San Diego ? Crews will search the Pacific’s chilly waters overnight for nine people lost two days ago when a Marine Corps helicopter and a U.S. Coast Guard plane crashed in midair, though hope of finding survivors fades with each hour, a top Coast Guard commander said Saturday.

Rear Adm. Joseph Castillo said at a late afternoon news conference that there was still a chance of survivors among the seven military personnel aboard the Coast Guard C-130 and the two in the Marine Corps AH-1W Super Cobra helicopter. Though water temperatures are in the low 60s, all had access to heat-retaining drysuits and were in excellent physical shape.

A Pentagon official said a day earlier that the crash likely killed all aboard. But Castillo said the search was ongoing. “We don’t ever want to suspend the case prematurely, when there may be someone out there. … But hope gets less every day. My hope today is not what it was yesterday.”

The two aircraft collided at 7:10 p.m. Thursday as the Coast Guard was conducting a search operation for a missing boater. The Marine helicopter was flying in formation with another Cobra escort helicopter and two large troop transports en route to San Clemente Island, 50 miles off the coast, for a nighttime training exercise.

Families of the missing said they were grateful rescuers weren’t giving up.

Jennifer Wiegandt Seidman she said holds out hope that her husband, Chief Petty Officer John Seidman, has managed to survive. Seidman is a flight engineer with a 23-year career in the Coast Guard.

“I don’t want to let my mind go to thinking the worst,” she said from the couple’s home in Carmichael, Calif. “John knows what he’s doing, and he’s fit and he’s very smart. They’re saying that they’re still looking.”

The Seidmans married in 2001 and Seidman, 43, is stepfather to her three children, aged 10, 12 and 13, she said.

A search was also continuing Saturday for the missing boater, David Jines, Castillo said. Jines, 50, was reported missing by a friend and was last seen in a 12-foot motorized skiff.

Six Coast Guard cutters and three helicopters hunted for any survivors of the midair collision. Crews scanning a 644-square-mile patch of ocean in waters about 2,000 feet deep found debris from both aircraft, but there was no sign of the crew members or their bodies.