When does a delay occur if the clearance is not issued?

A delay occurs when air traffic control does not issue a clearance and the aircraft is forced to wait before proceeding with its intended operations. The correct answer is that the delay occurs "when available." This indicates that the aircraft must wait for the proper clearance to be issued to ensure safety and compliance with air traffic control regulations.

In the context of flight operations, the phrase "when available" is understood to mean that once a clearance becomes available, the aircraft will be allowed to proceed. This approach emphasizes the importance of having the appropriate clearances in place before any movements are made, highlighting the critical role that clearances play in maintaining orderly and safe air traffic operations.

The other options do not convey the correct timing of the delay. For instance, stating that the delay occurs by the end of the scenario does not specify when the delay starts, and it suggests a definitive endpoint rather than a dynamic situation based on clearance availability. Similarly, saying the delay occurs when a specific location or time frame (like when SYD is available or when an EDC expires) could misleadingly imply that the delay is contingent on external factors rather than the issuance of the necessary clearance itself. Thus, acknowledging the moment when clearance is available properly frames the nature of the delay in air