Joseph Emerson, 44, was charged with 83 counts of attempted murder after he allegedly tried to cut off fuel to the engines during a flight from Seattle to San Francisco on Sunday – before being subdued by the flight crew.
The flight was forced to divert to Portland, Oregon after the captain and first officer intervened to keep the engines running.
Passengers who were on board the plane told ABC News that they were not immediately alerted to what Alaska Airlines called the “security threat”, until a flight attendant told them over the speaker that there was “an emergency situation and the plane needed to land immediately”.
Once the plane landed, police boarded the aircraft and arrested Mr Emerson, escorting him off the plane handcuffed.
Bailey Beck, one of the passengers on the plane, told SFGate he saw a man – later identified as Mr Emerson – walk “from the cockpit to the back of the plane by himself, where he was then handcuffed to a railing and didn’t make any disturbance from the rear.”
Aubrey Gavello, another passenger, told Laura Coates Live the suspect was calm and cooperative as he was escorted off the plane.
Mr Emerson’s alleged motive for the incident remains unclear, but passengers said a flight attendant told them he had suffered a mental breakdown.
“After we did land and the gentleman was escorted off, the flight attendant got back on the speaker and said, plain and simple, ‘He had a mental breakdown. We needed to get him off the plane immediately’,’ Aubrey Gavello told ABC.
Authorities confirmed that they do not believe the incident was an act of terrorism or ideologically-motivated violence, but questions still remain after Alaska Airlines said Mr Emerson, who has worked for the company since 2001, did not have a history of medical issues.
“Throughout his career, Emerson completed his mandated FAA medical certifications in accordance with regulatory requirements, and at no point were his certifications denied, suspended or revoked,” Alaska Airlines said in a statement.
The FBI and the Port of Portland police are now investigating the incident.
Records from the Federal Aviation Administration, which is supporting the law enforcement investigation, show the 44-year-old did not hold a certification to fly the ERJ 175 – the type of plane involved in Sunday’s incident.
Alaska Airlines said that Mr Emerson was travelling in the flight deck jump seat in the cockpit when he suddenly tried to shut down both of the plane’s engines by pulling the fire extinguisher handles.
Alaska Airlines confirmed that “all passengers on board were able to travel on a later flight”.
Neighbours of the 44-year-old, who described him as a “friendly” and “fantastic father”, told of their shock after hearing the news.
“He plays with the kids all the time,” Karen Yee told the Daily Mail.
“He’s just a great guy. He’s very understanding of other people,” she said.
“We just couldn’t imagine him doing anything to hurt someone. It’s very hard for us to believe that he would do anything intentionally like that,” she added. “I can’t fathom him doing anything that would hurt anyone.”
Meanwhile, her husband Ed Yee described the incident as “very shocking”.
“He seems like a really nice guy. Nothing abnormal about him,” he told CNN.
Mr Emerson first joined the Alaska Air Group in 2001 as a first officer with Horizon before becoming a pilot with the airline in 2019.