FAA Ground School Practice Test

What does a pulsating red light from a pulsating approach slope indicator indicate?

1. Above glide slope

2. Below glide slope

3. On glide slope

4. Safety alert

The correct answer is: Below glide slope

A pulsating red light from a pulsating approach slope indicator indicates that the aircraft is below the glide slope. This visual cue is designed to alert pilots that they need to climb to reach the proper descent path for landing. When the indicator shows a steady red light instead, it signifies being significantly below the glide slope, which is crucial for maintaining a safe approach and ensuring that the aircraft can land successfully without risking an approach that is too steep or too low. In the context of the glide slope, the indicator provides critical information about the aircraft's position relative to the ideal approach angle. A steady or pulsating white light would indicate being on or above the glide slope, reinforcing the necessity of climbing to meet the appropriate glide path. Understanding these signals is essential for pilots to manage their approach effectively and safely during landing.