Observing aids for visibility must be clearly identified as daytime or nighttime aids and updated at least how many times?

• A. Daily
• B. Weekly
• C. Annually
• D. Monthly

Answer: (C)

Observing aids for visibility must be categorized clearly as daytime or nighttime and kept current on a regular, formal update cycle. The point is to ensure the designation matches actual conditions and equipment so aircrews and ground personnel aren’t relying on outdated guidance. Updating at least annually provides a practical balance between keeping information fresh and avoiding unnecessary administrative burden, while still allowing for review of any changes in lighting, materials, or procedures. More frequent updates (daily, weekly, or monthly) would imply changes that don’t typically occur that often and could create confusion if updates aren’t synchronized.