What type of separation is used in Parallel ILS approaches?

In the context of Parallel ILS (Instrument Landing System) approaches, the correct answer pertains to radar separation. During these approaches, aircraft are guided by air traffic controllers using radar to maintain safe distances between them as they approach the runway. Radar separation is essential because it allows for real-time tracking of multiple aircraft parallel to each other, facilitating their landing in a closely controlled and efficient manner.

This method of separation ensures that there is sufficient distance between aircraft that are aligned on similar or parallel flight paths, utilizing radar systems to monitor their positions and velocities. Unlike the other forms of separation, which may rely on altitude differences or time intervals, radar separation provides precise and immediate data, allowing controllers to make timely adjustments to maintain safety and efficiency during busy landing sequences.

Vertical, longitudinal, and lateral separations are relevant in other contexts but do not specifically apply to how parallel ILS approaches operate in the radar environment. Vertical separation involves different altitudes, longitudinal separation deals with time spacing along the same flight path, and lateral separation typically pertains to maintaining distance in a horizontal sense, but all these rely on different parameters than radar separation used in the context of parallel approaches.