Three people suffered fatal injuries when the helicopter plunged into the East River shortly after takeoff.
The victims included a British woman, living in Australia, who was in New York to celebrate her 40th birthday. Her mother and domestic partner also died.
The pilot was a family friend who survived.
The National Transportation Safety Board said in a report Friday that the helicopter was at least 12 kilograms overweight when it took off.
Investigators say the weight, wind factors and an ineffective pilot manoeuvre caused the aircraft to go into a spin.
New York: US safety authorities say a fatal crash at a New York City heliport in 2011 was likely due to overloading and the pilot's failure to recover from an unexpected flight motion.
First Published: Friday, March 01, 2013, 23:21