Pilots on a regional passenger jet say a 3rd person in the cockpit tried to shut down the engines

FILE - A woman waits for a Horizon Air employee to issue her a shuttle pass for ground transport after her flight was cancelled, Wednesday, Sept. 12, 2007, at Seattle-Tacoma International Airport in Seattle, Wash. A pilot riding in the extra seat in the cockpit of a Horizon Air passenger jet tried to shut down the engines mid-flight and had to be subdued by the two pilots. (AP Photo/The News Tribune, Drew Perine)

PORTLAND, Ore. -

A pilot riding in the extra seat in the cockpit of a Horizon Air passenger jet tried to shut down the engines mid-flight and had to be subdued by the two pilots.

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Authorities in Oregon identified the man as Joseph David Emerson, 44. He was being held Monday on 83 counts each of attempted murder and reckless endangerment and one count of endangering an aircraft, according to the Multnomah County Sheriff's Office.

The San Francisco-bound flight on Sunday diverted to Portland, Oregon, where it was met by officers from the Port of Portland, who took Emerson into custody.

Alaska Airlines, which owns Horizon, a regional carrier, said Monday that the crew reported "a credible security threat related to an authorized occupant in the flight deck jump seat." The airline said in a statement that no weapons were involved.

One of the pilots told air traffic controllers that the man who posed the threat had been removed from the cockpit.

"We've got the guy that tried to shut the engines down out of the cockpit. And he -- doesn't sound like he's causing any issue in the back right now, and I think he's subdued," one of the pilots said on audio captured by LiveATC.com. "Other than that, we want law enforcement as soon as we get on the ground and parked."

The FBI office in Portland said it was investigating "and can assure the travelling public there is no continuing threat related to this incident."

The Federal Aviation Administration said it was helping law enforcement investigations, but declined further comment about the incident.

According to FAA records, Emerson holds a license to fly airline planes. It was not immediately certain which airline he works for.

The incident occurred on a 76-seat Horizon Air Embraer 175 that left Everett, Washington, at 5:23 p.m. local time and landed in Portland an hour later. Alaska Airlines did not immediately say how many passengers were on board.

When the jump seat, a third seat in the cockpit, is occupied it's often filled by an off-duty pilot, but the seat can be used by other airline employees or federal safety inspectors.

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Koenig reported from Dallas.