What are USAF subdivisions directly subordinate to a HAF functional manager?

Field operating agencies (FOAs) are indeed the subdivisions directly subordinate to a Headquarters Air Force (HAF) functional manager. FOAs are specialized organizations focused on specific functions that directly support the needs of the Air Force. They are distinct from major commands, direct reporting units, and combatant commands because FOAs typically handle specific functional responsibilities and serve under the oversight of a functional manager at the HAF level.

Major commands (MAJCOMs) are larger organizational units that oversee a broad range of operational and support functions, but they do not report directly to HAF functional managers in the same way FOAs do. Direct reporting units (DRUs) also have a certain degree of independence but are generally larger and may report directly to a MAJCOM instead of a functional manager. Combatant commands focus on joint military operations across different services and may not be aligned under HAF functional structures.

Thus, understanding the specific role and reporting structure of FOAs clarifies why they are recognized as directly subordinate to HAF functional managers, as they operate within a specialized scope of the Air Force's functional responsibilities.