The U.S. Navy marked the opening of Fleet Week 2009 on Wednesday with a flyover by six military aircraft, and the city warned residents about the spectacle in advance to prevent a repeat of the panic that occurred when jetliner zoomed past lower Manhattan three weeks ago.

Three F/A-18 Hornet fighters and two of the Marine Corps' V-22 Ospreys raced up the Hudson River at 1,000 feet as 13 U.S. and Canadian warship paraded past Manhattan's towers to begin the six-day event. A police spokesman said he was "unaware" of any public alarm.

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The city's Office of Emergency Management had issued a public reminder that the fly-by would occur, a notice not provided on April 27 when the Pentagon staged a low-level "photo op" flight by a presidential Boeing 747 past the Statue of Liberty and the site of the former World Trade Center that was destroyed by hijacked jetliners on Sept. 11, 2001.

That incident sent panicked workers rushing into the streets in fear of another attack. The Pentagon later apologized and the head of President Barack Obama's White House military office resigned.

The F/A-18 Hornets flew in tight formation, followed by the two tilt-rotor Ospreys, making their New York debut.

This year's Fleet Week is the smallest ever, with only three major U.S. warships and five Canadian vessels in the lineup. The largest is the USS Iwo Jima, a 40,500-ton assault helicopter carrier.