In the US pilots are not allowed to fly with ANY alcohol in their system! If a pilot is tested on a breathalyzer and blows even 0.01% he is automatically put out of service for the next 8 hours. 0.04% BAC is considered legally intoxicated by the FAA (half what it is for drunk driving) and anyone caught attempting to fly with 0.04% or higher is subject to arrest for DUI.