What is an approach clearance?

An approach clearance is indeed the authorization given to an aircraft to execute an instrument approach. This clearance is crucial because it provides the pilots with the necessary information to descend and navigate safely to the runway, particularly in conditions where visual references may be limited, such as poor weather or nighttime operations. The approach clearance outlines the intended approach type, the specific runway, and any necessary instructions or vectors that the aircraft must follow during the approach phase.

This process is a part of the larger air traffic control system designed to ensure a safe and orderly flow of air traffic, especially during the critical phases of landing and approach. The other options do not accurately define what an approach clearance entails, as they relate to different stages of flight operations, such as landing permissions, taxi instructions, and takeoff authorizations.