Sighting in Brioude, September 20, 1956

Two pilots flying in a patrol saw a spherical, aluminium-coloured object moving at about 15:50. Intrigued, they tried to get closer and climbed, but found they could not reach it. They gave up the chase at 16:10.

Investigators contacted the director of the Puy-de-Dôme observatory in Clermont-Ferrand. The director reported that a translucent, roughly spherical balloon with a slight bulge at its base had been seen in the sky over Clermont throughout 20 September. It drifted steadily and very slowly at about 20 km altitude, then became invisible at 19:05 when the sun no longer lit it. The observatory did not know where the balloon came from: neither it nor the regional weather services had released one.

GEIPAN classified the case as B: a probable stratospheric balloon whose origin was never found. The impression of being followed by the object and the impossibility of getting closer are typical perceptual illusions when viewing a distant object. Here, the very large balloon was about 17 km from the pilots. Climbing to 32,000 feet (10,000 metres) brought that distance down to only about 10 km, which was still considerable.