Sighting in La Saulce, December 8, 2019

The witness saw two black trails in the sky that looked vertical and moved slowly. The sighting lasted about thirty minutes, starting around 4:30 pm according to the witness, as the sun was about to set. The witness first thought of aircraft trails with a lighting effect, and took several photos using the zoom. What puzzled them was that no aircraft showed up in the zoomed images and that the phenomenon gave an impression of falling. They then considered a plane crashing, a meteorite or a piece of rocket debris. Theirs was the only account collected.

The investigation concluded that the witness had mistaken aircraft contrails, seen along their line of sight shortly after sunset. Depending on weather and astronomical conditions, contrails can look striking and can persist long after the aircraft has passed. The black colour, while still clearly visible, is explained by twilight: how much light a contrail receives depends on the position of the terminator. The shape, two broken parallel lines that distort with the winds at altitude and meet where the aircraft is, can be seen in the photos. The aircraft may no longer be visible, either because the setting sun no longer lights it or because it is already far away. Through perspective, a plane heading toward the horizon along the witness's line of sight creates the illusion of a vertical descent, although it keeps its altitude.

The specific aircraft could not be identified with certainty, because the exact time of the sighting could not be determined: the witness said about 4:30 pm, the photos are timestamped 6:21 pm, and sunset, checked with Stellarium, was at 6:54 pm (local time). Flightradar shows several possible aircraft between 4:30 and 7:00 pm in the direction observed, the south-west. GEIPAN classified the case as A, with a very high probability of contrails.