The Boeing WC-135W Constant Phoenix was the legacy U.S. Air Force atmospheric-collection variant of the KC-135 family. Modified from C-135 platforms, it collected particulate and gaseous effluents for nuclear-detection and treaty-monitoring missions before the Air Force transitioned its two-aircraft WC-135W fleet to three WC-135R aircraft in 2023.
Alerts for directly linked future launches and major activity.