What is the maximum distance from the airport within which communications must be established?

The correct answer is that communications must be established within a maximum distance of 4 nautical miles (nm) from the airport. This requirement is essential for ensuring safety and operational effectiveness during the critical phases of flight, particularly during takeoff and landing.

Establishing communication within this range allows air traffic controllers to maintain oversight of unmanned aircraft systems (UAS) that are operating near airports, thus facilitating coordination with manned aircraft and ensuring safe separation between different aircraft. This proximity is crucial for responding to any potential issues or emergencies that might arise as an aircraft approaches the airport environment.

Understanding the importance of this distance emphasizes the need for clear communication with air traffic control, especially in controlled airspace, where the risks associated with interactions between different aircraft types are higher.