The German air force has received the first of four Airbus 310 air transports that have been converted to serve as aerial tankers. In addition to the four produced for Germany,  two more are being built for the Canadian air force. The A310 tanker is a twin engine aircraft that can carry 77 tons of fuel, with 40 tons available for transfer in the air. The aircraft can refuel two other aircraft at once, transferring nearly three tons of fuel a minute to each aircraft. The U.S. four engine KC-135 carries 90 tons of fuel and can transfer up to 68 tons.