The helicopter was undergoing sea trials, taking off and landing on the frigate Yaroslav Mudry, when the accident happened, Russian Baltic Fleet commander Vice Adm. Viktor Mardusin told RIA Novosti.
"The cause of the crash is currently being established," he said.
A Baltic Fleet spokesman in Kaliningrad said the helicopter's two pilots and three other crew members all survived, telling the news service the helicopter's blades grazed the frigate before it crashed.
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