The Lat‚coŠre 631 flying boat, named “Lionel de Marnier”, operated on a round trip service from Biscarrosse, France to Fort de France, Martinique, with a refueling stop at Port-Etienne, Mauritania. At 15:05 the aircraft took off on the first leg of the return flight. The cruising altitude was 3000 meters in instrument weather conditions. Planned flying time from Fort de France to Port-tienne was 16 hours and 15 minutes. Hourly position reports were made until 00:11 UTC when it reported passing 1927N, 3825W. No contact was established with the flight and the aircraft failed to arrive. A search mission was commenced using a submarine, three ships, a Lockheed Constellation, a Lat‚coŠre 631, three B-17’s and seven B-29’s. On August 6 a U.S. Coast Guard cutter, USCGC Campbell, reported finding two aircraft seats at 18ø17N, 17ø00W. The Campbell and another ship collected several other smaller pieces of debris before the search was called off on August 8. The aircraft crashed into the Atlantic Ocean some 1900 km west off Dakar, Senegal. Conclusions: “The members of the committee are unanimous in attributing the accident to a serious and sudden event whose origin could not be verified with certainty.”