A pilot who survived when his helicopter went down in Manhattan's East River, killing five passengers, reported engine failure in an emergency radio transmission, it has emerged.
The pilot is heard saying "Mayday, mayday, mayday" during the crash on Sunday night.
He reported "an engine failure over the East River" and referenced a hotel, while the person at the other end of the transmission had trouble making out what the pilot was saying.
The pilot freed himself and was rescued by a tugboat, but emergency divers had to remove the passengers inside the charter helicopter which was being used for a photo shoot from tight safety harnesses while they were upside down, Fire Commissioner Daniel Nigro said.
He said: "It took a while for the divers to get these people out. They worked very quickly as fast as they could. It was a great tragedy that we had here."
The National Transportation Safety Board dispatched investigators on Monday.
Video taken by a bystander and posted on Twitter shows the red helicopter land hard in the water and then capsize, its rotors slapping at the water.
Witnesses on a nearby waterfront esplanade said the helicopter was flying noisily, then suddenly dropped and quickly submerged. But the pilot appeared on the surface, holding onto a flotation device as a tugboat and then police boats approached.
A Federal Aviation Administration spokeswoman said the Eurocopter AS350 was owned by Liberty Helicopters, a company that offers both private charters and sightseeing tours popular with tourists.
The skies over New York constantly buzz with helicopters carrying tourists, business people, traffic reporters, medical teams and others. Crashes are not unheard of.
In 2009, a sightseeing helicopter of the same model and operated by the same company as the one involved in Sunday's crash collided with a small, private plane over the Hudson River, killing nine people, including a group of Italian tourists.
A crash in October 2011 in the East River killed a British woman visiting the city for her 40th birthday. Two other passengers died weeks later as a result of their injuries.
A helicopter on a sightseeing tour of Manhattan crashed into the Hudson River in July 2007, shaking up the eight people aboard but injuring no-one. In June 2005, two helicopters crashed into the East River in the same week.
One injured eight people including some banking executives. The other hit the water shortly after take-off on a sightseeing flight, injuring six tourists and the pilot.