What is the purpose of the Standard Terminal Arrival (STAR) procedure?

The Standard Terminal Arrival (STAR) procedure serves a vital role in streamlining the transition of aircraft from the en route phase of flight to the approach phase. By providing a predefined route, STARs help ensure that planes arrive at the airport efficiently and safely. This standardization aids air traffic controllers in managing air traffic flow and minimizes the risk of congestion in busy airspaces.

As aircraft are descending and preparing to land, a STAR incorporates various waypoints and altitudes that guide pilots and help maintain safe separation from other traffic. This procedure also allows for better fuel management and minimizes the need for last-minute changes to approach routes, contributing to overall safety and efficiency in the terminal airspace.

In contrast, the other options describe different operational aspects of aviation that do not align with the specific purpose of a STAR. Although option A refers to departure routes, it doesn't pertain to the arrival management provided by STARs. Option B, while indicating a focus on airport arrivals, doesn't detail the structured transition from en route to approach. Lastly, option D discusses air traffic control protocols but misses the crux of the STAR's function, which is about facilitating the specific route for arrivals rather than just outlining procedural protocols.