What is the minimum weather condition for a departure?

The minimum weather condition for a departure, particularly when looking at the requirements for a safe takeoff, is often governed by regulations that dictate visibility and runway conditions. A reported Runway Visual Range (RVR) of 4,000 feet or less represents a specific measurement that indicates the horizontal distance a pilot can see down the runway. Meeting or exceeding this RVR ensures that pilots have adequate visibility to make informed and safe decisions during takeoff.

It is crucial to comply with these guidelines, as they are based on safety considerations, ensuring that aircraft can achieve safe operational standards under various conditions. Option D reflects a standardized metric that can be uniformly measured, providing a clear benchmark for departure safety, thereby contributing to effective risk management in flight operations.

Other options mention general visibility conditions or ambiguous parameters which may not be as universally applicable or measurable. Therefore, aligning with the specific requirement of reported RVR of 4,000 feet or less is fundamental to ensuring aircraft can safely navigate the initial phases of flight.