The present paper describes the objectives, structure, present stage, results and future milestones of the project ELEVA. This project is aimed to control an autonomous helicopter in order to follow an overhead power cable by means of a stereo computer vision system. The helicopter is aimed to have always in sight the overhead power cable, to follow it by using it as an external visual reference guide and to record it for its ulterior visual inspection. These objectives are achieved by using a 3D computer vision system to generate the reference trajectory to be followed and by using internal sensors to control its stability and its trajectory. The paper presents the results obtained so far: visual detection and tracking of the power cable, robust under changing environments, and robust stationary control of the helicopter, now linked to a safety mechanical platform. Finally this paper describes the future challenges of the project and its temporal milestones.