Alaska Airlines cabin crew used a beverage cart to stop a passenger trying to enter the cockpit, prosecutors say

• An Alaska Airlines passenger tried three times to access the cockpit, an affidavit says.
• Flight attendants blocked the door with a beverage cart, it adds.
• The defendant's lawyer asked the judge for a mental competency evaluation.

An Alaska Airlines cabin crew blocked the cockpit with a beverage cart to stop a passenger from accessing the flight deck, an affidavit states.

Nathan Jones was flying from San Diego to Washington, DC, on March 3 when he made three attempts to open the cockpit door, per the court document.

The affidavit, seen by Business Insider, is based on an investigation from an FBI officer who's also a federal air marshal with the Transportation Security Administration.

Jones was restrained with flex cuffs by off-duty law enforcement officers who sat on either side of him for the rest of the flight, the affidavit says.

It adds that when a flight attendant asked why he was trying to get into the cockpit, Jones replied he "was testing them."

The flight deck was locked down for the rest of the flight, and one flight attendant stayed with the beverage cart blocking the cockpit door, per the affidavit.

When the plane landed, agents searched Jones' luggage and found his student pilot's license as well as notebooks describing how to operate an aircraft, the court document says.

Jones was charged with one count of interference with a flight crew the day after the incident.

On Wednesday, his lawyer submitted a motion for a mental competency evaluation.

A letter from the senior therapist responsible for the jail where Jones is detained said he was displaying "symptoms indicative of a serious mental illness."

Alaska Airlines did not immediately respond to a request for comment from BI, sent outside normal working hours.