FAA Ground School Practice Test

What would indicate a slightly high glide slope on a Precision Approach Path Indicator?

1. Two red lights and two white lights

2. Three white lights and one red light

3. All green lights

4. One red light and three green lights

The correct answer is: Three white lights and one red light

In a Precision Approach Path Indicator (PAPI), the configuration of the lights indicates whether an aircraft is above, on, or below the ideal glide slope during an approach. Each light color corresponds to its position relative to the glide slope: white lights indicate that the aircraft is too high, while red lights indicate that the aircraft is too low. For a slightly high glide slope, the indication of three white lights and one red light signifies that the aircraft is above the ideal glide slope but not excessively so. This configuration clearly communicates to the pilot that adjustments need to be made to descend towards the correct glide slope. The other configurations denote different positions: two red lights and two white lights would typically indicate that the aircraft is on the glide slope boundary; all green lights would suggest being well on the glide path, and one red light with three green lights would indicate that the aircraft is slightly below the ideal glide slope.