A triangle shape in Seine-Saint-Denis, France

On May 4, 2015 (the witness confirms the date) at around 4 a.m., a witness waking up is intrigued by the passage in the sky of a triangular shape suggested by the presence of lights at the corners. The object passes at a right angle in front of his terrace, at the height of an aircraft flying at low altitude. The witness hears the noise of an aircraft flying at low altitude. No other testimony is collected. This observation case describes a phenomenon having many characteristics of an aircraft: fixed white-yellow lights, and flashing red and white lights, apparent size and noise. But the witness, who does not distinguish any fuselage or wings, gives it a triangular shape, which makes him find this craft strange. When an observer sees a set of luminous points, it is common for him to interpret this set of points as an object simply bounded by these luminous points. This illusion, called shape or contour illusion, occurs on lights independent of each other (case of Thai lanterns) and also on aircraft in cases where the wings are poorly visible: the witness then reconstructs a black volume bounded by the visible lights. If the witness did not see the wings or fuselage of the aircraft, it may be because his viewing angle did not allow it (wings seen edge-on), or more probably because the aircraft itself was very dark in color, as are for example large military transport aircraft. The axis of one of the runways of Le Bourget airfield passes directly through Epinay-sur-Seine (7.5 km away). The Météociel report notes a southwest wind recorded at Roissy: aircraft therefore take off toward the west in the direction of Epinay (see the Météociel report. GEIPAN classifies this case in category B: probable observation of an aircraft. Unfortunately GEIPAN did not process this observation case quickly enough to be able to check with air traffic control whether there had indeed been a flight at that time.