Northrop flights prove software for autonomous refuelling

http://www.flightglobal.com/articles/2010/04/14/340613/northrop-flights-prove-software-for-autonomous-refuelling.html

Northrop Grumman has moved a step closer to achieving autonomous in-flight refuelling, which remains one of the major technology barriers facing unmanned aircraft systems.
A series of 10 test flights in March proved that a software algorithm based on relative navigation technology works inside an existing Northrop navigation system.