Sighting in Étrépagny, January 4, 2015

At about 7:45 pm, a passenger on a scheduled flight noticed a light on the ground moving at the same speed as the aircraft. Other passengers, asked to look, saw it too. The plane was approaching the outskirts of Paris at the time. In a phone interview, the witness placed the phenomenon to the left of the aircraft, at an angle of between 50° and 70° from the vertical. At times it appeared ahead of the plane and at times behind it, which sometimes forced the witness to turn their head backward. They also described filaments.

The investigation noted that the Moon, 99.6% full, lay due east, at an azimuth of 90.8° and an elevation of 23.26°, so it was within the witness's field of view. The witness did not mention it, probably because their gaze was fixed on the ground. Since the light seemed to follow the aircraft, an optical effect involving a celestial body was favored from the start. GEIPAN considers it very likely that the light was the Moon's reflection on lakes and flooded areas, which stood out against the dark ground. The filaments were probably flooded paths or small canals. Rain had been recorded across the northern half of France on 2 and 3 February. The witness's estimated angle fits this explanation, since it should ideally be 67°, the complement of 23°. The shifts between ahead and behind result from the plane's changes of heading, the reflection always lying due east. GEIPAN did not have the information needed to match the plane's exact route with the apparent position of the phenomenon. The case is classified B: very probable reflections of the Moon on bodies of water and flooded areas.