[AERO PRB] MENDE (48) 12.09.1998 T1

GEIPAN continues to publish all its 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 reexamined solely to improve the relevance of their conclusions. New technical tools (software) and investigative experience acquired over the intervening years sometimes lead to new comments or a change of classification. This sighting, previously classified D and named [AERO PRB] de TOULOUSE (31) vers DIJON (21) 12.09.1998, is one of a group of recently reexamined cases. On 12 September 1998 at 21:46, the crew of an aircraft near a position overhead Mende (48) noticed two intriguing points of light in the sky. In radio contact with Marseille airport's control tower, they reported two moving, flashing points, initially believed to be two military aircraft one above the other. These aircraft passed them 'well above'. At 21:54, the crew reported that 'it is turning back toward us now', then that 'the phenomenon has really been visible for ten minutes now and it zigzags a bit in every direction, going up and down'. Occupied by the detailed instructions from air traffic control for submitting a report, and then by their descent procedure, the crew subsequently stopped mentioning the UAP. Only a transcript of the radio communications and flight-path documentation prepared by the Southeast en-route air traffic control center were collected. The recorded exchange can be divided into two phases, before and after the reported UAP reversal. The investigation established that the pilots of flight PRB8081 initially saw the anti-collision lights of two long-haul aircraft passing above them, which ground control could not identify as such at the time. Their flight paths could only be reconstructed later. It was also established that the UAP or UAPs observed in the second phase could no longer have been those aircraft, whose lights had become too distant to see. There were therefore two separate observations. GEIPAN concludes that the first observation involved aircraft. Case [AERO PRB] MENDE (48) 12.09.1998 T1 is classified A: observation of aircraft. At the reported reversal at 21:54, the aircraft lights were at an azimuth of 70°, whereas the pilots described an observation at their three o'clock position, a difference of 20°. Another object probably then came into play: Saturn, at an azimuth of 100° and an elevation of just over 20°. Like the anti-collision lights, the planet was visually bright and approximately the same white color. The pilots probably lost sight of the lights and thought they had found them again when they were actually seeing Saturn. They no longer mentioned flashing, which is compatible with this hypothesis. However, the hypothesis raises several objections and points requiring further examination: - It assumes the pilots had not previously noticed Saturn. While the aircraft lights were visible at an azimuth of 70°, the pilots may have focused on them without noticing Saturn 30° away in azimuth. Once the lights disappeared, they may have searched more widely and failed to recognize Saturn because they were convinced they were seeing aircraft lights. This explanation requires the lights to have been lost before Saturn was misidentified: a break in the observation that the recording neither establishes nor rules out. - The source says that the pilots mentioned unusual movements as early as 21:46, when the two long-haul aircraft's lights were no longer visible: 'the phenomenon [...] zigzags a bit in every direction, going up and down'. This time conflicts with the earlier sequence, which puts the initial aircraft-light observation at 21:46 and the reversal report at 21:54. The amplitude of these movements is unknown. In the absence of that information, the investigation considers them compatible with the natural physiological effect of tiny eye movements ('micro-nystagmus'), also called the autokinetic effect. The source describes this little-known effect as occurring when a person stares at objects, particularly at night, creating the false impression that point-like lights make small erratic movements in every direction. - The pilots mentioned two points of light, alternating with references to a single point. They may have been uncertain, or their actual perception of one point may have become mixed with an interpretation based on the two strange points that had occupied them for more than ten minutes and had just been in that direction. - The pilots continued observing until 22:04 and did not mention the UAP afterward. This does not establish that it was no longer visible: they were occupied first with the incident-reporting procedure and then with landing. The case is poorly substantiated. Regarding information: - The material is not two individual pilot accounts, but a transcript of a real-time exchange with the crew that does not distinguish what each pilot perceived. - No information was sought from the witnesses afterward, once removed from the immediate situation, particularly about the strangest features: the UAPs' return, their number and their changing appearance. Information is therefore lacking on whether the observation was continuous and on changes in angular size and position, including the amplitude of the zigzags. Regarding reliability: - The pilots had already spent ten minutes in an air-incident situation, passing objects that control did not identify. The investigation considers that tension would naturally have been heightened by a fatal midair collision involving an aircraft from the same company a month and a half earlier. The pilots were probably under considerable stress, contributing to their continuing to interpret the observation as the original objects and failing to recognize Saturn. There is a hypothesis that could explain the second observation, but its uncertainty is too great given the limited evidential strength of the available information and its reliability. GEIPAN concludes that the second observation cannot be analyzed because reliable information is lacking. Case [AERO PRB] MENDE (48) 12.09.1998 T2 is classified C.