The commonly called ‘ATC Slot’ message is provided by Air Traffic Control in order to delay an aircraft departure time, when necessary for regulation reasons. The CTOC (Calculated Takeoff Time) will be the new identified, planned time. Understandably, passengers do not like ATC slot restrictions, as they often cause delay. However, they are provided for the safety of air traffic and can sometimes improve over time as Air Traffic Control will always try to accommodate traffic as much as possible.