Air to air refuelling was pioneered by Great Britain during the early 1930s. It has now been developed to the point where it happens with many Air Forces on a daily, routine basis and is essential in extending the range of some military aircraft in order to complete their mission. The most complex air refuelling mission ever accomplished was that of the Vulcan bomber which bombed the runway at Port Stanley in The Falkland Islands. This consisted of a relay of Victor tankers refuelling each other to extend their range so that one could provide sufficient fuel to the Vulcan to get to its destination and then further Victors refuelling each other to pick up the Vulcan on its return. As an exercise in military planning it was an exceptional piece of work.
The aircraft seen here is a USAF F-4E Phantom which was refuelling over Germany in 1983. The tanker was a KC-10, converted from a civilian DC-10 aircraft.