When is an aircraft considered to be in Coast Status?

An aircraft is considered to be in Coast Status when it is not tracked by the computer. This indicates that the radar or tracking systems have temporarily lost the capability to monitor the aircraft's position and trajectory. In situations where coast status is declared, controllers may have to rely on the last known position of the aircraft until it comes back into radar coverage. This is critical because the absence of tracking can impact the ability to provide timely and safe separation from other air traffic.

The other choices involve situations where an aircraft is still within defined parameters for tracking or operations. For instance, descending, in holding, or on final approach all imply that the aircraft is still actively being monitored and positioned within flight trajectories by air traffic control systems.