For a One Nav Cat 1 operation, how should the ceiling and visibility minima be adjusted?

• A. Ceiling: Add 400 feet to MDA or DA; Visibility: Add 1 statute mile or 1600 meters
• B. Ceiling: Add 200 feet to MDA or DA; Visibility: Add 1/2 statute mile or 800 meters
• C. Ceiling: Add 400 feet to MDA or DA; Visibility: Add 2 statute miles or 3200 meters
• D. Ceiling: No change; Visibility: Add 1/2 statute mile or 800 meters

Answer: (A)

When you’re performing a One Navigation Cat I operation, you increase the minima because you’re relying on a single navigation source, which reduces redundancy and increases the risk of navigation error or degraded signal. To compensate, the published minimums raise both the vertical and horizontal safety margins: you add 400 feet to the MDA or DA, and you increase visibility by 1 statute mile (which is 1600 meters). The extra vertical margin helps maintain obstacle clearance if the nav signal is less reliable, and the extra visibility gives you more time and room to identify the runway environment and decide whether to continue or execute a missed approach. This combination aligns with standard practice for a single-nav approach, balancing the reduced redundancy with sufficient protection.