FAA Ground School Practice Test

What does a below glide slope indication from a VASI usually appear as?

1. Three white lights

2. Pulsating green light

3. Steady red light

4. Pulsating red light

The correct answer is: Pulsating red light

A below glide slope indication from a VASI (Visual Approach Slope Indicator) system typically appears as a steady red light. When an aircraft is below the recommended glide slope, the indication will show solid red lights, indicating to the pilot that they are too low in their approach. VASI systems are designed to give pilots visual cues about their current vertical position in relation to the desired glide slope. The lights generally are configured to provide a clear indication: when the aircraft is on the glide path, the pilot sees a combination of red and white lights; when above the glide slope, the indication leans more towards white lights. Understanding this system is crucial for maintaining a safe approach to landing, alerting pilots to adjust their altitude as necessary to achieve the correct glide slope. Therefore, when a steady red indication appears, it serves as a warning that corrective action is needed to get back on the proper glide path.