Eighteenth Air Force (Air Forces Transportation) (18 AF) is the only Numbered Air Force (NAF) in Air Mobility Command (AMC) and one of the largest NAFs in the United States Air Force. 18 AF was activated on 28 March 1951, inactivated on 1 January 1958, and re-activated on 1 October 2003. 18 AF is headquartered at Scott Air Force Base, Illinois.

A Numbered Air Force (NAF) is a type of organization in the United States Air Force that is subordinate to a major command (MAJCOM) and has assigned to it operational units such as wings, squadrons, and groups. A Component Numbered Air Force (C-NAF) has the additional role as an Air Force Component Command exercising command and control over air and space forces supporting a Unified Combatant Command. Unlike MAJCOMs, which have a management role, a NAF is a tactical organization with an operational focus, and does not have the same functional staff as a MAJCOM. Numbered air forces are typically commanded by a major general or a lieutenant general.