The IBC (Knowledge Base Integration) project addresses an issue of ontology-based data integration. It aims at combining data residing in different actors (aircraft, drone, satellite...) during an air mission scenario and providing users with a unified view of all available data, in a communication constrained environment. We describe the solution we have implemented based on mediation. We use rule languages to process queries using an OWL2 domain ontology and RDF triples to store data. We also give a performance analysis of our prototype.