What is the guideline for aircrews filing at night?

The guideline for aircrews filing at night emphasizes the importance of safety and navigational precision. Filing only if there is an operable straight-in approach with glidepath guidance is critical because it aligns with the higher level of risk associated with nighttime operations. At night, visibility is significantly reduced, making visual references harder to establish. Therefore, relying on an operable approach with glidepath guidance ensures that pilots have a reliable method to navigate and execute their approach safely, reducing the chances of mishaps due to poor visibility.

While the other options could suggest various strategies for flight planning, they do not prioritize the safety measures that come from structured, instrument-based approaches necessary under nighttime conditions. Relying solely on daylight or visual indicators can lead to complications, while broad statements about acceptable routes do not adequately address the specific risks encountered at night. Hence, incorporating glidepath guidance into night flight planning is crucial for safe operations.