The instructions to an aircraft that the pilot make communications transfer at a specified time, fix, or altitude may be omitted when?

The correct answer is based on the principle that when compliance is expected upon receipt, the explicit instructions for communications transfer can be omitted. This approach streamlines communication and allows the pilot to respond promptly without needing to wait for further clarification or repeated instructions.

In situations where the controller and pilot have established a clear understanding—such as during routine operations—it's understood that the pilot will follow the directive upon receiving it. This can be particularly efficient in high-traffic environments where time is crucial, and unnecessary radio chatter is minimized.

The other options involve factors that may influence compliance but do not inherently justify omitting explicit instructions. For example, while a pilot's agreement to comply or confirmation from ground control are important in their own right, they do not negate the requirement for clear instruction at that moment. Similarly, operating under visual flight rules may change the context of flight operations, but it does not directly impact the procedural expectation for communications transfer instructions.