Navy officials said the MH-60S Seahawk was conducting routine flight operations from the USS Abraham Lincoln last Tuesday when it crashed down into the sea roughly 60 miles of the San Diego coast.
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The helicopter reportedly touched down on the flight deck and "experienced side-to-side vibrations." It caused the main rotor to strike the deck and the helicopter fell over the side of the aircraft carrier.
The crash summary in a Naval Safety Center document, first reported by the Navy Times, did not include any information on what might have caused the vibrations.
Michael Canders, a retired military helicopter pilot who is the director of the Aviation Center at Farmingdale State College in New York, told the Navy Times that side-to-side vibrations can occur if rotor blades are out of balance.
Several sailors were injured, and five others were declared missing.
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After several days of searching for the missing crew, they were presumed dead on Saturday.
The Navy identified all five service members on Sunday, including Lt. Bradley A. Foster, a pilot from Oakhurst.
The Associated Press contributed to this report.