United Airlines has extended the pre-flight alcohol ban for pilots from a minimum of eight hours to a minimum of 12 hours after two of its pilots were arrested in Scotland suspected of being over the legal limit before a flight back to the US.
The flight was cancelled and one of the pilots was later charged.
The minimum eight-hour limit is imposed by the US air safety authority, the Federal Aviation Administration.
"This policy is being changed to help assure pilot compliance with standards established by the United States and individual states where United operates around the world," the airline wrote in an employee memo.
The new limit took effect last week.
"Inappropriate alcohol use by airline pilots is exceedingly rare," the Air Line Pilots Association said.
Earlier this month a flight attendant was arrested and later fired after slurring her words during the pre-flight safety demonstration. She was then photographed passed out in a jump seat.
In July a Delta pilot was arrested before a flight in Minneapolis in possession of alcohol on duty.
Delta, American and Southwest Airlines all follow the FAA’s eight-hour cut-off limit and none have so far said they are considering extending it.
Alaska Airlines has a 10-hour no-booze period before a flight.
