Sighting in Nantes, August 13, 2013

A passenger on a Nantes–Rome flight was looking out of the left side of the aircraft when they noticed, several kilometres away, a vertical black shape sticking up above the clouds. The witness described it as matt black and shaped like the tail fin of an aircraft. It seemed to hang motionless. It then tilted to the horizontal and took on the look of a very thin black saucer. It vanished after about a minute, though the witness had time to photograph it. They estimated it to be very large, perhaps three times the size of an airliner or more. The passenger in the next seat also saw it but did not wish to give a statement, and no one on board spoke with other passengers during the flight.

The case therefore rests on a single testimony, which an investigator's interview found reliable. The photos were taken from too far away to show the phenomenon clearly. GEIPAN ruled out several explanations: a cloud (a compact black mass that slowly rotated on its axis), an aircraft or drone (estimated size far too large, no wings), a balloon or airship (it stayed stationary at airliner altitude, between 10,000 and 12,000 m), atmospheric re-entry (constant altitude), a celestial body (clear blue sky), and the aircraft's shadow on the clouds. Because estimates of size and distance are very uncertain, the case remains strongly unusual, but the data are insufficient to settle its origin. GEIPAN classed it as category C.