Italy ? Two missing American balloonists were plunging toward the Adriatic Sea at 50 mph when they dropped off air traffic control radar, a sign that they crashed and almost certainly were killed, organizers of the race they were competing in said Friday.

Flight director Don Cameron said that high rate of descent, if confirmed, leads him to be “very pessimistic” about the fate of veteran pilots Richard Abruzzo and Carol Rymer Davis.

The “only shred of hope” is that the readings from air traffic control in Zagreb, Croatia, were from the outer limits of its radar zone and might be incorrect, Cameron said.

Abruzzo, 47, of Albuquerque, New Mexico, and Davis, 65, of Denver, Colorado, were participating in the 54th Gordon Bennett Gas Balloon Race when contact was lost Wednesday morning in rough weather over the Adriatic.