A Sacramento, California, woman has pleaded guilty to punching a Southwest Airlines flight attendant over masking and other COVID-19 safety requirements, federal prosecutors announced Thursday.The flight attendant was punched so hard that three of her teeth were chipped, her face was badly bruised and she needed stitches, according to a statement from the U.S. Attorney’s Office for the Southern District of California. The attack in May on a flight to San Diego was captured on video by another passenger.Vyvianna Quinonez, 28, admitted she intentionally punched the flight attendant in the face and head with her fist and grabbed her hair, according to the U.S. attorney’s office. She initially claimed she was acting in self-defense.Quinonez could face up to 20 years in prison and a $250,000 fine. Prosecutors are seeking four months in prison, an additional seven months of home confinement and a three-year ban on air travel.The violence was reportedly triggered when Quinonez was given instructions during the flight’s final descent into San Diego. She was not wearing her face mask “properly, [had] unbuckled her seat belt, and pulled down her tray table — all in violation of federal rules and regulations,” noted the federal prosecutors’ statement.Quinonez struck out when the flight attendant approached her again.Another passenger stepped in between the two women to stop the assault.The flight attendant was “simply doing her job to ensure the safety of all passengers aboard the plane,” Acting U.S. Attorney Randy Grossman said in a statement. “It’s inexcusable for anyone to use violence on an airplane for any reason, particularly toward a flight attendant who is there to keep all the passengers safe. We are not going to tolerate violence or interference with the flight crew, and we will pursue criminal charges against those who break the law.”Southwest Airlines also released a statement: “We appreciate the efforts of federal and local authorities working to bring this case to justice. Southwest Airlines has a zero tolerance policy when it comes to physical or verbal abuse against its Employees.”The attack was one of 5,779 “unruly passenger reports” filed with the Federal Aviation Administration this year as of Tuesday. Nearly 4,200 of the incidents were linked to wearing masks, mandated on aircraft to protect the health of all flyers.