The FAA has already investigated more than 600 unruly-passenger incidents in 2021 - nearly double the combined total from 2019 and 2020

• The FAA last week said it'd investigated more than 600 reports of unruly passenger behavior in 2021.
• That's nearly double the combined number of investigated incidents in 2019 and 2020.
• The agency said it had proposed fines in 99 of those incidents thus far.

Whether by shirking mask requirements or assaulting flight attendants, airline passengers are acting up in extreme ways and at alarming rates in 2021.

Last week, the Federal Aviation Administration said airlines had reported 3,715 incidents of unruly passengers this year, more than 75% of which involved reports of people refusing to wear federally required face masks on planes.

Of the nearly 4,000 reported incidents, the FAA said it had started investigating more than 600 - nearly double the combined number it investigated in 2019 and 2020, according to the Associated Press.

The agency said it had proposed fines in 99 of those incidents.

Earlier this year, the FAA began cracking down on unruly passengers in an attempt to assuage the rampant misbehavior that seemed to spike during the coronavirus pandemic. In May, the agency proposed a combined $100,000 in fines for just four passengers who refused to follow the rules.

Then, last week, the agency sent a letter to US airports asking for help protecting travelers and flight attendants from disorderly passengers. The FAA, which prohibits passengers from drinking alcohol on planes that isn't served by the airline, asked airports to bar travelers from bringing to-go cocktails from airport bars on aircraft.

The FAA chief, Stephen Dickson, also asked local police officers to help hold unruly passengers accountable. While the agency has proposed civil fines for dozens of passengers this year, Dickson stressed that the FAA had no authority to file criminal charges.

In a survey of 5,000 flight attendants conducted by the Association of Flight Attendants-CWA union earlier this year, more than 85% of respondents said they had dealt with unruly passengers this year. Sixty-one percent reported having heard racist, sexist, or homophobic slurs during altercations, and 17% said they had experienced a physical incident in the first half of 2021.

Five flight attendants told Insider's Allana Akhtar that they wanted passengers to stop directing anger toward them. The airline employees attributed the rise in unruly behavior to a heated political climate and fear and anxiety stemming from a year and a half of COVID-19.

The 3,715 unruly incidents reported by airlines in 2021 so far already mark a nearly threefold increase from past years, and there are still 4 1/2 months left in 2021.