Sighting in Échirolles, July 29, 2024

At around 6:30 a.m., two witnesses were outdoors when they noticed a white point of light to the west. It moved slowly and steadily from south to north, at a roughly constant elevation of about 60° above the horizon. No sound was heard. After about five minutes, the phenomenon disappeared toward the northwest, hidden by nearby vegetation. One of the witnesses filmed it, and the 44-second video was recovered and analysed. Only one of the two witnesses completed a questionnaire, but the account was judged to be of satisfactory consistency.

The investigation looked at two explanations: an aircraft and a cluster of balloons. An aircraft initially matched several features (elongated shape, white colour, steady straight path), but it was considered unlikely because no such aircraft appeared on radar maps. The balloon cluster was judged more plausible: an elongated overall shape containing distinct round elements, a bright white colour from balloons lit by the just-risen Sun, and a slow, steady, straight movement typical of objects carried by the wind. Measurements taken from the video were consistent with a group of balloons about 80 cm to 1 m long, located roughly 40 to 70 m from the witnesses. Wind was highly variable, with shear between the ground and 500 m altitude. A south-to-north wind in that area was therefore possible, but could not be demonstrated. GEIPAN classified the case as B: probable observation of a cluster of balloons.