WASHINGTON: The collision that sent a sightseeing helicopter full of tourists and a small plane into the Hudson River on Saturday comes less than a month after a federal watchdog warned that safety oversight of such charter flights is too lax.

A small plane collided with a New York City sightseeing helicopter carrying five Italian tourists on Saturday around noon. The accident scattered debris in the water and forced people on the New Jersey waterfront to run for cover. Authorities believe all nine people aboard the two aircraft were killed.

National Transportation Safety Board Chairman Debbie Hersman told a news conference that a helicopter pilot on the ground at the heliport for Liberty Tours, which operated the doomed sightseeing craft, saw the plane approaching the helicopter and tried to alert the helicopter pilot by radio.