Plain English Meaning

Lights beside the runway that tell you, just by their color, whether you are too high, too low, or on the right path as you come in to land.

Full Definition

Ground-based light systems installed near the runway that show a pilot, by colored light signals, whether the aircraft is on, above, or below the correct approach path to the runway. Common types include VASI (Visual Approach Slope Indicator), PAPI (Precision Approach Path Indicator), tri-color systems, pulsating systems, and alignment-of-elements systems.

Context Anchor

You encounter visual glideslope indicators while approaching a runway to land, especially during the part of the .