According to a federal affidavit seen by The Independent, Mr Emerson told police that he had suffered a “nervous breakdown” and had been taking psychedelic mushrooms.
Mr Emerson explained to the officers: “I didn’t feel okay. It seemed like the pilots weren’t paying attention to what was going on. They didn’t… it didn’t seem right.”
Mr Emerson appeared at a brief hearing at a court in Oregon on Tuesday, where he entered pleas of not guilty to all charges against him, via his attorney. He is due to return to court on Wednesday morning for a preventative detention hearing.
He faces a total of 167 state charges – 83 counts of attempted murder, 83 counts of reckless endangerment and one count of endangering an aircraft.
The incident occurred on Sunday during a flight from Seattle to San Francisco. Authorities said Mr Emerson was travelling in the flight deck jump seat in the cockpit when he suddenly tried to shut down both of the plane’s engines by pulling the fire extinguisher handles.
He was then subdued by flight crew as the captain and first officer intervened to keep the engines running. Mr Emerson was escorted by a flight attendant to the rear of the aircraft where he was placed in wrist restraints and belted into the aft jump seat.
According to Alaska Airlines Mr Emerson also attempted to grab the handle of the emergency exit during the aircraft’s descent before being stopped by a flight attendant.
The flight was diverted to Portland, Oregon, due to the “credible threat” posed by Mr Emerson and he was arrested upon arrival. His exact motive for his actions remain unclear, though authorities do not believe the incident was an act of terrorism or ideologically-motivated violence, CNN reported.
Prior to the incident Mr Emerson was a pilot with Alaska Airlines. According to the airline he joined Alaska Air Group as a Horizon First Officer in August 2001.
In June 2012, Mr Emerson left Horizon to join Virgin America as a pilot but became an Alaska Airlines First Officer following Alaska’s acquisition of Virgin America in 2016. He became an Alaska Airlines Captain in 2019.
Alaska Airlines said that following the incident Mr Emerson had been removed from service indefinitely and relieved from all duties at the airline. The company said it was now consulting with its partners in labour regarding his employment status.
In a previous statement the airline said Mr Emerson did not have a history of medical issues and had completed mandatory FAA medical certifications throughout his career.