A fatal helicopter crash near a Manhattan heliport in 2011 was likely due to overloading and the pilot's failure to recover from an unexpected flight motion, federal safety authorities said in a report released Friday.
Three people suffered fatal injuries when the helicopter plunged into the East River moments after taking off from a helipad.
Also killed were Marra's mother, Harriet Nicholson, who was also British but lived in Portugal, and domestic partner, Helen Tamaki, who was a citizen of New Zealand but lived in Sydney.
The pilot was a family friend who managed an airport in Linden, N.J. He survived.
The National Transportation Safety Board said in its final report on the crash that the helicopter was between 28 pounds and 261 pounds overweight when it took off.
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.