Abstract: The invention provides a refuel control system for controlling refuel of at least one tank (111,112,113, 14,115,116) onanaircraft 100,the refuel control system comprising monitoring apparatus (241, 242, 280, 371, 372, 380, 311, 312, 313, 314, 315, 316, 221) for monitoring data relevant to the refuel process, a control device (330) for receiving said data from the monitoring apparatus, and a refuel valve (130) for controlling flow of fuel to the tank wherein said refuel valve is controllable by the control device such that refuel of the tank can be controlled based on the monitored data. The invention also provides a method of refuelling at least one fuel tank on an aircraft.