Sighting in Longueville, March 5, 2015

A witness was at a railway station at about 7:13 a.m. when they noticed a trail in the sky with an unusual zig-zag shape. They took a photograph, which the GEIPAN then submitted to experts at Météo-France.

The experts confirmed it was a condensation trail that had been distorted after forming, by turbulence at the altitude where it was created. They explained that very agitated zones can exist in clear skies ("clear-air turbulence"). Pilots dread them because they are hard to predict, invisible on radar and the site of violent phenomena, which sometimes force crews to change flight level to keep passengers comfortable. The experts added that they had never before seen a photograph with such pronounced sinuous curves.

The case was classified A. The trail came from an Airbus A319 operating flight AF7614 from Marseille to Lille, whose position at 7:13 a.m. local time appears on a Flightradar record. The contrail had been strongly disturbed by atmospheric turbulence. The file also includes a ground-level Météociel record from Melun.