On 1–2 September 1930, Costes with Maurice Bellonte, flew the ""Point d'Interrogation"" from Paris to New York, as the first heavier-than-air aircraft to reach New York in the more difficult westbound direction between the North American and European mainlands. They covered either 5,850 km (3,633 miles) or 6,200 km (3,850 miles), according to different sources, in 37 hours 18 minutes. While flying over Portsmouth, New Hampshire, they lost their navigational map out of an open window of the plane. Two children saw the map falling from the sky while they were watching for the flight to cross over their farm. The children, Louise Stef and her brother John, returned the map to Costes, who had asked for its return through the media.