An unruly passenger on a Delta flight in December is now facing the largest proposed fine from the Federal Aviation Administration this year — a whopping $52,500.

According to the agency, the passenger tried to open the cockpit door on the flight from Honolulu to Seattle before striking a flight attendant in the face and pushing them to the floor.

Flight attendants and another passenger on the flight managed to place plastic handcuffs on the unruly passenger, but he later freed himself and managed to hit the flight attendant in the face a second time.

The FAA said police boarded the plane after it landed in Seattle and took the passenger into custody.

“Federal law prohibits interfering with aircraft crew or physically assaulting or threatening to physically assault aircraft crew or anyone else on an aircraft,” the agency said.

The FAA said there have been more than 1,300 unruly passenger cases since Feb. 1. The agency initiated approximately 20 enforcement cases.

“The number of incidents and rate of incidents per 100,000 passengers is up sharply since the beginning of December 2020,” the FAA said in a statement to ABC News last month.

FAA Chief Steve Dickson, in January, first signed the order directing the agency to take a “zero-tolerance policy” in unruly passenger cases — handing down stricter punishments without a warning, including fines of up to $35,000 and imprisonment.

Dickson extended the FAA’s unruly-passenger zero-tolerance policy in March.

“The number of cases we’re seeing is still far too high and it tells us urgent action continues to be required,” Dickson said.

A passenger who faces a civil penalty for unruly behavior has a number of options, according to the FAA, including paying the full penalty or contesting it.