NEW YORK (CBSNewYork/AP) -- A fatal crash at a Manhattan heliport in 2011 was likely due to overloading and the pilot's failure to recover from an unexpected flight motion, according to a report released Friday by the National Transportation Safety Board.
Three people suffered fatal injuries when the helicopter plunged into the East River shortly after takeoff the 34th Street helipad on Oct. 4, 2011.
Five people were on board. Sonia Marra, 40, died as a result of the crash. Her body was found in the wreckage of the helicopter underwater. First responders who plumbed the depths to recover her body said she was not strapped in by a seat belt.
Marra's stepfather, Paul Nicholson, 71, her mother Harriet Nicholson, 60, and her partner, Helen Tamaki, 43, were all pulled from the water and taken to Bellevue Hospital.
Tamaki died a week after the crash; Harriet died a month later.
PHOTO GALLERY: East River Helicopter Crash
Paul Dudley, the pilot and family friend, managed to swim to safety. Dudley owns Linden Airport Services, which manages the Linden Municipal Airport.
The group was taking a sightseeing tour to celebrate Marra's and her stepfather's birthdays. Paul Nicholson and Dudley were the only survivors.
Dudley is an experienced pilot and has even been in an emergency situation before. In 2006, he landed a Cessna aircraft in a Brooklyn park near Coney Island after the engine failed. No one was hurt in that emergency landing.
The NTSB said in its final report on the crash that the helicopter was between 28 pounds and 261 pounds overweight when it took off.
"The pilot had initially anticipated taking two passengers on the flight, but the two passengers brought two additional adults with them who also boarded the helicopter," the report stated.
The NTSB said Paul Nicholson told investigators Dudley did not ask for anyone's weight or perform any calculations before takeoff.
"The passenger weights that the pilot provided investigators following the accident were significantly less than the weights provided by medical personnel and the surviving passenger," the report said.
Investigators say the weight, wind factors, an ineffective pilot maneuver in response to an onboard alarm and a subsequent surprise yaw caused the aircraft to spin out of control.
The NTSB report released Friday finalizes preliminary conclusions described in another report released in December.
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