A flight bound for San Francisco has been diverted to Portland, Oregon, after a jump seat passenger in the cockpit tried to disable the aircraft engines.

Alaska Airlines Flight 2059 operated by Horizon Air from Everett, Washington, diverted on Sunday (local time) after reporting a credible security threat, the airline said in a statement.

The Federal Aviation Administration told airlines in a notice seen by Reuters the man tried to disable the engines on the Embraer 175 regional jet by deploying the fire suppression system. It said the crew was able to subdue the individual and remove him from the flight deck.

“I’ll just give you a heads-up. We’ve got the guy that tried to shut the engines down out of the cockpit,” the pilot told FAA air traffic control, according to audio posted by LiveATC.

“It doesn’t sound like he’s causing any issue at the back. I think he’s subdued … We want law enforcement as soon as we get on the ground and parked.”

A 44-year-old man was booked on 83 counts of attempted murder and endangering an airplane, according to Multnomah County Sheriff’s Office booking information.

The Seattle Times identified the passenger as an off-duty Alaska Airlines pilot.

The FAA told airlines in a separate notice on Monday the incident was “not connected in any way, shape or form to current world events” but said it is “always good practice to maintain vigilance”.

-AAP