LOUVIERS (27) 17.09.2017

On 17 September 2017 between 22:00 and 23:00, a witness lay on a mattress on the floor of his top-floor flat in a built-up area, looking at the sky through a window. He saw 3 faint lights arranged in a triangle and found their appearance unusual. The outline of a dark triangular object then stood out against a cloud. As the UAP was about to leave the window’s field of view, he got up to open the window. The passage was silent and straight. It quickly disappeared behind his building’s roof. The sighting lasted under 10 seconds. Only 1 account was collected. The investigator considered these objective elements: a dark night, scattered clouds and light-to-moderate wind; a brief observation, listed as 10 seconds in the analysis; several faint yellow-orange glows and a dark mass; and a region with dense civilian and military aviation at the intersection of air routes. The favoured candidates were misidentifications of sky lanterns, civilian or military aircraft, or civilian or military drones (see the investigation report). The main support for sky lanterns is the appearance of several faint lights moving together, perceived as a single object, a pattern typical of lantern-release accounts. Although partly compatible with the description, this explanation was not judged probable because the wind opposed the UAP’s trajectory. Aircraft were considered because of the heavy aviation activity and nearby military airbase. A civilian aircraft was ruled out: the viewing angle from the window offered a poor view of the existing air route, and aircraft on radar were in the wrong direction. A military aircraft on a training flight from the base south of Louviers, at very low altitude and outside radar detection, might explain the faint lights in an unusual triangular arrangement. However, with the window open the witness should have heard its engines, and no military flight from the base was confirmed. This hypothesis was therefore not judged probable. The investigator’s final candidate was a civilian or military drone. The variety of drone shapes, sizes and appearances could account for something unfamiliar to a witness accustomed to aircraft overhead. Its south-to-north direction might suggest departure from the military base south of Louviers. However, the lack of an authorised flight area nearby, particularly for night operations, weakens this possibility. No drone flight from the base was confirmed either. The straight, constant-speed trajectory is ordinary. The appearance—3 faint triangularly arranged glows around a dark central mass—nevertheless strongly puzzled the witness and remains unexplained by the considered hypotheses. Without another account, photographs, video or a more precise time, further analysis is not possible. The case is classified C: insufficient reliable information.