973, 1979 and 1980. On March 15, 2007, the YAL-1 successfully fired this laser in flight, hitting its target. The target was the NKC-135E
Big Crow 1 test aircraft that had been specially modified with a "signboard" target on its fuselage. The test validated the system's ability to track an airborne target and measure and compensate for atmospheric distortion.
Big Crow aircraft were also used as downrange telemetry assets in conjunction with
Western Launch and Test Range launches from
Vandenberg Air Force Base in California. Since 2008, 55-3132 and 63-8050 have been retired, and relegated to the
AMARG (Davis-Monthan AFB, Tucson, AZ).
Other versions One aircraft, serial 61–2666, has been modified as an NC-135W to test systems and equipment used on RC-135V and W Rivet Joint reconnaissance aircraft. As of September 2023, 61-2666 has been withdrawn from use and stored at DMA. From 1975 to 1984, the US used an NKC-135 for its
Airborne Laser Lab program. The modified NKC-135A carried a 10.6 micrometer Carbon Dioxide Laser. Tests included successful interceptions of small
air-to-air missiles (such as the
AIM-9 Sidewinder) and of
drone aircraft. Despite the combat potential of the system, it was kept strictly experimental. However, the
SCUD threat faced during the
Gulf War reignited interest in an airborne laser system, resulting in the
Boeing YAL-1. ==Operators==