A pilot repeatedly yelled "Mayday" but did not say what the emergency was before his plane crashed into the roof of an Australian shopping centre, killing himself and four American tourists, an accident investigator has said.
Police blamed "catastrophic engine failure" when the twin-engine Beechcraft B200 Super King Air crashed into the Direct Factory Outlet mall in the Melbourne suburb of Essendon on Tuesday, moments after take-off from a nearby runway.
But Australian Transport Safety Bureau chief commissioner Greg Hood said modern twin-engine aircraft were designed to continue flying if an engine failed.
"My understanding is he only used the word Mayday a number of times," Mr Hood said, referring to radio communication from pilot Max Quartermain to air traffic controllers.
"My understanding is he didn't refer to the specific nature of the emergency."
Mr Quartermain, 63, owned charter company Corporate and Leisure Travel.
The passengers were named as Greg De Haven, Russell Munsch, Glenn Garland and John Washburn, who all lived in the Austin, Texas, area.
Mr Quartermain was investigated by the Australian Transport Safety Bureau after a near mid-air collision that happened in September 2015.
Because of that incident, the Civil Aviation Safety Authority, the industry regulatory, required him to undergo proficiency tests to demonstrate he could fly a plane by instruments alone, authority spokesman Peter Gibson said.
Mr Quartermain passed those tests weeks after the near-miss, Mr Gibson said.
Mr Hood said he would not comment on Mr Quartermain or his flying record, adding that his flying record as well as the plane's maintenance record would be part of the crash investigation.
Australian Transport Safety Bureau investigators are to compile a preliminary report within 28 days.
The busy shopping mall had yet to open for the day when the plane crashed after taking off from Melbourne's second-biggest airport at Essendon for a golfing trip to King Island, 255 kilometers (160 miles) to the south.
Mr De Haven's sister Denelle Wicht, of Alexandria, Minnesota, said her brother survived dangerous work in the FBI and while serving in the US Army during Vietnam, only to die while enjoying retirement.
She said the Mr De Haven, 70, was "extremely athletic" and at one time aspired to become a professional golfer, but his young family at the time came first.
After he retired, De Haven went on the senior pro golf circuit.
Mr De Haven and his wife were part of a larger group that included at least two other couples who were touring Australia over the course of three weeks and intended to also see New Zealand, Ms Wicht said.
She earlier told KXAN-TV in Austin that the men had chartered the flight for a round of golf on an offshore island, while their wives stayed behind to pursue other interests.
Mr Munsch was a founding partner in the Texas law firm of Munsch Hardt, which said he litigated some of the most prominent bankruptcy cases in the US, including the 2001 bankruptcy proceedings for Houston-based Enron, one of the largest energy companies in the world, before its collapse.
He would have been 62 on Wednesday.
Mr Washburn was Mr Munsch's neighbour.
Meanwhile, an energy consulting firm in Austin confirmed that Mr Garland, a former CEO and co-founder of the company, also died in the crash.
He was one of the founders of CLEAResult and served as chief executive before retiring in 2015.
White House spokesman Sean Spicer said US president Donald Trump's "thoughts and prayers are with the families of the victims" and that US embassy and consulate officials would provide assistance as the investigation progressed.