Which of the following best describes 'Open Time' in flight scheduling?

The concept of 'Open Time' in flight scheduling refers to the portions of schedules that remain unassigned after all adjustments and assignments have been made. This scenario typically arises when crew availability does not match the planned flight schedule, or when last-minute changes occur that leave certain flights without assigned personnel. Open Time allows airlines like Frontier Airlines to fill these gaps by enabling crew members to pick up additional flights, ensuring operational efficiency and flexibility as personnel can adjust to real-time needs. By having unassigned portions of the schedule, the airline can optimize staffing and better manage fluctuations in operational demands.