This paper presents real-time results of a decentralised airborne data fusion system tracking multiple ground based targets. These target estimates are then used to construct a composite map of the environment. A decentralised communication strategy which is robust to communication latencies and dropouts results in each sensing node having a local estimate using global information. In addition, this paper describes the hardware and algorithms for the sensing nodes used in this demonstration. The problems introduced by locating the sensing nodes on air vehicles are both interesting and challenging.