When is takeoff not authorized based on weather conditions?

Takeoff is not authorized based on weather conditions when the ceiling is below 1500 feet and visibility is below 3 statute miles. This criterion is important as it ensures that pilots have adequate visibility and sufficient airspace above to safely manage the departure from the runway.

A ceiling below 1500 feet indicates that the cloud layer is relatively low, potentially causing significant visibility issues and increasing the risks of flying into rising terrain or obstacles that could lead to an accident during takeoff. Meanwhile, visibility below 3 statute miles further complicates matters, making it difficult for pilots to navigate and maintain situational awareness during flight operations. The combination of both of these factors represents a substantial hazard to flight safety, thereby prohibiting takeoff until weather conditions improve.

The other options present either one of these elements in less restrictive terms or do not meet the combination required for takeoff restrictions. This understanding is vital for ensuring safe flight operations and adherence to aviation regulations.