The lawsuit, which also names Horizon Air as a defendant, stems from an in-flight emergency declared by the crew of Alaska Airlines Flight 2059 over the Pacific Northwest while the aircraft was en route from Everett, Washington, to San Francisco, on Oct 22.

The Alaska Airlines flight was operated by the group's regional subsidiary Horizon Air.

The suit was filed in Washington state court as a proposed class-action complaint on behalf of all those who flew as passengers aboard the aircraft.

Alaska Airlines and the law firm The Stritmatter Firm did not immediately respond to requests for comment.

The passengers in the lawsuit have asked for a public explanation from Alaska Air and Horizon Air as to why the pilot was not subjected to preflight security screening.

The lawsuit is seeking special and general damages in amounts to be proved at a trial, including ticket fees, damages for psychological injury, physical pain and suffering among others.

The suit also seeks injunctive relief mandating Alaska Airlines and Horizon Air to conduct examinations of all anticipated flight crew and jump seat passengers, including their "mental health status".

Joseph David Emerson was the Alaska Airlines pilot who was riding as a standby employee passenger in the cockpit "jump seat". According to court documents, Emerson told police he had struggled with depression for the past six months and had taken "magic mushrooms" about 48 hours before boarding the plane.

Emerson ended up restrained by members of the cabin crew and was arrested in Portland, Oregon, where the flight was diverted and landed safely. The 44-year-old was charged with 83 counts of attempted murder - one for every person aboard the plane besides himself - and a single count of endangering an aircraft.

(Reporting by Steve Gorman in Los Angeles; Reporting by Abinaya Vijayaraghavan and Shubhendu Deshmukh in Bangalore)

By Steve Gorman