Certified Flight Instructor - Flight Instructor Airplane Practice Exam

When is a VASI system most effective for a pilot during approach?

1. In clear weather conditions

2. At night with lights turned off

3. Under cloudy conditions

4. When transitioning to final approach

The correct answer is: Under cloudy conditions

The VASI (Visual Approach Slope Indicator) system is designed to provide pilots with a visual reference to ensure they are on the correct glide slope during their approach to landing. While the system can be useful in various weather conditions, its effectiveness is most pronounced under cloudy conditions. In cloudy weather, the VASI system helps pilots determine whether they are approaching the runway at the correct angle, especially when visibility is limited. The VASI lights indicate whether the aircraft is too high, too low, or on the proper approach path, providing critical guidance that helps maintain a safe descent. This is particularly important in low visibility situations where natural indicators like the horizon may be obscured. In contrast, during clear weather conditions, pilots can often use visual cues from the terrain and airport layout for guidance, reducing the reliance on the VASI system. At night with the lights turned off, the VASI would not function as intended, making it ineffective. Finally, while the system is beneficial when transitioning to final approach, its true value is maximized under conditions where visual references are limited, such as overcast skies.