The 840th Air Division (840 AD) is an inactive United States Air Force organization. Its last assignment was with Ninth Air Force, being stationed at Lockbourne Air Force Base, Ohio. It was inactivated on 24 December 1969. The unit was an intermediate command echelon for the Air Force Reserve, with its units being allocated to Tactical Air Command if activated. It provided command and control for assigned reserve troop carrier wings and provided staff and advisory services to assigned unit to ensure operational capability.