United Airlines is setting an earlier cut-off time for when pilots must stop drinking alcohol before flights.

The airline is telling pilots they must abstain from alcohol for 12 hours before flights, up from the previous eight hours.

The change in the rule — it's called "bottle-to-throttle" in the airline business — comes several days after two United pilots were arrested in Scotland and charged with suspicion of being under the influence before a flight to the U.S.

The old 8-hour limit complied with Federal Aviation Administration rules, which also prohibit pilots from flying with a blood-alcohol content at or above 0.04%. Almost all states make it a crime to drive a car at or above 0.08%.

An extra four hours will help social drinkers sober up, although it might not be long enough for a heavily drunken person. Some researchers calculate that once someone puts down the bottle, their blood-alcohol level drops 0.015% each hour. At that rate, a drinker could go from 0.12% to zero in eight hours, or from 0.18% to zero in 12 hours.

United sent a bulletin describing the new policy to pilots a week ago, and it took effect last Saturday.

"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 bulletin said. It warned that meeting the 12-hour ban doesn't guarantee that pilots will be in the clear — some countries have a zero-tolerance policy on blood-alcohol content.

The Air Line Pilots Association, which represents United's pilots, did not respond to phone and email requests for comment.

A United spokesman declined to say whether the change was due to the arrests of two United pilots on Aug. 3 in Glasgow, Scotland, before they were scheduled to operate a flight to Newark, New Jersey. The flight was canceled.

Spokeswomen for Southwest Airlines and Delta Air Lines said their airlines follow the FAA's current standard of no drinking within eight hours of duty. Neither indicated a change in the works. American, Alaska and JetBlue did not immediately describe their policies.

United's new policy was first reported by Skift, a travel industry media company.

The arrests of the United pilots followed other recent incidents. In May, an American Airlines pilot received a suspended six-month sentence after pleading guilty in a U.K. court to drinking before a Manchester to Philadelphia flight. In July, a Delta Air Lines pilot was arrested before a flight in Minneapolis — airport police said he had an alcoholic container in his possession.

Incidents involving alcohol and on-duty airline employees aren't limited to pilots. On Aug. 2, a flight attendant was arrested after a United Express flight landed in Indiana. Passengers said she slurred her words during the pre-flight safety demonstration, then passed out in her jump seat.