Two major airlines, American and Southwest, have postponed plans to resume serving alcohol on flights in an effort to stop a surge of unruly and sometimes violent behavior by passengers who have shoved, struck and yelled at flight attendants. Both airlines announced the policies this week after the latest assault was captured on a widely watched video that showed a woman punching a flight attendant in the face on a Southwest Airlines flight from Sacramento to San Diego on Sunday. The flight attendant lost two teeth in the assault, according to her union, and the passenger, who was identified by the police as Vyvianna Quinonez, 28, has been charged with battery causing serious bodily injury. She has also been barred for life from flying Southwest, the airline said.