ROME, Oct. 2 (UPI) -- Rescuers used an underwater robot Saturday in the search for two American balloonists who disappeared during an international gas-balloon race, officials said.
Equipment on the balloon indicated it made a rapid descent during rough weather over the Adriatic Sea near Italy, CNN reported.
The 20-balloon race started near Bristol, England, last weekend. The missing balloon's pilots are New Mexico resident Richard Abruzzo and Carol Rymer-Davis of Colorado.
Race organizers said it is "unlikely" the balloon's quick descent was a survivable incident.
"This is very pessimistic information," said Gordon Bennett of Coupe Aeronautique.
He said race officials lost contact with the balloon shortly after 8 a.m. Wednesday.
The search area was identified by using transponder readings from air traffic controllers using the balloon's altitude and location, the report said.
"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," a statement released by race officials said.
Italian searchers found small pieces of debris in the ocean and forwarded photographs to race officials.
Officials offered three possibilities for the balloon's fall: Lightning struck it and it exploded; the balloon suffered a failure and went down quickly into the ocean; or the balloon dropped slowly, making survivability more likely.
The balloon carried two one-person life rafts and other survival gear, CNN said.
