Those looking in Lake Mead for a 28-year-old airman from Creech Air Force Base changed their tactics Sunday after the man was feared dead.
National Park Service rangers and members of the U.S. Coast Guard launched a weekend search for the unidentified airman, who disappeared after he jumped out of a 21-foot boat to go for a swim, authorities said.
A woman who was left in the boat with her child called 911 at 2:34 p.m., prompting a response by park rangers, a Coast Guard vessel and a Maritime Safety and Security Team, said Lake Mead National Recreation Area Assistant Chief Ranger Randy Lavasseur.
He said rescuers changed strategy from a search-and-rescue mission to a recovery mission, meaning it's unlikely the airman is alive.
"We searched all possible areas where a surviving person could be," Lavasseur said.
He said rescuers began using a side-scan sonar provided by the Nevada Division of Wildlife in hopes of recovering a body by looking in the depths of the lake.
Capt. Katie Roling, a spokeswoman for Creech, said Saturday the missing man is an airman assigned to the 432nd Wing at the base at Indian Springs, 45 miles northwest of Las Vegas.
Roling did not identify him.
Lavasseur said the man, who was not wearing a flotation device, disappeared after he tried to swim as 30 mph winds pushed the boat away from his location.
With the boat adrift, the woman, who did not know how to operate it, called 911, and a Coast Guard vessel responded.
Personnel from the vessel boarded the boat and drove the woman and child to safety.
Lavasseur said divers were not deployed Sunday mostly because rescuers weren't sure where to look.
He said the man went down in a deep part of Boulder Basin.
Rescuers were expected to stop their efforts by about 6 p.m. Sunday night, Lavasseur said.