What does ATC delay refer to?

ATC delay specifically refers to delays in receiving takeoff or landing clearance from Air Traffic Control. This can occur for various reasons, such as traffic congestion, weather conditions, or other operational considerations that require ATC to manage the flow of air traffic safely and efficiently. When a pilot is waiting for permission to take off or land, they experience an ATC delay that can affect their overall schedule and operational planning. Understanding this concept is crucial for pilots, especially in instrument flying where precision and timing are vital for safety and efficiency in busy airspace.

The other options do not accurately capture the essence of what ATC delay means. For instance, while preflight checks and flight plan filing are part of the overall flight preparation process, they do not involve the direct influence of air traffic control. Additional flight time due to routing is typically related to changes in flight plans or deviations but is not synonymous with ATC delays.