[AERO] de LOS ANGELES (US.90045) vers ROISSY-EN-FRANCE (95) 16.12.2025

On December 16, 2025, at 08:50 UTC (09:50 CET), an aircrew member in the cockpit of an aircraft connecting Los Angeles to Paris observed a luminous phenomenon on the right of the aircraft. At that time, the aircraft was flying at FL350, over the North Atlantic, south of Greenland. The phenomenon was initially manifested as a white light point evoking a satellite, moving on a straight and slightly descending trajectory, from azimuth 120° to azimuth 90°. After a few tens of seconds, this point suddenly turned into an intense white light, described as a static "explosion", and then into a diffuse spot with purple pink hues that gradually spreads before disappearing. The total sequence lasted about three minutes. A second witness, present in the cockpit, confirmed the observation. The case has good evidential quality. The testimony is from an observer experienced in the aeronautical field, it was transmitted the day after the observation by means of a detailed technical questionnaire, then completed by cognitive interview. A second direct witness is mentioned, but only 1 questionnaire was completed. The file does not contain instrumental recording or reconstruction. *According to the GEIPAN criteria, evidential quality is the amount of information collected for an account that is considered reliable and objectively established. The strangeness reported by the witness is mainly due to the succession of three phases: initial movement resembling a satellite’s, followed by a static luminous "explosion", and then the formation of a diffuse and coloured halo that gradually extends. The absence of noise, the suddenness of this transformation and the atypical aspect of the diffuse phase justify the perception of an abnormal phenomenon. The following points are established by various investigations (detailed in the investigation report): the aeronautical data confirm that the aircraft was operating at night in VMC conditions south of Greenland. The astronomical analysis excludes the Moon and the bright stars present in this area. Although a satellite was identified in the area during this time interval, its ascending trajectory is incompatible with the observed dynamics; moreover, this hypothesis does not allow the phases of static "explosion" and coloured diffusion to be explained. The launch of an Atlas V 551 rocket from Cape Canaveral at 08:28 UTC, 22 minutes before the observation, provides a consistent explanation. At 08:50 UTC, the Centaur stage reached the engine cut-off phase (MECO-1), followed by planned venting. GEIPAN considers this sequence to explain the entire phenomenon: the moving luminous point corresponds to the stage in flight, the apparent sudden "explosion" is linked to the degassing (venting), and the diffuse halo results from the illumination of the gas cloud by the Sun, then located at a 92° azimut but at an elevation of −26°, below the horizon. The strangeness of the case is thus greatly reduced. GEIPAN attributes the phenomenon’s spectacular appearance to the observation geometry and illumination of the gas cloud by the Sun below the horizon, giving the illusion of a static explosion during a nominal stage of the Centaur flight. The observation corresponds to the flight sequence of the Centaur stage of the Atlas V 551 launcher, including the engine shutdown (MECO-1) and the associated planned venting. GEIPAN classifies the case as "A" observation of the Centaur second stage of an Atlas V 551 rocket.