The visual glide path of a VASI provides safe obstruction clearance within what angle from the extended runway centerline?

The visual glide path of a VASI (Visual Approach Slope Indicator) provides safe obstruction clearance within a 10-degree angle from the extended runway centerline. This angle is crucial as it ensures that aircraft following the glide slope can descend safely towards the runway without encountering obstacles that might be in this path. The design of VASI is specifically intended to assist pilots in maintaining the correct approach angle and to ensure a safe landing trajectory. By providing a clear visual reference, it allows pilots to adjust their altitude and approach as needed, making it an essential safety feature in aviation.

Angles wider than this could potentially lead to increased risk of obstructions, while angles narrower than this may not offer adequate visual guidance for pilots during their final descent.