Aircraft and intermittent light in Tourdun in 2018

Summary

A long-exposure photograph taken in April 2018, aimed at the zenith between Ursa Major and Leo, captured a luminous trail the witness initially assumed was a conventional aircraft. What puzzled him was an intermittent illumination of the ground, pulsing every two seconds, that he noticed during the observation. GEIPAN identified the trail as an Airbus A321 on the Munich–Lisbon route using stellar calibration, though the anti-collision light sequence was abnormal, attributed to an equipment malfunction on the aircraft.

The witness's description of the ground light was self-contradictory, suggesting a perceptual distortion. Investigators pointed to a priming effect: initial surprise at something unexpected can lead the observer to notice details that would otherwise go unregistered. The fleeting light appeared in peripheral vision, consistent with a local source such as car headlights. With the photographic trajectory firmly established, the case was classified as A — fully explained.