COLMAR (68) 21.08.2015

On 21 August 2015 at 11:05, a man and his wife were at Colmar airfield, waiting for their daughter to make a parachute jump. They saw a pale white ball cross the sky from north toward northwest, apparently faster than the aircraft being used for the jumps. The phenomenon ended abruptly toward the Vosges; the source summary describes a sudden disappearance. The man mentioned it to the person who had jumped with his daughter, who had seen nothing. Only one account was collected. GEIPAN's analysis records the following observation conditions: - The witnesses were stationary outdoors on the airfield tarmac, in an open area north of Colmar. - There was one pale white, round light with blurred edges, an estimated angular size of 1°, and no sound or trail. It was first seen to the north and disappeared to the northwest. The witness's indications were used to reconstruct straight movement on a heading of 220°, at 4°/s. Its elevation fell from 40° to 20°; whether this reflected increasing distance, an actual descent, or both was unknown. - Meteociel data for Colmar airport at 11:00 show a light easterly wind averaging 6 km/h and no precipitation. The witness described a perfectly clear, blue, sunny sky. - It was a Friday in the late morning. The plotted trajectory appears in “carte report trajectoire.jpg”. GEIPAN first considers sunlight reflected from a flying object's metal surface or canopy. The ephemerides place the Sun at azimuth 127° (southeast) and elevation 43° at 11:05; see “Éphémérides Soleil.jpg”. The source describes the observed north-to-northwest path, reconstructed at 220° with elevation falling from 40° to 20°, as diametrically opposite the Sun. These source bearings and geometric descriptions are retained without reconciling them. “Hyp Carte reflet soleil.jpg” plots the elements. The analysis states that sunlight was incident almost perpendicular to the path, while the Sun's 43° elevation was comparable to the initially estimated 40° elevation of the phenomenon. It considers these conditions favorable for a reflection, as illustrated in “Hyp Géométrie reflet soleil.jpg”. The light would disappear when the angles between Sun, object and ground observer ceased to favor reflection. GEIPAN uses this geometry to explain why parachutists at different heights and locations did not see it: visibility required a particular position at that moment. It then examines 3 possible sources of the reflection. Hypothesis A: a civilian aircraft approaching Basel-Mulhouse airport. The reconstructed path could fit an aircraft turning to line up with the airport's runway. The airport is 55 km away to the south, at bearing 170°, with a runway heading of 150°. “Hyp A approche Bâle-Mulhouse.jpg” shows the reported path in red, the runway in blue and an interpolated connection to landing in black. Sunlight could reflect from a fuselage following a curved path around the observer, then disappear as the aircraft straightened onto the runway alignment. The source describes approaches near Colmar at 10,000–12,000 feet, or 3,000–3,600 m, and 300–400 knots, which it gives as 600–700 km/h. The witness's estimate of 60° in 15 seconds yields approximately 4°/s. Assuming an aircraft at 3,000–3,600 m altitude and 43° elevation, the source uses a distance of 3,000–3,600 m. Its calculation at 3,000 m is 3000 × tan(4°) ≈ 200 m/s, or 720 km/h; at 3,600 m it gives 860 km/h. These are the source's estimates and conversions. It finds the hypothesis credible if the witness underestimated distance: around 3,500 m rather than half that distance, implying about 800 km/h, considered compatible with an approach that far from the runway. Civilian radar records, however, show no aircraft following that path at that time. Flight AB7653 was present, but on the opposite heading, 038°; the source notes 038° + 180° = 218°, approximately 220°. It was approaching Baden-Baden, 90 km away to the northeast at bearing 035°, with runway heading 030°. Its ground track passed 1.3 km northwest of the witness, at an altitude of 4,000 m, giving an elevation of about 70°. GEIPAN considers this unsuitable for the proposed reflection, even if the witness had reversed the movement direction in the questionnaire. The radar plot is in “Hyp Abis approche réelle Baden-Baden.jpg”. Hypothesis B: a military aircraft approaching Air Base 116, Luxeuil-Saint-Sauveur. The source describes the base as home to the 2nd Fighter Wing, with a single flying unit, Fighter Squadron 1/2 “Cigognes”, operating Mirage 2000-5F aircraft. The base is 80 km from the witness at bearing 250°, with its runway aligned at 290°. An aircraft passing Colmar to land there would need a heading farther south than 250°, compatible with the observed 220°, before turning westward onto 290° to align with the runway. In this scenario, the reflection would come from the cockpit canopy as the aircraft banked slightly toward the observer along a curved path. The source states that the airframe was treated for concealment. “Hyp B Verrière mirage 2000.jpg” illustrates the canopy's size. A request for military-traffic information absent from the civilian radar records was made in May 2017. No reply was received, so this hypothesis could not be verified. Hypothesis C: a daytime Iridium flare. The source states that celestial objects can be seen with the naked eye by day when their magnitude is below −4, citing Venus near maximum elongation and describing this as little known to the public. It gives Iridium flares as bright as magnitude −8, described as nearly 30 times Venus's brightness, allowing some to be visible by day. It also states that, despite the Sun's yellow colour, objects visible in the daytime sky appear white, citing the Moon near its quarter phase. These are the source's explanatory claims. An Iridium flare is considered plausible, but the required ephemerides for that date and place were no longer available to confirm it. GEIPAN assesses the account as having good evidential support, referring to several witnesses but one statement and reliable information. Without a reply from the military authorities, certainty is unavailable. It favors a military aircraft approaching Air Base 116 as the most probable explanation and proposes classification B: probable sunlight reflected from a military aircraft's canopy.