Chile.Antofagasta · the glowing cloud two airline crews saw over northern Chile

At 00:30:48 UTC on 7 September 2023, 21:30 on the 6th in Chilean summer time, the captain of Sky Airline flight SKU329, which had taken off from Iquique for Santiago, called the Iquique Area Control Centre. He was flying at 35,000 feet, some 85 kilometres north of Antofagasta airport. The recording, which SEFAA transcribed, reads: 'We have… a light up there, we thought it was the Moon, it looks like a flash… we can't really tell the altitude… We thought it was the Moon, covered by clouds, but it's moving vertically'. Asked whether it was above his position, he said no, to the southwest. The controller told him she had no traffic, that the nearest was on the same airway 113 miles away. Almost two minutes later he confirmed he still saw it: 'it's fading, but in the centre I'd say you can see every so often a light that shines like a beacon or a strobe light, but at very high speed, very fast. Very high too'. At 00:32:58 JetSMART flight JAT026 broke in: 'we see the same… Right now it's above us', and confirmed it was overhead. At 00:33:16 SKU329 said it had now disappeared, that it had been 'three or four flashes'. The controller reported that the two aircraft were 321 miles apart, and JAT026, four miles from the PUNAP waypoint, repeated that the light had passed over them 'and had a kind of beacon'.

The Iquique air traffic operations officer sent SEFAA, the anomalous aerial phenomena section of the Directorate General of Civil Aviation, the controller's handwritten report and the synchronised radar and audio video. The office placed both aircraft with the tracking system; its map puts JAT026 off the coast, north of La Serena. In the radar image it highlighted the possible presence of at least three military aircraft in the line of sight of the SKU329 crew; Iquique's flight plans did not record them, but the Air Force liaison officer confirmed night operations by institutional aircraft in the area. With that, on 10 October 2023 it closed the case as 'Resolved': what was reported arose from 'the sporadic sighting of institutional air operations'. It had not obtained the crews' identities, requested by email three times in September.

On 11 February 2024 the SKU329 captain himself filed a report with his account and five images. He wrote that, already at cruise, he saw to the southwest, out over the Pacific, something that looked like a cloud glowing as when the Moon is behind a cloud, although, he wrote, that night 'we never could see the moon'; that his first officer first thought it was the Moon and then that it was not; that the cloud grew vertically, expanded in all directions and formed a halo that came to stretch 'from Argentina to the Pacific', with a flash at its centre, sometimes white and sometimes red, and at the end three white lights almost in a triangle, all within about 30 minutes. SEFAA examined four of the images with error level and copy-move analysis: they had not been altered, came from a Samsung S22 Ultra and were taken between 21:28 and 21:30 local time on 6 September. They showed a luminous object of gaseous appearance through which a star could be seen. The office searched the United Nations launch register, found that of the Chinese military satellite Yaogan 33-03 (2023-136A) on that 6 September, on a Long March 4C from Jiuquan into a sun-synchronous orbit, and on 14 February 2024 it reissued the report and concluded that what was reported was the launch of that rocket.

The case brings together witnesses and documentation: two crews from two airlines, 321 miles apart, spoke live with Iquique control about the same thing, and the recording preserves it timed to the second; and four phone photos, examined and found unaltered, capture it in those same minutes. Report 1967 says the photos are from 6 September, 'one day before what was reported', but by our reckoning there is no such gap: 21:28 in Chile on summer time was 00:28 UTC on the 7th, two minutes before SKU329's call. The gap lies in the captain's account, which dated the sighting the 7th in local time. That an object should be seen to the southwest from one aircraft and directly above another almost 600 kilometres away only fits something very high or very large, which is what the photos show and what the second conclusion holds; that is our deduction. The Moon, which SKU329 mentioned (and, according to the captain, the other traffic too), was below the horizon, some 63° below it by our calculation.

The case also shows how an official explanation can change. The first, in October 2023, rested on echoes of possible military aircraft on radar and on confirmation of night Air Force flights; the second keeps that paragraph but concludes something else, without explaining why it drops the first. What changed it were the photos and the description of a cloud that grew and let stars show through, the look a rocket's propellant plume usually has when lit by the Sun at great altitude. By our calculation, at that hour the Sun was about 28° below the horizon to the west, so something hundreds of kilometres up in that direction could be lit, as the captain described.

The identification has a problem the report does not see. It speaks of the 'launch', but according to Jonathan McDowell's satellite catalogue the satellite separated at around 18:26 UTC on 6 September, by the catalogue's estimate, some six hours before the photos; what was seen over Chile would not be the rocket's ascent but its third stage already in orbit, which the catalogue places in an orbit of 496 to 683 kilometres. By our calculation, that stage could not have been in view. Using the February 2024 orbital elements published in the report itself, taken back in time with the precession of a sun-synchronous orbit, the plane of the satellite and the stage passes over Jiuquan at about 18:15 UTC on the 6th, which confirms the calculation; at 00:30 UTC on the 7th, that plane lay some 48° of arc from JAT026 and some 53° from SKU329, whereas something 500 or 680 kilometres up is only visible within about 25 to 29°. The figure with which SEFAA estimates the trajectory draws it over the Pacific, far to the southwest and running west-southwest to east-southeast, hardly compatible with an orbit inclined at 98°, and the text concedes it may have followed 'a parallel course further north' without checking.

McDowell's catalogue offers another launch that matches the time; this is our deduction, not SEFAA's, and not an identification. At 23:42 UTC on 6 September, a Japanese H-IIA lifted off from Tanegashima with the XRISM observatory and the SLIM lunar probe, into an orbit inclined at 31°. According to the Japanese space agency, SLIM separated about 47 minutes and 33 seconds after lift-off, and the catalogue dates that separation at 00:29:50 UTC on the 7th: between the photos, from 00:28:55 to 00:30:02, and SKU329's first call, at 00:30:48. By an approximate calculation, the second stage's track was crossing the southeast Pacific towards Chile in those minutes and was above the horizon of both aircraft. Without the stage's precise position or the exact direction of the photos, this is a coincidence of time and of approximate geometry; but, unlike the Chinese rocket, this one could have been in view.

Nor does the report say who took the photos, although the captain supplied them; he attached a fifth image, which he attributed to a JetSMART aircraft flying along airway UQ814 towards Calama, and which the office did not analyse; he also mentioned photos taken from the ground at Tongoy that the report does not examine.

There are also inconsistencies of detail. The flight appears as SKU329, SKU239 and SKU234; the waypoint as PUNAP and PUNAB. The handwritten report says fewer than 10 seconds passed between the two aircraft's reports, but in the transcript about 20 seconds separate SKU329's second description from JAT026's, and two minutes from its first call. The captain recalled the controller telling him the only traffic was 300 miles to the south and belonged to LATAM; the recording says 113 miles, and the aircraft that answered was JetSMART's. His account also says the other traffic saw the cloud 'to the west of its position', whereas JAT026 said it was passing 'over us'; and the summary of his report says the sighting 'lasted more than a minute', whereas the account speaks of about 30 minutes. It is the same night corridor of northern Chile as ↗ and ↗.