The number of offshore windmills is increasing across the oceans and seas, for whose appropriate localization companies need to measure the environmental conditions at different spots over the see. The met masts developed by APIAXXI are the perfect structures to get this information, but also these structures need to be inspected and maintained. During the last two months a sophisticated autonomous flying prototype was design by Skybotix. On board this advanced aircraft will be working novel approaches of autonomous avoiding collision algorithms and visual inspection systems developed by CVG-UPM. The masts of more than 90 meters move without control under the chaotic commands of waves and wind in the Cantabrian Sea. To create a met mast inspection demonstrator a group of experts from APIAXXI were measuring the environmental conditions and the movements of these large structures.