"The Transport Canada rule is eight hours, but we have
that additional buffer for safety reasons. The bottom line is that
pilots are not supposed to have a drink for 12 hours before they
operate an aircraft."
Source: Air Canada
spokesperson, Peter Fitzpatrick, explaining the regs around
alcohol consumption for the airline, as well as for Transport
Canada... after one of the airline's pilots was removed from a B777
flight on suspicion of alcohol abuse.