Off-duty pilot tried to shut down plane's engines during flight—airline

An off-duty Alaska Airlines pilot who was sitting in a cockpit jump seat on a US commercial flight has been charged with attempted murder after allegedly trying to shut down the plane's engines in flight.

The Horizon Air Embraer E-175 was on a flight from Everett, Washington, to San Francisco when the incident occurred on Sunday, Oct. 22, Alaska Airlines, the parent company of Horizon, said in a statement.

The plane, which was carrying 80 passengers, was diverted to Portland, Oregon, where it landed safely.

Alaska Airlines said the Horizon Air pilots reported a "credible security threat related to an off-duty Alaska Airlines pilot who was traveling in the flight deck jump seat."

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

"We are grateful for the professional handling of the situation by the Horizon flight crew and appreciate our guests' calm and patience throughout this event," the airline added.

Alaska Airlines did not identify the off-duty pilot but Joseph Emerson, 44, was charged on Monday, Oct. 23 by the Multnomah County Sheriff's Office in Portland with 83 counts of attempted murder, reckless endangerment, and endangering an aircraft.

Live ATC, a website that archives conversations between pilots and air traffic controllers, published an audio recording of the Horizon Air pilot relating the incident to air traffic control.

"We've got the guy that tried to shut the engines down out of the cockpit," the Horizon Air pilot said. "And he doesn't sound like he's causing any issue in the back right now.

"I think he's subdued. Other than that, yeah, we want law enforcement as soon as we get on the ground and parked," the pilot said.

The pilot described the incident as a "Level 4" threat, one which involves an "attempted or actual breach of the flight deck."

Many airlines routinely allow off-duty pilots to hitch a ride on the cockpit jump seat located behind the pilots.

The Federal Aviation Administration said it was supporting law enforcement investigations into the incident.

A Germanwings plane on a flight from Barcelona to Dusseldorf was intentionally crashed by a pilot in March 2015, killing all 144 passengers and six crew members on board. (AFP)