Philippe and his friend, Sandrine, were returning from the private clinic of Mousseaux in Evry, Essone, where they had gone to visit Josianne, Philippe's wife, who had just that day delivered fraternal twin boys, Aurelien and Adrien.
Sandrine who drove the car, Philippe being a passenger seated on her right. They drove toward Mennecy, where they both live, and were travelling on D-153, parallel to the A6 motorway.
Arriving at the hill village of Lisses about 7:00 p.m. - 7:15 p.m., they saw a strange object coming from their right. It was Philippe who was able to observe this mysterious object quite well, thanks to his position in the car. Philippe said that it seemed to be piloted or under good control.
The object came from the right, moving at a slow speed, comparable to that of a bicycle, and it moved consistently, without accelerations or stops. It did not emit any noise or heat, but rather a light smoke, like steam or water vapor, which came from some white lights.
The UFO appeared to be a huge, compact, rectangular mass, with a surface shiny, like aluminum.
The length was estimated at about 655' and the height about 330' In this mass there were many white lights, with some of them projecting large white beams. Within this rectangle, the lights seemed to be connected by a structure. The whole object stood out from the night sky, being therefore clearly visible.
The UFO was seen through the front windshield by Philippe, seated as a passenger on the right side of the car. Then the car was stopped and the machine was observed through the lowered side window.
The distance of the witnesses to the UFO was difficult to estimate, perhaps between 1600' and 2500'.