Certified Flight Instructor - Flight Instructor Airplane Practice Exam

A slightly low indication on a PAPI glidepath is indicated by?

1. Four red lights

2. One red light and three white lights

3. One white light and three red lights

4. Two red lights and two white lights

The correct answer is: One white light and three red lights

On a Precision Approach Path Indicator (PAPI), a slightly low indication on the glidepath is indicated by one white light and three red lights. The PAPI system is designed to provide visual guidance to pilots during the approach to landing, and the configuration of lights helps identify the aircraft's position relative to the ideal glidepath. In this system, the colors of the lights indicate the aircraft's vertical position relative to the glidepath: the lights change from red to white depending on whether the aircraft is too low, on the proper glidepath, or too high. Specifically, when a pilot sees one white light and three red lights, it signifies that the aircraft is slightly below the optimal glidepath. This is a critical indication for pilots, as it prompts them to adjust their descent to reach the correct glidepath before landing. The other configurations signify different positions relative to the glidepath. For example, seeing four red lights would indicate that the aircraft is too low, and seeing two red and two white lights would indicate that the aircraft is very close to the glidepath but slightly low. In contrast, seeing three white lights generally indicates that the aircraft is above the desired path. Understanding these visual cues is essential for safe landings and effective altimeter management during