An investigation is under way into how an airline employee stole an empty plane, took off from Seattle’s Sea-Tac International Airport and crashed into a small island in the Puget Sound.
The Horizon Air turboprop plane was being chased by military jets that were quickly scrambled to intercept the aircraft.
The bizarre incident involving a worker authorities said was suicidal points to one of the biggest potential perils for commercial air travel – airline or airport employees causing mayhem.
“The greatest threat we have to aviation is the insider threat,” Erroll Southers, a former FBI agent and transportation security expert, told The Associated Press.
“Here we have an employee who was vetted to the level to have access to the aircraft and had a skill set proficient enough to take off with that plane.”
The Friday night crash happened because the 29-year-old man was “doing stunts in air or lack of flying skills”, the Pierce County Sheriff’s Department said.
The man, who was believed to have been killed, was not identified.
There was no connection to terrorism, Ed Troyer, a spokesman for the sheriff’s department, said.
Video showed the Horizon Air Q400 doing large loops and other dangerous manoeuvres as the sun set on Puget Sound. There were no passengers aboard.
Authorities initially said the man was a mechanic, but officials said Saturday that the man was a Horizon employee and had clearance to be among aircraft.
To their knowledge, he was not a licensed pilot.
Those employees direct aircraft for takeoff and gate approach and de-ice planes.
The man used a machine called a pushback tractor to first manoeuvre the aircraft so he could board and then take off, authorities added.
It is unclear how he attained the skills to do loops in the aircraft before crashing about an hour after taking off, they said.
Southers, the aviation security expert, said the man could have caused mass destruction.
“If he had the skill set to do loops with a plane like this, he certainly had the capacity to fly it into a building and kill people on the ground,” he said.
The plane was pursued by military aircraft before it crashed on tiny Ketron Island, southwest of Tacoma, Washington.
Video showed fiery flames amid trees on the island, which is sparsely populated and only accessible by ferry.
No structures on the ground were damaged, Alaska Airlines said.
Troyer said F-15 aircraft took off out of Portland, Oregon, were in the air “within a few minutes”, and the pilots kept “people on the ground safe”.
Sheriff’s department officials said they were working to conduct a background investigation on the man.
The aircraft was stolen at about 8pm.
Alaska Airlines said it was in a “maintenance position” and not scheduled for a passenger flight.
Horizon Air is part of Alaska Air Group and flies shorter routes throughout the US west. The Q400 is a turboprop aircraft with 76 seats.
Pierce County Sheriff Paul Pastor said the man “did something foolish and may well have paid with his life”.
The man could be heard on audio recordings telling air traffic controllers that he is “just a broken guy”.
An air traffic controller called the man Rich, and tried to convince him to land the plane.
“There is a runway just off to your right side in about a mile,” the controller says.
“Oh man. Those guys will rough me up if I try and land there,” the man responded, later adding: “This is probably jail time for life, huh?”
Later the man said: “I’ve got a lot of people that care about me. It’s going to disappoint them to hear that I did this. Just a broken guy, got a few screws loose, I guess.”
Flights out of Sea-Tac, the largest commercial airport in the Pacific Northwest, were temporarily grounded during the drama.
Investigators expect they will be able to recover both the cockpit voice recorder and the event data recorder from the plane.
Royal King told The Seattle Times he was photographing a wedding when he saw the low-flying turboprop being chased by two F-15s. He said he did not see the crash but saw smoke.
“It was unfathomable, it was something out of a movie,” he told the newspaper.