Intended as a large trans-ocean ‘flagship’ for Air France, Latécoère designed in 1938 the Laté 631. It was for that time a huge ship fitted with six engines. It was intended for trans-Atlantic mail delivery and for luxury transport of (rich!) passengers. Work commenced shortly before the outbreak of the war and after the armistice with Germany the Latécoère works were allowed to finish the construction under the Vichy government. First flight took place on 4 November 1942, but the trials in France were halted when Germany confiscated it. The Laté 631 prototype, carrying the civil registration F-BAHG, was flown to Friedrichshafen in Germany. It was the intention to use it as a long-range patrol flying boat fitted with military equipment, but on 17 April 1944 it was destroyed at its moorings on Lake Constance during an Allied Mosquito raid and in total it only logged 40 flying hours.
The second 631 was meanwhile completed in 1943 in the Toulouse plant. To prevent it from being destroyed in an air-raid it was dismantled and hidden. After the liberation of France the construction was completed and it made its first flight on 6 March 1945 at Biscarosse. Carrying the registration F-BANT and named ‘Lionel de Marmier’ it went to Air France for use in the African French colonies. After the war another nine were ordered and built for use by Air France carrying the civil registrations F-BANU, F-BDRA, F-BDRB, F-BDRC, F-BDRD, F-BDRE, F-WDRF and F-WDRG. The ninth and last machine would have been registered F-WRDH but it was never flown. The Laté 631 did not have a very lucky career. F-BANU crashed on 28 March 1950 killing all ten occupants on board. Another fatal crash took place with F-BRDC on 1 August 1948 with the loss of 12 crewmen and 40 passengers. Also F-BDRD crashed on 21 February 1948 with the loss of the crew of seven and 12 passengers. With the loss of the fourth machine, F- BRDE on 10 September 1955 all other Laté 631’s were grounded and stored at Biscarosse inside a hangar. They were all severely damaged when the hangar collapsed during a storm and finally they were all scrapped. The Laté 631 was the last airplane built by the Latécoère company.