GAO examined the military services' air refueling needs, focusing on the: (1) cost to operate and maintain the air refueling fleet; and (2) impact of air refueling missions on the active and reserve forces.

GAO found that: (1) the long-term serviceability of the KC-135 tanker is questionable; (2) the cost per KC-135 flying hour is projected to increase from $8,662 in 1996 to $10,761 in 2001; (3) as KC-135 aircraft age, the number of aircraft available for operation declines; (4) from fiscal year 1991 to 1995, labor hours for KC-135 overhauls increased 36 percent; (5) depot maintenance levels increased due to a shortage of spare parts, maintenance delays, and reduced aircraft availability; (6) the Air Mobility Command (AMC) doubts that KC-135 aircraft can operate economically beyond 2020; (7) the Air Force could enhance the operational flexibility of C-5A aircraft by acquiring dual-use aircraft that combine airlift and refueling capabilities; (8) the Air Force is procuring a new transport aircraft to replace its C-5A aircraft and a new tanker to replace the KC-135; (9) the deployment rates for individual tanker crew positions approached the 120-day management limit during fiscal years 1994 and 1995; (10) air reserve units are operating at 95 percent of their potential availability; and (11) the Air Force is able to support its peacetime tanking requirements because many of its reserve crew members volunteer their time and spend more than 100 days annually training and flying sorties.