ROISSY-EN-FRANCE (95) 18.04.2016

On 18 April 2016 around 17:40, 2 witnesses at a bus stop saw an object rotating and glinting in the sky. Both described a square. T1 called its path straight; T2 described descent. T1 filmed it. T1 estimated 2 minutes and T2 13 minutes. Both thought of debris from an aircraft. No other accounts were collected. The investigation clarifies that 2 objects were observed. Strangeness is low, mainly the regular rotation about a transverse axis (see the investigation report). The abundant, detailed information has limited reliability because the witnesses themselves described poor viewing positions and sunlight preventing clear recognition, leaving only intermittent white flashes. These difficulties may also explain differing or contradictory trajectories. GEIPAN bases most analysis on the video of object 2, finding nothing in the statements to prevent the same explanation for object 1. Its physical appearance and movement resemble lightweight debris affected by gravity and rotation of unknown initial origin or caused by prevailing wind and local urban turbulence, combined with a favourable shape such as asymmetry or a propeller-like effect. Descent itself creates relative airflow that could cause or reinforce rotation, consistent with the witness’s drawn horizontal rotation axis. Rotation and induced lift and drag could also account for a 20–40° deviation from the wind’s direction. GEIPAN classifies the case B: probable lightweight debris of unknown origin.