A 29-year-old man who stole an empty passenger jet from Seattle airport and then crashed it was an airline worker with full credentials, authorities say.
He had worked for Horizon Air for more than three years, towing and tidying aircraft and loading bags.
The man, not yet named, took off late on Friday, forcing the airport to close while two fighter jets gave chase.
After making "incredible manoeuvres", he crashed the plane in Puget Sound and did not survive.
Transcripts of his conversation with air traffic control reveal a man who appears surprised about his feat, who is unclear as to the full operations of the plane, who has no intention to hurt anyone and who ultimately apologises to his loved ones, saying he is "just a broken guy".
What are the latest developments?
Airline and airport officials gave a press briefing on Saturday morning in Seattle.
They declined to give the man's name.
Mike Ehl, director of aviation operations at the airport, said the man "had access legitimately" to the plane and that "no security violations were committed".
Alaska Airlines CEO Brad Tilden said the man had been "background checked".
"He worked his shift yesterday and we believe he was in uniform," he added.
Gary Beck, CEO of Horizon Air, said that "to our knowledge, he didn't have a pilot's licence" and that he had no idea how the man had gained the skills to fly such a "complex machine".
The man was believed to be the only person on board but that has not been confirmed. The FBI is carrying out the investigation.
What happened exactly?
The 76-seat, twin-engine turboprop Bombardier Q400, belonging to Horizon Air, took off from Seattle-Tacoma International Airport at 19:32 local time (02:32 GMT).
Officials say the man used a pushback tractor to first manoeuvre the plane 180 degrees from a maintenance location into the correct position for take-off.
After take-off he performed at least one dramatic roll, pulling the aircraft up just metres from the water before gaining altitude again.
The North American Aerospace Defense Command (Norad) issued a statement saying that two F15 fighter jets were launched from Portland to intercept. A number of videos showed them following the passenger plane, which was flying in an erratic manner.
Norad said the F15s were "working to redirect the aircraft out over the Pacific Ocean when it crashed on the southern tip of Ketron island", about 30 miles (48km) south of the airport.
"Norad fighters did not fire upon the aircraft," it said.
End of Twitter post by @drbmbdgty
Officials say they lost contact with the plane at 20:47 local time, more than an hour after it left the airport.
What did the pilot say to air traffic control?
It varies from options for landing, to apologies for what he is doing to the often bizarre.
The controllers suggest he needs some help flying the plane, to which he replies:
- "Nah, I mean, I don't need that much help; I've played some video games before."
But he also shows a limited knowledge of operations, acknowledging that the amount of fuel used on take-off was quite a lot more than he expected and that some instructions to him were "mumbo jumbo".
Advised that he try to land at the US Air Force base at McChord Field, he says:
- "Aw man, those guys would rough me up if I tried landing there... Oh, they've probably got anti-aircraft."
The controller asks for a left turn, receiving the reply:
- "This is probably jail time for life, huh? Well I hope it would be for a guy like me."
Among the more odd exchanges, the man discusses
- The co-ordinates for an orca carrying her dead calf on her back which featured in the news last week
- Looking at the view and possibly going to look at the Olympic Mountains in Washington state
- Whether or not Alaska Airlines would give him a job after a successful landing
However, there are also indications that the man might not have been expecting to land safely. He talks of doing a barrel roll before landing and then "calling it a night".
When asked to land he says: "I don't know, man. I don't want to. I was kind of hoping that was going to be it, you know."
He also says: "I've got a lot of people that care about me. It's going to disappoint them to hear that I did this.
"I would like to apologise to each and every one of them. Just a broken guy, got a few screws loose, I guess. Never really knew it, until now."
What did eyewitnesses see?
Ben Schaechter was on a plane which was apparently taxiing down the runway as the stolen plane took off.
"A pilot on the plane in front of us just went rogue and took off on an empty plane bypassing orders from the tower. The tower ordered a full stop and they're trying to communicate with that pilot. Whaaaaaat!"
Okay this insane. A pilot on the plane in front of us just went rogue and took off on an empty plane bypassing orders from the tower. The tower ordered a full stop and they’re trying to communicate with that pilot. Whaaaaaat!— Ben Schaechter (@Bensign) August 11, 2018
Eyewitness John Waldron told CNN he watched the plane do "a complete loop", before it went "pretty much straight up. And kind of at an angle. And almost stalled the aircraft".
"Somehow he got it levelled back off," he told the broadcaster. "And then made his way down toward the island."
Leah Morse, who filmed the jet flying overhead, told Reuters she felt in her "gut something was wrong" after spotting the plane.
Ms Morse's mother, who lives closer to the area where the plane went down, said her whole house shook.
"We saw the jets circle back after and she texted that there was no plane," she added.