What defines a calendar day in aviation?

A calendar day in aviation is defined as a 24-hour period that runs from 0001 (12:01 AM) to 2400 (midnight of the following day) in local time. This definition is crucial for maintaining standardization across scheduling, operations, and regulatory compliance within the aviation industry. It allows for clear and consistent planning for flight crews, aircraft operations, and passenger itineraries, ensuring that everyone involved has a common understanding of timeframes.

The concept of a 24-hour day aligns with international practices, facilitating coordination between different airlines and regulatory bodies. It also simplifies the calculation of duty times, rest periods, and other operational parameters essential for safety and efficiency in aviation operations. The clear delineation of a calendar day minimizes confusion that may arise from varying interpretations of shorter or longer time frames.