The OTU program involved the use of an oversized parent unit to provide cadres to “satellite groups"[4] The OTU program was patterned after the unit training system of the Royal Air Force. It then assumed responsibility for training these new groups and oversaw their expansion with graduates of Army Air Forces Training Command schools to become effective combat units.[5][6] Phase I training concentrated on individual training in crewmember specialties. Phase II training emphasized the coordination for the crew to act as a team. The final phase concentrated on operation as a unit.[7]
In December, the group moved to Charleston Army Air Base, South Carolina, where it became a Replacement Training Unit (RTU).[3] Like OTUs, RTUs were oversize units, however their mission was to train individual pilots and aircrews.[4] By the beginning of 1944, most (90%) of the AAF's combat units had been activated and almost three quarters of them had deployed overseas. With the exception of special programs, like forming Boeing B-29 Superfortress units, training “fillers” for existing units became more important than unit training.[8] With this mission change, the 400th Group and its components were reassigned from Second Air Force to First Air Force.[2][3]
However, the Army Air Forces was finding that standard military units like the 400th, which were assigned personnel and equipment based on relatively inflexible tables of organization were not proving well adapted to the training mission. Accordingly, it adopted a more functional system in which each base was organized into a separate numbered unit, which was manned and equipped based on the station's requirements.[9] Groups like the 400th Group serving as RTUs disbanded, and along with operational and supporting units at Charleston, was used to form the 113th AAF Base Unit (Bombardment (Heavy)).[3][10]
The group was reconstituted in July 1985 as the 400th Tactical Missile Wing, but has not been active since.[11]
Lineage
Constituted as the 400th Bombardment Group (Heavy) on 15 February 1943
^See Mueller, p. 89 (showing simultaneous disbanding and organization of units).
^ abDepartment of the Air Force/MPM Letter 662q, 19 Sep 85, Subject: Reconstitution, Redesignation, and Consolidation of Selected Air Force Tactical Squadrons
Goss, William A. (1955). "The Organization and its Responsibilities, Chapter 2 The AAF". In Craven, Wesley F.; Cate, James L. (eds.). The Army Air Forces in World War II(PDF). Vol. VI, Men & Planes. Chicago, IL: University of Chicago Press. LCCN48003657. OCLC704158. Retrieved 17 December 2016.
Greer, Thomas H. (1955). "Recruitment and Training, Chapter 18 Combat Crew and Unit Training". In Craven, Wesley F.; Cate, James L. (eds.). The Army Air Forces in World War II(PDF). Vol. VI, Men & Planes. Chicago, IL: University of Chicago Press. LCCN48003657. OCLC704158. Retrieved 17 December 2016.