A Californian woman has pleaded guilty to punching a flight attendant in the face, bruising her and chipping three of her teeth, during an argument over replacing her mask and other air safety requirements.
Vyvianna Quinonez of Sacramento had initially claimed she was acting in self-defence, before accepting on Wednesday the federal charge of "interference" of a flight, which carries a maximum penalty of 20 years in prison and a $250,000 fine.
The incident took place on May 23, when Quinonez's Southwest Airlines flight began its descent into Sacramento, the plea agreement said.
The flight attendant asked Quinonez to fasten her seatbelt, stow her tray table and reposition her mask so that it covered her mouth and nose.
In response, Quinonez pushed the flight attendant and then began "punching her in the face and head with a closed fist and grabbing her hair", the agreement said.
Court documents show she then told police officers who came aboard for her arrest that she was only acting in self-defence, which was disproven by other passengers' videos.
"The flight attendant who was assaulted was simply doing her job to ensure the safety of all passengers aboard the plane," said Randy Grossman, a federal prosecutor in California.
The prosecutor's office said it intended to ask for a jail sentence of four months and six months of house arrest.
Quinonez will also be banned from flying for three years.
"We appreciate the efforts of federal and local authorities working to bring this case to justice," Southwest Airlines told AFP.
"Southwest Airlines has a zero-tolerance policy when it comes to physical or verbal abuse against its employees."
Incidents involving agitated or violent passengers have risen sharply in the US since the start of the Covid-19 pandemic, largely fuelled by passengers refusing to wear a mask.
Last week, a man was forced to leave a flight in Florida for wearing a red thong as a face mask.
The FAA said more than 5,664 incidents were reported in 2021, of which more than 4,000 were related to masks.
As of August 2021, the FAA had recommended over $1 million in fines for unruly passengers.