[AERO LOC] MARCK (62) 09.12.2002

GEIPAN continues to publish its complete archives on its public website, www.geipan.fr. These include older cases classified at the time as A, B, C or D that are now being re-examined solely to improve the conclusions. New technical tools (software) and the investigative experience acquired over the intervening years sometimes allow this re-examination to produce new observations or even a change in classification. This case of observation previously classified D and called GRAVELINES (59) 2002 is part of a recently reviewed set of cases. On December 09, 2002, at about 10:45 a.m., an instructor pilot was in flight with two students. While taking off from Calais-Dunkerque airfield (commune of Marck (62)), they were surprised to see, for less than 10 seconds, a luminous phenomenon of circular form that was heading towards them before changing direction and disappearing from their sight. The UAP colour was first described as yellow white and then metallic grey. The instructor pilot was surprised because this object had not made any manoeuvres to move away. The Lille-Lesquin control tower contacted immediately did not notice any aircraft on radar screens. The instructor pilot contacted the Gendarmerie at about 5:00 p.m. to know if other people had seen the phenomenon: apart from the instructor pilot and his two students, no further testimony was collected. Witnesses probably observed sunlight reflected from an airliner passing about 20 km away (probably the Brussels-London line). Indeed (see investigation report): - the aspect described (color, shape) is compatible and the pilot instructor thinks of this hypothesis and rejects it only because he believes the necessary conditions, particularly the Sun’s position, were not met; - the respective position of the witnesses and the sun explains a specular reflection on an aircraft fuselage oriented to act as a mirror on the London-Brussels line crossing 20 km from the witnesses; - the specular reflection condition (and therefore sensitive to geometry) explains the short duration of the UAP; - the witnesses perceive the disappearance of the UAP by recession into the distance, which corresponds to a classical illusion. Indeed, when the luminous intensity of a UAP decreases, it is logical for a witness to interpret this as recession into the distance of a UAP that would have kept the same luminous intensity. The only uncertainty on the hypothesis is that: - the phenomenon of specular reflection on an aircraft fuselage is known to occur but has not been modeled in a way that quantitatively validates its brightness or how that brightness changes over time; - there is no evidence of aircraft presence, but this is not determinative because the records are unavailable 17 years later. The foregoing factors affect only the probability of the hypothesis, which remains very plausible. The evidential quality is good (several witnesses, sketches, position indications). Consequently, GEIPAN concludes in B: probable observation of an airliner (reflected light).