PLAISIR (78) 12.04.2015

Between 13:30 and 14:15 on 12 April 2015, a witness on a terrace in Plaisir (78) was watching aircraft high in the sky when he saw a dark, flattened-lens-shaped object moving very fast at low altitude on a straight path. The landscape eventually hid it. Only 1 account was collected. GEIPAN requested a radar traffic record from military air traffic control. Tracks overlaid on Google Earth with accuracy of roughly 500 m showed considerable small-aircraft traffic under visual flight rules (VFR). One track fitted the observation fairly well: the red track on the radar map crossing Plaisir east to west from 12:10:48 UTC, about 14:10 local time, to 12:12:18 UTC. It climbed slowly from 400 m (Z12) to 500 m (Z16), travelling at around 160 km/h, with source speeds of 89–75 knots. It would have passed the witness in less than 1 minute, compared with his stated 30-second sighting. GEIPAN explains that this probably small aircraft seemed farther away and therefore faster than it really was. Looking south near solar noon, the witness saw it against the light, making it appear black. At low angular elevation, edge-on wings could be invisible. GEIPAN classified the case B: probable observation of a small aircraft flying visually at low altitude, backlit by the Sun. Uncertainty about the sighting time prevented a class A identification.