Field manual (FM) 3-04.120 serves as a doctrinal guide primarily intended for the Theater Airfield Operations Group (TAOG), Airfield Operations Battalion (AOB), and air traffic services (ATS) company commanders, subordinate leaders, and assigned personnel. It is applicable for use by the division, corps, Theater Aviation Command (TAC), Theater Support Command (TSC), as well as the Army aviation community including members of allied, coalition, special operations, and civil support forces requiring air traffic and airfield management support. It also assists Army branch schools and joint military services in teaching Army ATS operations. Army transformation and future force development of ATS will enable the tailoring of ATS capabilities as well as embedding an airfield management capability at theater airfields. This manual describes structure, mission, employment and sustainment of ATS units supporting major combat, stability and civil support operations. It establishes responsibilities and duties of key personnel and discusses planning considerations required for training, operations, and combat. FM 3-04.120 is authoritative and prescriptive but is not inflexible. Situations in combat are resolved by the intelligent interpretation and application of this doctrine. Standardized ATS operations at division and theater level are necessary for the success of modularity, readiness, and effective maneuver support operations. This FM applies to the Active Army, the Army National Guard/Army National Guard of the United States, the United States Army Reserve, and the Army civilian employees of the transformation force unless otherwise stated. FM 3-04.120 builds on collective knowledge and experience gained through recent operations, exercises, and the deliberate process of informed reasoning. Its principles and fundamentals address new technologies and evolving responses to diverse threats. It will also assist Army branch schools in teaching ATS operations.