[AERO PRB] MENDE (48) 12.09.1998 T2

GEIPAN continues to publish all its archives on www.geipan.fr. These include older cases originally classified A, B, C or D that are now being reassessed solely to improve the conclusions. New technical tools (software) and investigative experience gained over the years sometimes produce new observations or even a change in classification. This case, previously classified D and named [AERO PRB] from TOULOUSE (31) to DIJON (21) 12.09.1998, is among those recently reassessed. On 12 September 1998 at 21:46, an aircraft crew near the point directly above Mende (48) noticed 2 lights in the sky. In radio contact with the Marseille airport control tower, they reported 2 moving, flashing lights, initially taking them for 2 military aircraft one above the other. These aircraft passed them “well above.” At 21:54, the crew then reported “it is turning back towards us now,” followed by “we have really been observing the phenomenon for 10 minutes and it zigzags a little in all directions, it goes up and down.” Occupied with the detailed reporting procedure provided by air traffic control and then the descent procedure, the crew subsequently stopped mentioning the UAP. Only the radio-communication transcript and trajectory documents produced by the south-east air traffic control centre, CRNA Sud-Est, were collected. The recorded exchange divides into 2 phases, before and after the reported UAP turnaround. The investigation establishes that the pilots of flight PRB8081 first observed the anti-collision lights of 2 long-haul aircraft passing above them, which ground control could not then identify as such. Their trajectories could only be reconstructed later. It also establishes that the UAP or UAPs seen in the second phase could no longer have been those aircraft, whose lights were too distant to see. There were therefore 2 separate sightings. GEIPAN concludes that the first sighting concerned aircraft. The case [AERO PRB] MENDE (48) 12.09.1998 T1 is classified A: aircraft observation. At the reported turnaround at 21:54, the aircraft lights were at azimuth 70°, whereas the pilots described the observation at their 3 o’clock position, a difference stated as 20°. Another object probably became involved: Saturn, at azimuth 100° and an elevation slightly above 20°. Visually bright like the anti-collision lights, the planet was also approximately the same white colour. The pilots probably lost sight of the lights and may have thought they had found them again when they were actually seeing Saturn. They no longer mentioned flashing, which fits the hypothesis. This hypothesis nevertheless faces several objections and requires further examination: - It assumes the pilots had not previously noticed Saturn. While focused on the aircraft lights along azimuth 70°, they may have failed to notice Saturn 30° away in azimuth. When scanning more widely after the lights disappeared, they may not have recognised Saturn because they believed they were still seeing aircraft lights. This explanation requires a loss of sight of the lights before the Saturn misidentification: a break in observation neither confirmed nor ruled out by the recording. - The source states here that the pilots mentioned unusual movements as early as 21:46, when the 2 long-haul aircraft’s lights were no longer visible: “the phenomenon […] zigzags a little in all directions, it goes up and down.” This timing differs from the 21:54 transition described earlier. The amplitude of the movements is unknown. In the absence of such information, the account is compatible with the natural physiological effect of small eye movements, termed “micro-nystagmus” or the autokinetic effect in the source. Little known to the public, this occurs when staring at objects, particularly at night, and creates the false impression that luminous points make small erratic movements in all directions. - The pilots mentioned 2 lights but alternated this with references to a single point. They may have been uncertain, or actual perception of 1 point may have mingled with an interpretation shaped by the 2 unusual lights that had occupied their attention for over 10 minutes and had just been in the same direction. - The pilots continued observing until 22:04 and did not mention the UAP afterwards. That does not mean it was no longer visible: they were occupied first with the incident-reporting procedure and then landing. The case has poor evidential strength. In terms of information: - This is not 2 individual pilots’ witness accounts but a transcript of a real-time exchange with the crew, which does not distinguish each pilot’s perception. - No information was sought from the witnesses after the event, particularly about the most unusual points: the UAPs’ return, their number and changing appearance. Consequently, there is insufficient information about continuity of observation and changes in apparent sizes and angular positions, including the zigzags’ amplitude. In terms of reliability, the pilots had already spent 10 minutes in an air-incident situation, passing objects that control could not identify. Their tension would naturally have been heightened by a fatal mid-air collision 1½ months earlier involving an aircraft of the same airline. They were probably under considerable stress, encouraging them to maintain their interpretation of the initial objects and fail to recognise Saturn. A hypothesis could explain this second sighting, but its uncertainty is too great given the limited information and reliability of the available evidence. GEIPAN concludes that the second sighting cannot be meaningfully analysed for lack of reliable information. [AERO PRB] MENDE (48) 12.09.1998 T2 is classified C.