What is the visual cue provided by the VASI system?

The VASI, or Visual Approach Slope Indicator, system provides visual descent information to pilots during the approach phase of landing. It is designed to help pilots maintain the correct glide slope during their approach to the runway. The VASI consists of a set of lights that display a visual cue—generally a combination of red and white lights—indicating whether the aircraft is above, below, or on the correct glide path.

When the lights are displayed as all white, this signifies that the aircraft is too high; when they are all red, it indicates that the aircraft is too low. Ideally, a combination of red and white indicates that the aircraft is on the correct glide slope. This visual cue is crucial for ensuring a safe landing, as it assists pilots in judging their descent path accurately, leading to a smoother and safer approach to the runway.

Other options relate to aspects that the VASI system does not provide. For example, air speed limits are determined by the aircraft's performance specifications and flight conditions, not visual cues from the VASI lights. Landing clearance is an authorization granted by Air Traffic Control and is not part of the VASI functionality. Runway length information is provided in approach charts or airport information, rather than through the