Which of the following is true regarding aircrew and alcohol consumption?

The statement that alcohol must not have been consumed within 12 hours of takeoff is true and aligns with the regulations that govern aircrew operations. This guideline is critical for ensuring that pilots and crew members are fit to carry out their duties safely. The 12-hour rule is often referred to as the "Bottles to Throttle" rule, emphasizing the need for a significant amount of time to pass after alcohol consumption before engaging in flight operations.

This regulation is based on the effects of alcohol, which can impair cognitive and physical functions necessary for operating an aircraft effectively. By requiring this time frame, the regulation aims to minimize the risk of accidents caused by reduced alertness or impaired judgment, which can be particularly dangerous in aviation.

Understanding this rule is crucial for any aircrew member, as compliance is mandatory for maintaining flight safety and adhering to aviation standards. The other options reference scenarios that either contradict established regulations or do not provide adequate safeguards for crew readiness.