3AF SIGMA2 is a technical commission of the Association Aéronautique et Astronautique de France (3AF) dedicated to the scientific study of UAP “hard observables” — physical evidence including radar tracks, sensor recordings, ground traces, and material samples. It has been led by luc-dini since 2013 and produces comprehensive technical reports on individual cases and methodology. It represents the engineering/aerospace-professional strand of French UAP research, distinct from the public-facing investigation of geipan.