The La Ferté-sous-Jouarre gendarme triangle over the A4 at Ussy-sur-Marne

In January 1994, the crew of Air France flight AF3532 reported an unidentified object over Coulommiers, in Seine-et-Marne. Five months later, the same département produced another file that would end up unexplained.

Friday, 24 June 1994. Three gendarmes from the La Ferté-sous-Jouarre brigade were on night traffic patrol in a Renault Trafic van, windows open. The official report blanks out their names. Le Pays Briard gives only initials: C…, the driver, R… and EC…

About 2:40 in the morning, near Ussy-sur-Marne, lights above the A4 motorway caught their attention. "The further we drove towards it, the clearer it became," they reported. It was a triangular object, stationary at a height they could not determine. Three yellow-white glowing points formed the triangle. In the middle was a pyramid-shaped centre, its tip pointing at the ground.

They stopped the van. The object came to them. "It moved slowly towards us, keeping the same altitude, then stopped above our unit." It hung directly overhead. No sound. No smoke. No smell.

Then they put the van into first gear. The object headed west. "It left at a dizzying speed; within one second only a faint point remained." The encounter lasted about ten minutes. Somewhere along the way, the van's radio equipment stopped working.

The gendarmes wrote an official report, with a sketch of what they had seen, and sent it on. Today it sits in the public archive of GEIPAN, the unidentified phenomena unit at CNES, the French space agency. GEIPAN classified it D: a strange to very strange phenomenon, with testimony of medium to strong consistency. Only about 3.5% of its cases carry that class. The verdict is short. "No explanation could be provided for the phenomenon." Press accounts say the radio failure weighed in that decision.

The report says neither size nor altitude could be determined. Météo France records for the night show a few clouds, no rain and a light wind.

No one has accused the gendarmes of a hoax, and GEIPAN proposes no mundane cause. None of the published accounts says whether air traffic or helicopter activity that night was checked. GEIPAN has noted in another triangle case that UFO stereotypes can shape witness descriptions. It has not applied that observation to the Ussy-sur-Marne case.

In 2015, journalist Jean-Michel Rochet told the story in "La Brie de l'étrange", a series for Le Pays Briard. France 3 Paris Île-de-France later listed it among nine unexplained cases in the region's GEIPAN files, and the podcast Les Dossiers OVNI paired it with the Conches-en-Ouche triangle. The Belgian triangle wave of 1989 and 1990 forms its backdrop. Three trained observers. One silent triangle. A file that still ends without an answer.