The OC-135B Open Skies United StatesAir Force observation aircraft supports the Treaty on Open Skies. The aircraft,a modified WC-135B, flies unarmed observation flights over participatingparties of the treaty. Three OC-135B aircraft were modified by the Aeronautical SystemsCenter's 4950th Test Wing atWright-Patterson Air Force Base in Ohio.The first operationally capable OC-135B was assigned to the 24th ReconnaissanceSquadron at Offutt AFB in October 1993. It is now fitted with a basic set ofnavigational and sensor equipment, and placed in inviolate storage at theAerospace Maintenance and RegenerationCenter at Davis-Monthan Air Force Basenear Tucson, Arizona. Two fully operational OC-135Baircraft were delivered in 1996 with the full complement of treaty allowedsensors, which includes an infrared line scanner, synthetic aperture radar andvideo scanning sensors.