When must ZAE transfer communications to GWO TWR?

Transferring communications prior to entering the surface area is essential for maintaining proper air traffic control procedures and ensuring safety within the vicinity of the airport. This transfer is crucial as it allows the tower control to take over the responsibility of the aircraft as it approaches the airport, ensuring that the aircraft is guided appropriately through the airspace and aligned with other arriving and departing flights.

In this context, the surface area refers to the controlled airspace that extends up to a specific altitude around the airport where the tower has the responsibility for managing traffic. By requiring that communications be transferred before the aircraft enters this area, it helps ensure a clear handover where the tower can provide local air traffic information, instructions, and any necessary clearances pertinent to landing or takeoff.

The other options might not specify the critical safety aspect of timing this transfer correctly. For instance, transferring communications at a specific distance when the aircraft is 10 miles out could lead to situations where the aircraft is not adequately prepared to enter the controlled airspace. Similarly, transferring immediately after takeoff or only during emergencies misses the proactive communication management necessary for safe operations.