What is the next action if the VASI shows a red light during an approach?

When the Visual Approach Slope Indicator (VASI) displays a red light, it indicates that the aircraft is below the ideal glide path for landing. This suggests that the approach is too low, which can be dangerous and may lead to landing short of the runway or colliding with obstacles. As a response to this indication, the correct action is to go around and execute a missed approach.

Executing a missed approach allows the pilot to safely gain altitude and reposition the aircraft to attempt another approach, ensuring that the approach is properly aligned with the glide path and avoiding potential hazards associated with being too low. This procedure is critical for maintaining safety during the landing phase and ensures that the pilot can reassess conditions before attempting to land again.