• Alaska Airlines said a San Francisco-bound plane diverted to Portland after an off-duty Alaska pilot tried to interfere with the engines.
• A recording of the incident appeared to show a pilot of the flight say that the person tried to shut the engines down.
• The pilot, 44-year-old Joseph David Emerson, is in custody and has been charged with 83 counts of attempted murder.

An Alaska Airlines flight operated by a subsidiary diverted to Portland International Airport in Oregon on Sunday after an off-duty Alaska pilot traveling in the cockpit tried to disable the engines, the carrier said.

Horizon Air was operating Alaska Airlines Flight 2059, which was flying from Everett, Washington, to San Francisco before it diverted and landed safely, Alaska said Monday. Pilots regularly pick up jump seats in the cockpit to commute.

"The jump seat occupant unsuccessfully attempted to disrupt the operation of the engines," Alaska Airlines said in a statement. "The Horizon Captain and First Officer quickly responded, engine power was not lost, and the crew secured the aircraft without incident."

The off-duty pilot, 44-year-old Joseph David Emerson, is in custody. He was charged with 83 counts of attempted murder, 83 counts of reckless endangerment and a count of endangering an aircraft, according to Multnomah County Sheriff's Office booking records.

Emerson tried to shut down the engines by engaging the fire suppression system, which has a T-shaped handle for each engine and when deployed, will shut a valve that supplies fuel to the engine, according to an airline statement.

The crew reset the handles and the plane's engines didn't lose power, the airline said.

"Our crew responded without hesitation to a difficult and highly unusual situation, and we are incredibly proud and grateful for their skillful actions," Alaska said. 

A recording of the incident from LiveATC appeared to show a pilot of the flight say that the person tried to shut the engines down.

"We've got the guy who tried to shut the engines down out of the cockpit and he doesn't sound like he's causing any issue in the back now," according to the recording. "Other than that we want law enforcement as soon as we get on the ground and parked."

The Federal Aviation Administration said it is "is engaged with Alaska and Horizon airlines and is supporting law enforcement investigations into Sunday evening's incident aboard a Horizon Airlines flight." 

Emerson has been an Alaska Airlines captain since 2019 and became a Virgin Atlantic first officer in 2012. He switched over to Alaska after its acquisition of Virgin in 2016. Alaska said that he completed all his FAA-mandated medical exams and that his certifications weren't denied, suspended or revoked at any point.

The flight's pilots landed the plane safely in Portland and no injuries were reported, Kieran Ramsey, FBI Portland special agent in charge, said in a statement. Ramsey said the FBI "can assure the traveling public there is no continuing threat related to this incident."

Alaska Airlines said all of the passengers were able to get on later flights and that it is reaching out to them individually "to discuss their experience and check-in on their well-being."

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