The American pilots, Richard Abruzzo and Carol Rymer Davis, disappeared on Wednesday over the Adriatic Sea. Race director Don Cameron told the BBC: "The rate of descent at the last moment was about 50mph (80km/h). If that's correct it's very pessimistic news." The Gordon Bennett Cup race was launched from near Bristol on Saturday. The search, led by the Italian Maritime Rescue Co-ordination Centre (MRCC), continued throughout Friday. The Italian coastguard last had contact with the pair, who won the race in 2004, at 0800 local time (0700 BST) on Wednesday when they reported bad weather conditions. Organisers at the Gordon Bennett control centre said they had examined the transponder readings from the missing balloonists and calculated the change in height of the balloon over the time period recorded. This data indicated the balloon had a moderate descent rate initially which then increased into a high rate of descent, to about 50mph. A spokesman said: "At this rate of descent to the surface, survival would be unlikely. "It is the opinion of the Gordon Bennett 2010 Flight Control Team that the balloon appears to have suffered a sudden and unexpected failure. "The cause of this tragedy is still being examined." The spokesman added that both families had been informed of the latest information.