KC-46 Tanker Aircraft: Acquisition Plans Have Good Features but Contain Schedule Risk

Abstract : While several types of aircraft provide aerial refueling services, the principal effort is currently carried out by the Air Force fleet of 414 KC-135 aircraft. Originally fielded in the 1950s, KC-135 aircraft are considered the mainstay of the tanker fleet, supporting combat air assets, deployment of airlift aircraft, and nuclear combat refueling missions. With an average age of nearly 51 years and more than 16,000 flight hours on each aircraft, the KC-135s will approach over 80 years of age when the fleet is retired as projected in the 2040 time frame. In 1981, the Air Force began supplementing its fleet of KC-135s with the procurement of 60 KC-10s (of which 59 remain in service today), multi-role aircraft that transport air cargo and provide refueling. Much larger than the KC-135, the KC-10 provides both boom and hose and drogue refueling capabilities4 4Currently, Air Force fixed-wing aircraft refuel with the flying boom. The boom is a rigid, telescoping tube that an operator on the tanker aircraft extends and inserts into a receptacle on the aircraft being refueled. Air Force helicopters, and all Navy and Marine Corps aircraft refuel using the hose and drogue. The hose and drogue system involves a long, flexible refueling hose stabilized by a drogue (a small windsock) at the end of the hose. on the same flight and can conduct transoceanic missions. The KC-10s now average about 27 years of age with more than 26,000 flight hours on each, and their service life is expected to end around 2045. The Air Force has upgraded and modified both fleets in recent years, providing improved avionics and new engines on the KC-135 along with newer communication systems to comply with international and federal air traffic requirements.