[AERO EZY] DROME (26) 29.03.2019

On 29 March 2019, during EasyJet flight EZY926L from Lille (59) to Nice (06), the pilot contacted air traffic control about wake turbulence and possible “heavy” traffic—a large aircraft—1,000 ft below. He said a heavy aircraft had crossed right to left a few minutes earlier and asked what type it might have been because its lights were “fairly unusual.” Two people had seen the lights. The UAP also appeared on the onboard TCAS, but no aircraft matching its described altitude and path appeared on the Aix-en-Provence control center's radars. The account rests on aircraft–controller exchanges; no other testimony was collected. The investigation report summarizes those exchanges as follows: - At the NISAR reporting point, the pilot reported wake turbulence that he associated with the heavy aircraft seen a few minutes earlier (see report appendix). - Before reaching NISAR, the crew had seen an aircraft with unusual lights from the cockpit. The TCAS target was about 10–15 nautical miles (20–30 km) ahead and 1,000 ft (300 m) below, moving right to left on a heading the pilot estimated as 060°. - No aircraft matching that path and altitude appeared on the Aix-en-Provence control center's radars. TCAS is an onboard collision-avoidance instrument that detects nearby aircraft equipped with operating transponders. It is not radar and does not detect aircraft without transponders or with them switched off. A transponder is an electronic device allowing an aircraft to be identified by radar or TCAS. Without a direct statement from the pilot, GEIPAN had no description of the UAP's characteristics and could only analyze the radio exchanges to try to reconstruct the witnesses' and UAP's positions and paths. The analysis found that: - Atmospheric conditions that day were unfavorable for another aircraft's wake turbulence to persist. - The weather data suggested that the turbulence and UAP passage were not necessarily related; their perceived connection was probably one source of the pilot's sense of strangeness. - The visually observed UAP probably corresponded to the TCAS target, because its position appeared to match the cockpit view. - If so, it had a transponder and should also have been identifiable by air traffic control radar. - Without a description, GEIPAN could not determine why the pilot considered its lights unusual. A GEIPAN pilot expert confirmed the analysis (see expert report in the appendix). The missing pilot statement prevented a specific hypothesis. An inconsistency remained in the exchanges between EZY926L and the controller: TCAS detection strongly suggested an aircraft with a transponder, yet air traffic control had no radar detection. Without the pilot's testimony, both the case's strangeness and evidential strength were rather low. GEIPAN classified it C for insufficient usable information.