Chile.Petorca · the flashes LXP337 saw crossing towards Argentina

On 23 February 2018, on the instructions of the head of the Santiago Area Control Centre, an air traffic controller reported as an 'occurrence' something that had affected LATAM flight LXP337 eleven days earlier, on 12 February. The report by SEFAA, the section of Chile's Directorate General of Civil Aviation that studies anomalous aerial phenomena, says it happened 'at dawn', but gives the time: 0:53 local time, 3:53 UTC, that is, in the middle of the night. The aircraft, an Airbus A320 registered CC-BAZ flying the Antofagasta–Santiago route, was near the DABIT reporting point over Petorca province, and its captain reported a flashing light moving from west to east, at a high altitude relative to his aircraft. He asked whether there was traffic nearby and was told there were no returns on radar.

SEFAA merged the audio files into one and transcribed the exchange. The pilot asks whether there is 'high-altitude traffic entering Argentine airspace coming from the Pacific', from west to east. 'No sir. No traffic from sea to cordillera.' 'I can see some flashes up there. Never mind.' Shortly afterwards, control calls him back to confirm that the query was his and whether he still has the flashes in sight. The pilot says yes, that what he saw 'was following the route more or less… so to speak… like the Magellanic Cloud. That was the route you could see.' He no longer sees it, 'but you could see a flash like… stoplights'. The report places the exchange with the Santiago area control centre, though its summary says the report was made to the tower.

The investigation identified the captain and wrote to him asking for details, with the CEFAA form for civilian pilots; by the date of the report five messages had been sent without reply. So that he could draw on it the path of what he saw, the office prepared a sky chart of the moment centred on DABIT, which it places at 32° 15′ 05″ S, 70° 50′ 06″ W (the chart's own label says 32.0902° S and gives the time as 0:50, UTC −3). It checked with the La Serena and Santiago weather reports that visibility conditions were good along the route and reconstructed the descent: the aircraft passed SIMOK at 30,525 feet and DABIT at 20,300, on a track of 178° at about 362 knots, bound for Santiago. The Air Force delegate on the committee said on 15 May 2018 that it was not a FACh flight. Another adviser, on 30 January 2019, leaned towards an atmospheric phenomenon above the troposphere, gases ionised by the electric fields there that show up as lights, and pointed to the possible reentry of rotating space junk capable of glinting; he added that, given its altitude and because radar did not detect it, it posed no immediate risk and it seemed reasonable to file the case. The conclusion, of the same day, says the phenomenon did not threaten flight safety and that the available information allows its origin to be narrowed to 'high-altitude aerospace traffic and, possibly, the manifestation of atmospheric luminescence'. The header classifies it as 'Resolved'.

The case is valuable for the live testimony, not for the solution. The recording preserves the captain's words at the time, with a direction (west to east, from the Pacific towards Argentina), a relative position (above the aircraft) and a celestial reference, the Magellanic Cloud, that would make it possible to fix its path across the sky. But the pilot answered none of the five messages and did not draw the route on the chart prepared for him, and there was no image or radar return. With that, SEFAA did not identify an object: it narrowed the origin to two families of explanations, one space-related and one atmospheric, and filed the case because it did not affect flight safety. The 'Resolved' classification in the header says more than the conclusion does.

Some checks of our own narrow those two options; they are deductions made for this record, not statements of the report. At 3:53 UTC, from DABIT, the Sun was about 41° below the horizon, so low-orbit satellites, the great majority, were in the Earth's shadow and could not reflect its light: overhead, only what lay more than about 2,100 kilometres up was still lit, and towards the Large Magellanic Cloud, which stood at the same azimuth as the Sun, the threshold fell to about 1,200 kilometres. Rocket stages or satellites in high orbits that flash as they tumble remain possible. Jonathan McDowell's satellite catalogue records no reentry on 12 February 2018; the nearest with a recorded time, that of the Iridium SV043 satellite, is listed on 11 February at around 14:20 UTC (with the time flagged as uncertain), some thirteen hours earlier, and the same catalogue gives another on 13 February, that of Iridium SV049, and Kosmos 2251 debris on the 11th and the 13th with no time. Absence from the catalogue does not exclude a reentry, because uncatalogued debris is not listed. The Moon was below the horizon. The Large Magellanic Cloud stood to the south-southwest, about 44° high, that is, ahead of and slightly to the right of an aircraft on a 178° track: the pilot's reference points to that part of the sky. None of this rules out a space object or a luminous phenomenon of the upper atmosphere, but it does not confirm them either.

What the file does exclude is known traffic: Santiago control had none 'from sea to cordillera', radar showed nothing and the Air Force said it was not one of its flights. The witness was an airline pilot on descent, in good visibility, who merely asked and described without offering an interpretation, and the report was filed eleven days later at the initiative of air traffic control. It is an example of the short crew reports SEFAA receives from the corridor between northern Chile and Santiago, where the lack of images leaves the case with a generic explanation.