BRON (69) 26.11.2013

On Tuesday 26 November 2013 at about 17:30, a witness in Bron noticed 4 unusually shaped luminous forms apparently stationary in the western evening sky. GEIPAN considers their oblong appearance in the photograph strongly suggestive of aircraft contrails illuminated by the Sun after sunset. The Sun had set at 17:00 at azimuth 240°, between southwest and west. A Flightradar record shows a candidate aircraft for the trail. Referring to its information on unusual-looking contrails, GEIPAN explains that trails can be seen from nearly 80 km away in clear weather. At that distance, an aircraft's angular movement looks very small, especially when approaching or receding. Once the Sun drops too far below the horizon, the unlit trails become invisible. The case is classified A: aircraft contrails.