An off-duty pilot who was riding in the cockpit of an Alaska Airlines flight en route to San Francisco on Sunday is facing dozens of attempted murder charges after he tried to shut down the plane's engines mid-flight, authorities say.
The suspect, identified as Alaska Airlines pilot Joseph D. Emerson, 44, attempted to cut off fuel to the engines but the quick action of the aircraft's captain and first officer kept the engines from failing completely, the airline said, adding Emerson was subdued by the flight crew.
The flight was forced to divert to Portland, Oregon, where the suspect was taken into custody by the Port of Portland police, the port said in a statement.
Emerson has been charged in Oregon with 83 felony counts of attempted murder, 83 counts of reckless endangerment and one count of endangering an aircraft, booking records show.
Authorities do not believe the incident was an act of terrorism or ideologically motivated violence, a law enforcement source familiar with the investigation told CNN's Josh Campbell. The source noted the suspect may face additional federal charges.
Here's what we know.
Suspect tried to cut the engine fuel, airline says
After taking off from Everett, Washington, on Sunday, Alaska Airlines Flight 2059 -- operated by regional carrier Horizon Air -- reported a "security threat related to an off-duty Alaskan Airlines pilot, identified as Captain Joseph Emerson, who was traveling in the flight deck jump seat," the airline said in a statement.
Pilots will sometimes ride in a cockpit "jump seat" when traveling in their official capacity or commuting between airports.
While in the cockpit, Emerson had tried to shut down both of the Embraer 175's engines by pulling its fire extinguisher handles, the airline said.
"The fire suppression system consists of a T-handle for each engine; when pulled, a valve in the wing closes to shut off fuel to the engine," Alaska Airlines said in a statement to CNN. "After they are pulled, some residual fuel remains in the line."
The airline said the quick reaction of the crew to reset both handles helped restore the flow of fuel and prevent the engines from cutting out.
"Our crew responded without hesitation to a difficult and highly unusual situation, and we are incredibly proud and grateful for their skillful actions," the airline said in a statement.
The plane was at cruise altitude when the incident occurred, Capt. Mike Karn, senior manager of flight security for American Airlines, said in a memo circulated at his airline.
The flight crew detained the suspect and the plane was diverted to Portland International Airport, the Port of Portland said in a statement.
"I think he's subdued," one of the plane's pilots can be heard saying in air traffic control audio recorded by LiveATC.net. "Other than that, we want law enforcement as soon as we get on the ground and are parked."
Once the flight landed in Portland around 6:30 p.m., the suspect was taken into custody by Port of Portland police officers, the port said.
No injuries were reported on the flight, the FBI said.
All passengers were later able to fly to San Francisco with a new crew and aircraft, the airline said, noting it is "reaching out to each of them individually to discuss their experience and check-in on their well-being."
The FBI is investigating the incident
Emerson has been detained at the Multnomah County Detention Center as both the FBI and the Port of Portland police investigate the incident, authorities said.
The FBI's Portland field office confirmed its investigation in a statement Monday and assured travelers there is "no continuing threat related to this incident."
The Federal Aviation Administration also said it is supporting local law enforcement in the investigation.
The FAA said it has briefed other airlines on preliminary details of the incident and informed carriers the incident is not related to "current world events" -- apparently referring to the war in the Middle East between Israel and Hamas.
'It was very shocking,' suspect's neighbor says
Emerson's neighbor, Ed Yee, told CNN it was "very shocking" to hear of the suspect's alleged actions.
"He seems like a really nice guy. Nothing abnormal about him," Yee said.
Emerson has worked in aviation for at least two decades, according to information shared by Alaskan Airlines.
He first joined the Alaska Air Group in 2001 as a first officer with Horizon. In 2012, Emerson left Horizon and joined Virgin America as a pilot.
After Alaska Airlines acquired Virgin America in 2016, Emerson became a first officer with Alaska and worked about three more years to become a pilot for the airline, according to the airline statement.
"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.
FAA records show Emerson held an Airline Transport Pilot certification with ratings to fly the Airbus A320, Boeing 737, Canadair Regional Jet, and De Havilland Dash 8. He did not hold a certification to fly the ERJ 175, those records indicate, the type of airplane in use during Sunday's incident.