Automatic guidance of flying vehicle usually needs external information. GPS (Global Positionning System) is a worldwide technology which provides to the guided system its deviations with respect to its guidance objective. Nevertheless, this technology is not available everywhere (indoor evironment), everytime (in case of failure) and not precise enough to ensure critical operations as landing a civil aircraft. Current civil aircraft are able to land autonomously on a runway thanks to ILS (Instrument Landing System) or differential GPS. However, these equipment are expensive and can fail. In frame of the future aircraft, manufacturers like AIRBUS company study the possibility to make aircraft landing everywhere (unequipped or unknown runway) without using informations from external systems.