CHICAGO — We’ve all seen them--cellphone videos of people misbehaving on flights and being removed.

This week, Delta Airlines proposed carriers share their no-fly lists of unruly passengers. It’s an effort to protect airline employees across the industry. It comes as flight crews are left to enforce pandemic-era restrictions and bear the brunt of travelers unwilling to comply.

In January, due to the disturbing increase in violent behavior on flights, the Federal Aviation Administration (FAA) enacted a zero-tolerance policy for anyone who “assaults, threatens, intimidates or interferes with airline crew members.”

“Post-pandemic travel is not the same,” said Ron Phifer, supervisory air marshal in charge of the Chicago field office for the Federal Air Marshal Service.

Phifer says FAA mandates like wearing a mask must be enforced on flights by federal law.

“We treat mask requirements very similar to those other safety requirements on board the aircraft, and that's what aircrews are trained to do,” said Phifer.

After a pandemic pause, the TSA resumed self-defense training for crew members this past summer. Taught by federal air marshals, it’s designed to teach them effective defensive measures for use onboard an aircraft or even in public spaces.

“They learn to defend themselves with hand strikes with using their feet, their legs. So, protecting their vital parts of their body,” said Phifer.

Lisa Hodo has been a flight attendant for more than 30 years and finally decided to take the class.

“Flight attendants have been the subject of attacks,” she said. “I mainly, I came so that I could protect myself as well as my passengers on the plane.”

Hodo says enforcing federal mask mandates has been a real challenge.

“Even though they have signed the agreement, that they're going to keep wearing the masks, they don't necessarily want to do it,” said Hodo.

So far this year, the FAA has documented nearly 4,500 reports of unruly passengers and close to 3,300 mask-related incidents.

Flight attendant and instructor Barbara Aievoly, another first-time self-defense trainee, says it’s important now more than ever to be prepared for a confrontation.

“No matter what's going on, everyone knows it's going to be filmed. And I don't want to be famous for, you know, having to handle an unruly passenger,” said Aievoly. “I'd like to de-escalate at first. But I also want to know the proper way to get out of a situation that I might not be able to handle.”

Penalties for unruly behavior have been upped with a fine of up to $37,000 or criminal charges. The FAA’s already initiated 169 enforcement cases this year and collected more than $1 million in fines.

Hodo says she hopes those deterrents will work.

“You just don't want to escalate it. That's the main thing," Hodo said. "You don't really want to have to move to the things that we're being taught in here.”