Federal officials have released new details regarding last year's deadly helicopter crash in the East River, detailing how multiple passengers struggled to free themselves from safety harnesses as the aircraft quickly filled with water.

On Monday, the National Transportation Safety Board published a transcript of video captured by a GoPro mounted aboard the sight-seeing helicopter. "How do I cut this?" one passenger asks, as the helicopter becomes submerged.

Seconds later, a different passenger "looked downward toward his chest and used both hands and manipulated the shoulder strap portions of his supplemental restraint," according to notes provided by the federal agency. A third person was seen reaching for a hook knife previously visible on the camera, but could not access the tool in time.

All five passengers aboard the chartered helicopter were killed in the crash, while the pilot, Richard Vance, survived. Vance told investigators that he tried to save one of the passengers, before bailing out of the sinking helicopter.

The aircraft was operated by Liberty Helicopters, which offers "doors-off" sightseeing trips to tourists, and was manufactured by Airbus. After one of the victims sued the chopper-maker last year, an attorney for Airbus argued that the victims should have known what they were getting into.

“Trevor Norris Cadigan voluntarily undertook and assumed the known risk of being a passenger in a ‘doors off’ flight while knowingly being restrained by a harness from which he could not easily release himself,” wrote lawyer Thomas Mealiff in court papers.

The new transcript also shows the pilot laughing with the passengers minutes before the unexpected descent. "They tell us we're not supposed to drink before we fly too—but I mean come on," the pilot said at one point. (This was "spoken in a joking matter," according to the agency's notes).

Later, Vance instructs the passengers: "leave your seatbelts on the whole flight. You're tethered in. You're not goin' anywhere."

The transcript was made available ahead of a December NTSB meeting to determine the cause of the fatal crash.