The Federal Aviation Administration today said it has referred 43 unruly passengers to the FBI for criminal investigation over the past year, as it continues its zero-tolerance policy over serious onboard incidents.

The rate of unruly passenger incidents has fallen by over 80% since record highs in early 2021, the FAA said. U.S. Attorney General Merrick Garland directed the FBI to prioritize investigations of airline passengers committing assaults following a 500% spike in incidents in 2021.

The new cases bring the total of such referrals for violent and threatening behavior on planes to 313 since late 2021.

The FAA in 2022 said its crackdown on unruly passengers would become permanent even after the end of a mask mandate tied to most of the earlier reported incidents.

Reported unruly passenger incidents in 2021 jumped to 5,981, which included 4,290 mask-related incidents and has fallen to 1,375 so far this year. The FAA proposed $5 million in fines in 2021 and $7.5 million last year.

Last month, an American Airlines passenger was indicted in Utah after attempting to open the aircraft exterior doors mid-flight.

Eric Gapco, 26, of New Jersey, was accused of assaulting and intimidating a flight attendant and flight crew on a July 18 flight from Seattle to Dallas that was forced to divert to Salt Lake City.

The Justice Department said the passenger propositioned a flight attendant for sex, locked himself in the lavatory, and attempted to open the aircraft exterior doors multiple times while the aircraft was in flight and was restrained by flight crew members and other passengers with flexible restraints. Gapco has pleaded not guilty and is awaiting trial.

In 2023, a bipartisan group of lawmakers made a new push for legislation to bar passengers fined or convicted of serious physical violence from commercial flights, arguing enhanced penalties are a strong deterrent needed to improve aviation safety.