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

When the VASI (Visual Approach Slope Indicator) shows a red light during an approach, it indicates that the aircraft is below the desired glide path. In this situation, the proper response is to execute a missed approach. This ensures that the pilot does not descend further into a potentially unsafe situation, as being below the glide path could lead to obstacles or terrain impacts.

Executing a go-around allows for a safe reset of the approach. The missed approach procedure provides guidance on how to safely return to the proper altitude and align with the approach path for a second attempt. This action also ensures compliance with safety protocols, as continuing the approach in this scenario could lead to dangerous conditions. Thus, the best choice is to go around and execute a missed approach, thereby prioritizing safety and proper adherence to approach protocols.