The 99th Air Refueling Squadron is part of the 6th Air Mobility Wing at MacDill Air Force Base, Florida, but is stationed at Birmingham Air National Guard Base, Alabama. It is an Active Associate Unit, an active duty component attached to the Alabama Air National Guard's 117th Air Refueling Wing. The 99th Air Refueling Squadron works with, supports and flies the 117th Air Refueling Wing's Boeing KC-135R Stratotanker aircraft.