Several US airlines have reported that a growing number of unruly passengers have spat on other passengers, attacked flight crews and, in one case, even tried to open a door midflight as more people fly again after the worst of the pandemic in the United States.

This year, the Federal Aviation Administration, or FAA, had reported 3,509 incidents of passengers behaving badly by mid-July. At least 85 Transportation Security Administration, or TSA, agents have been attacked at checkpoints, two on Monday. The FAA has opened cases into 581 of the incidents.

This year's air-rage incidents are up from those reported in 2020, when the agency launched investigations into 183 unruly passengers. In 2019, it was 146.

Some 2,605 of the disturbances have been caused by passengers who wouldn't comply with federal law that a mask be worn on airplanes during the pandemic, according to the Association of Flight Attendants.

The FAA fined a passenger $10,500 this month for refusing to follow the mask mandate on a flight in February.

Darby LaJoye, the TSA's acting administrator, told a House of Representatives Homeland Security subcommittee on Tuesday that 25 of 85 assaults had been reported since May. Last month, a passenger in Denver bit two TSA officers.

It has become so bad that flight attendants are being retrained in key self-defense techniques.

Sara Nelson, president of the Association of Flight Attendants, said in a June letter to the Centers for Disease Control and Prevention and the TSA:"This year, the rate of documented disruptive passenger incidents is at an all-time high and just last week TSA announced that, starting in July 2021, it will resume its voluntary classes in self-defense training for flight attendants and pilots.

"Union safety representatives consistently report that most disruptive passenger incidents currently involve noncompliance with mask policies, and often a contributor to the incidents is alcohol consumption."

The FAA rolled out a zero-tolerance policy in January after a spate of violent incidents on airplanes. The agency said that it historically had dealt with unruly passengers with a variety of methods, ranging from warnings and counseling to civil penalties.

Zero-tolerance

On July 6, the FAA assessed $119,000 in civil penalties against passengers for alleged violations of federal regulations as part of its zero-tolerance effort.

At least nine passengers were hit by fines ranging from $7,500 to $21,500 for allegedly interfering with flight attendants who instructed passengers to obey cabin crew instructions and federal regulations.

The cases involved "assaulting the flight crew and other passengers, drinking alcohol brought aboard the plane and refusing to wear face masks".

On July 6, a passenger on an American Airlines flight was duct-taped to her seat after she allegedly attacked the flight crew and tried to open the door of the aircraft in midflight. In a stark video posted to social media, the woman can be seen with tape over her mouth and arms.

Witnesses said that the woman had become unruly about an hour into the two-hour flight.

Wearing a mask in the US to combat COVID-19 became highly political during the presidency of Donald Trump.

Marjorie Taylor Greene, a Republican US representative from Georgia, compared mask wearing in the House to the ways Nazis controlled Jewish people during the Holocaust.

The TSA will enforce the mask mandate on airplanes until mid-September.

Nelson said:"Masks not only help to protect more vulnerable passengers from the Delta variant, but they also help to protect passengers and crew members who are unable to get vaccinated for valid medical reasons－but still need to fly."