The pilot of a helicopter who died when he crash-landed on top of a skyscraper in Manhattan, New York, this month "did not know where he was", a preliminary report has said.
The National Transportation Safety Board (NTSB) said he asked to return to a heliport shortly after taking off amid bad weather.
Tim McCormack, 58, was the only person on board when he crashed on 10 June.
His helicopter burst into flames on hitting the 54-floor building.
At the time, New York state Governor Andrew Cuomo said the incident brought back painful memories to New Yorkers, who "have a level of PTSD from 9/11".
"So as soon as you hear an aircraft hit a building, I think my mind goes where every New Yorker's mind goes," he said.
How did the crash happen?
An initial report by the NTSB said the pilot had originally departed from Bel-Aire Farms Heliport in New York state, with another pilot-rated passenger at about 10:30 local time (15:30 GMT).
He then briefly refuelled in Poughkeepsie, before flying to East 34th Street heliport in the city, where his passenger departed.
The report says McCormack waited there in a lounge for about two hours, amid rainy and foggy weather conditions.
He then reportedly told staff he saw a "20-minute window to make it out" towards his final destination of Linden, New Jersey, and he departed at about 13:30 local time.
The report says about five to seven minutes after take-off, he then "contacted Atlantic Aviation and made a request to return to the heliport".
After being advised to land, he then radioed to say he "did not know where he was".
The NTSB said he flew erratically over the city's East River, changing course and altitude several times before making a dramatic turn and straying over Manhattan.
He eventually struck the 54-storey AXA Equitable building at 787 Seventh Avenue - close to Times Square.
Eyewitnesses at the scene described the building shaking with impact. There were no other casualties.
The NTSB said all major components of the twin-engine Agusta A109E helicopter were found at the accident site, but "small pieces of debris were recovered from the 50th floor and street level".
The helicopter, which was used for executive travel, had been inspected the month before, according to the report.
Who was the pilot?
Federal Aviation Administration (FAA) records show McCormack, who was a volunteer firefighter, had been certified in 2004 to fly helicopters and single-engine airplanes.
At the time of his death, he was qualified to fly commercially and as an instructor and had accrued more than 2,800 flight hours.
In the aftermath of the crash, McCormack's family described him as a "caring and compassionate man who put others first over himself".
Their statement said they believed he had landed on the roof "so that it didn't impact anyone else's life except his own".Skip Twitter post by @CNNNewsource Report End of Twitter post by @CNNNewsource
The helicopter was registered to American Continental Properties, which McCormack had worked with for five years.
In the aftermath of the accident, Mayor Bill de Blasio suggested the FAA should tighten regulations for aircraft flying close to Manhattan.