When the operation was still in its development stages, Armstrong and Colonel Roscoe C. Wilson were the leading candidates to command the group who was designated to drop the atomic bomb. Wilson was the Army Air Force project officer who provided liaison support to the Manhattan Project. Armstrong was an experienced combat veteran against German targets, but he was in his forties and had been severely injured in a fire in the summer of 1943. Wilson had no combat experience and was qualified primarily because of his engineering background and association with the project. Tibbets was considerably younger than both men and had experience in both staff and command duties in heavy bomber combat operations. He was already an experienced B-29 pilot, which made him an ideal candidate for the top-secret project. Tibbet indicated that the decision on what aircraft to use to deliver the bomb was left to him.