RENO, Nev. - Ten U.S. Navy crew members narrowly averted disaster when their helicopters accidentally dipped into Lake Tahoe in September while they tried to take photos for the squadron's Facebook page, military investigators concluded.

A Navy report found that crew members' unplanned hovering without sufficient power caused the MH-60R Seahawks to drop without warning to the water of Emerald Bay. Both aircraft were able to regain altitude and land nearby.

There were no injuries, but damage to the helicopters totaled $505,751 in the incident captured in a video filmed by a group of hikers and posted on YouTube.

The report, released yesterday, recommended no punitive action, but a Field Naval Aviator Evaluation Board permanently stripped two Navy instructor pilots from San Diego of their flying status and ordered two student pilots to undergo at least six months of repeat training because of the Sept. 13 incident, the San Diego Union-Tribune reported.

Another flight instructor was placed on a year of probation and can't fly during that time.

Their names were not released because their punishments were considered a private administrative matter, said Lt. Aaron Kakiel, of Naval Air Forces at North Island Naval Air Station.

"The mishap was entirely preventable," Vice Adm. Allen Myers, commander of all naval air forces, said in the report. "The aviation community was lucky this day, and a horrific loss of life was narrowly avoided."

Among contributing factors, investigators said complacency, a lack of flight discipline and a succession of poor judgments nearly led to the loss of the two, $33 million helicopters and 10 sailors.

Crew members from HSM-41 at North Island Naval Air Station in San Diego were returning from an air show in Sacramento, Calif., when they tried to maneuver their helicopters about 70 feet above the lake to take the Facebook photos.

The report said their practice of taking Facebook photos on the flight was a distraction and a contributing factor to the mishap

Retired Navy jet pilot Steve Diamond told the Union-Tribune the punishment was just but still "a crushing blow" for an aviator.

"It sends a message to a whole generation of aviators: Hey, you can't do this. So it has a higher purpose," he said. "Aviation is unrelenting when it comes to risk and safety."