The Pioneers learned and practiced how to assemble atomic bombs and how to load them onto aircraft for long range missions. The aircraft used for these practice missions were Boeing B-29 Superfortress bombers similar to the ones that flew the first atomic missions over Japan in 1945. The Pioneers and the 509th Bombardment Group (successor to the 509th Composite Group that flew the 1945 missions) flew the practice missions from Kirtland AFB to Wendover, Utah. The 509th was stationed at Walker Air Force Base near Roswell, New Mexico.