Aerial refueling, also referred to as air refueling, in-flight refueling (IFR), air-to-air refueling (AAR), and tanking, is the process of transferring fuel from one aircraft (the tanker) to another (the receiver) during flight.
The procedure allows the receiving aircraft to remain airborne longer, extending its range or loiter time on station. A series of air refuelings can give range limited only by crew fatigue and engineering factors such as engine oil consumption. Because the receiver aircraft can be topped up with extra fuel in the air, air refueling can allow a takeoff with a greater payload which could be weapons, cargo, or personnel: the maximum take-off weight is maintained by carrying less fuel and topping up once airborne. Alternatively, a shorter take-off roll can be achieved because take-off can be at a lighter weight before refueling once airborne. Aerial refueling has also been considered as a means to reduce fuel consumption on long distance flights greater than 3,000 nautical miles (5,600 km; 3,500 mi). Potential fuel savings in the range of 35-40% have been estimated for long haul flights (including the fuel used during the tanker missions).