An account in Jura, France

GEIPAN continues to publish all of its archives on its public website www.geipan.fr. Among its publications are old cases classified at the time (A, B, C or D) which are now being re-examined, for the sole purpose of being more relevant in their conclusions. Thanks to new technical means (software) and the investigation experience acquired over all these recent years, this re-examination sometimes leads to new remarks or even a change of classification. This observation case, previously classified D and named ROUSSES (LES) 11.08.1988, is part of a set of cases recently re-examined. It concerns the observation of the movements of an UAP with intermittent flashes by two witnesses, on 11 August 1988 around 00:50. Trainee military personnel, they were bivouacking at a place called "le chalet de Bonnefoy" in the forest known as "Risoux" in the municipality of MOREZ (39). The witnesses were first intrigued by the presence of white flashes in the night sky, then by the speed and particular trajectory of the UAP as well as the absence of noise. The UAP, described as an elongated shape, disappeared from their view by taking a descending trajectory and being hidden by the landscape. The Gendarmerie, alerted, collected no other testimony about this phenomenon during its investigation. The points of strangeness noted by the witnesses during their observation can all be explained by a simple confusion with an aircraft and its anticollision lights observed under particular conditions. The speed of the UAP, described as "greater than that of a Mirage type F1" by T1, is in reality particularly difficult, even impossible, to assess at night, without any fixed reference point and without knowing the altitude of the UAP's movement, even for a witness claiming "to be used to seeing Mirages flying". The perception of noise is also highly dependent on other factors, unknown in the present case, such as the distance separating the witnesses from the UAP, the sound environment, the witnesses' own auditory perception, the sound power emitted by the UAP, and the strength and direction of the wind. There are many confirmed cases in the GEIPAN archives (including with radar proof) of observations of aircraft without noise perception. Also, for lack of details on these parameters, the absence of noise perception is not decisive. T1 also states that the lights were "too intense" to be those of an aircraft. However, we are in a particular and unusual observation configuration for the witnesses. Indeed, they find themselves in a temporary nighttime observation situation, in the forest, far from any light pollution and parasitic lights, whereas they usually reside in built-up areas. Moreover, having been outside for several hours, their night vision has had ample time to adapt to the environment, which is particularly dark. As a result, any strong light, even distant, will appear to them as being very intense. Another aspect of strangeness for the witnesses, and in particular for T1, is the impression that the UAP was moving in a "sinusoidal" manner. The fact that T2 states that the UAP was moving along a "straight line" and that "the flight path was irregular, it [this shape] went up and down always quite quickly", gives us clues about what T1 perceived and about the nature of the UAP's actual movement. The rapid alternation of anticollision lights placed at distant points on the aircraft and the impossibility at night of perceiving the aircraft's shape can, from a favorable observation angle, create a perceptual illusion of rapid sinusoidal movement coming from the lights alone, while the movement is of course rectilinear. This can be observed in videos accessible on the internet. The last point of strangeness noted by the witnesses concerns the apparent stop, then the descent "toward the ground" of the UAP. This is easily explained by a temporary gain in altitude of the aircraft in a movement occurring along the observation axis, which produces an effect of apparent immobility. Once the aircraft reaches its altitude level, the observation angle decreases again until the aircraft disappears behind the trees. Moreover, the strong brightness of the aircraft's anticollision lights, perceptible from very far away, reinforces the impression that it remains relatively close; consequently, this final observation phase is interpreted by the witnesses as a "descent", whereas it is in reality a moving away. The plausibility of an aircraft at that place and time, apart from the compatibility with the observation as assessed above, is good. There are 5 airports within a 120 km radius of the location, including 4 international and one military. An aircraft coming from one of these airports is not yet at cruising altitude and can therefore create the illusions explained with its various lights and its altitude changes. The consistency is mediocre. All useful angular data are absent (dimensions of the UAP, initial and final elevation above the horizon). The temporal data are imprecise, or even also absent. Consequently, GEIPAN classifies the case as B: observation of an aircraft.