Modernizing the Aerial Tanker Fleet: Prospects for Capacity, Timing, and Cost

Abstract : The Air Force has for several years been pursuing programs to modernize and expand the capacity of its aging fleet of aerial tankers, aircraft that support combat bombers and fighters designated for both strategic and conventional missions. While the number and diversity of missions the tanker fleet might support are growing, budgetary pressures have already slowed the progress of modernization efforts. This study, undertaken at the request of the U.S. House of Representatives Committee on Appropriations, Subcommittee on Defense, examines the outlook for continued tanker modernization and improvement. While defense planning has come increasingly to rely on aerial refueling, the tanker fleet itself has diminished in size, from more than 800 aircraft over two decades ago to about 640 today. Furthermore, most of the aircraft in the present fleet are more than 20 years old and suffer from technological obsolescence. Awareness of these problems prompted Congressional action as early as 1979. Efforts to upgrade the tanker fleet are now under way and include the following approaches: (1) Modernizing existing KC-135As by replacing their aging J-57 engines with new CFM-56 engines, to produce KC-135R tankers; (2) Similar modernization of KC-135As, but with refurbished JT-3D engines salvaged from disused commercial planes, to produce KC-135E tankers (the source of JT-3D engines is commercially owned Boeing 707s, which are now being phased out because of new limits on air and noise pollution); and (3) Augmenting the fleet's capacity by procuring new KC-10 tanker/cargo aircraft. The continuing emphasis of the Administration's program for the tanker fleet has been on the first of these approaches. The second approach, mandated by the Congress, has been directed toward tankers in the Reserve forces. For the most part, KC-10s have been procured to expand capacity in the airlift fleet. This report compares these options in terms of capabilities and cost.