By David Shepardson WASHINGTON (Reuters) -A total of 80 unruly airplane passengers have been referred to the FBI for potential criminal prosecution, the Federal Aviation Administration (FAA) said on Wednesday, as onboard disruptions rose sharply in 2021, many over COVID-19 mask requirements. The U.S. Justice Department has pledged to take a tough line and some airlines and labor unions have called for a “no-fly” list that would ban passengers with a record of disruptions. The increase in cases is tied to pandemic restrictions that have prompted friction on airplanes. The FAA, which said last y…