Which system helps maintain the optimal approach angle for landing?

The Precision Approach Path Indicator (PAPI) is a visual guidance system that helps pilots maintain the correct approach angle during landing. It consists of a series of lights installed beside the runway that indicate whether the aircraft is above, below, or on the optimal glide slope. Pilots align their approach based on the color of the lights; typically, a combination of red and white lights indicates the aircraft is on the correct path. When the correct angle is maintained, it enhances safety and ensures a smoother landing.

While other systems like the Instrument Landing System (ILS) and Precision Approach Radar (PAR) also aid in landing, they focus on different aspects of the approach, such as providing lateral and vertical guidance using instruments or radar. The Distance Reference Drop-off Framework (DRDF) is not primarily associated with maintaining approach angles but involves other navigational aspects. Hence, PAPI is the most directly involved system for achieving the optimal approach angle.