Transcript for Images show smiling passengers moments before fatal helicopter crash
Now, to new reporting this evening after that awful helicopter crash here in new York City. The final images of the five passengers killed, recording their flight just minutes before the tour helicopter went down in the east river. Tonight, the pilot, the only survivor, now saying one of the passenger's bag straps or a safety harness tether got caught on the fuel. ABC's David Kerley is on the scene for us. Reporter: Tonight, new images inside that helicopter flight. Smiles all around during takeoff. Just minutes later, tragedy. Zero-lima-hotel, mayday, mayday, mayday. Zero-lima-hotel, what's the matter? You okay? Engine failure. Reporter: The sunset photo and sightseeing tour going down in the eas Marine 6 does have one diver in the water. Reporter: The five passengers unable to escape the sinking chopper in icy water. It almost looked very surreal. And next thing we know, it's approaching the water, slowly. And then it just completely crashed and then sunk. Reporter: The lone survivor, the pilot, telling authorities that a tether or part of a passenger's harness snagged one of the fuel levers, shutting it. Bleeding the engine of fuel. Tethers are used to allow photographers, or in this case, a coast guardsman, to move around a chopper in flight. But the ill-fated flight may have suffered another disaster. It was equipped with floats used for emergency water landings. But as the New York chopper nears the water, the pilot says the right float fails to inflate properly. The helicopter slams to that side. If those floats had worked properly, we would have had five people probably still alive. Reporter: The five passengers in their late 20s and early 30s. Among them, a journalist, a firefighter, an Argentinian tourist and two tour company employees. None of them able to free themselves from the harness system under water. Passengers on a similar flight complained about those harnesses. Somebody who flew in a sister helicopter last night said it was not easy to get out, when they're on the ground, to get out of their harnesses. We will be looking at this helicopter to see whether the harnesses were functioning. Reporter: Liberty helicopters, according to federal authorities, has two incidents, including a 2009 crash with a small plane that killed nine. David Kerley with us live tonight along the east river here in New York City. And David, you mentioned those harnesses a moment ago. They were difficult to get out of. That the police divers had to cut all the victims free? Reporter: These are multi-point harnesses come over your shoulders and other parts of your body, that passengers may not have been familiar with the release, of course, the pilot wore it every day, he was able to get out of the craft. David? David Kerley with us tonight. David, thank you.
This transcript has been automatically generated and may not be 100% accurate.