Which types of tracks cannot be manually correlated?

The correct answer is that different environments of tracks with active environment conflict cannot be manually correlated. This is because tracks in different operational environments may have distinct data formats, protocols, or operational parameters that prevent effective correlation. When tracks experience active conflicts, such as differing altitude layers, sensor types, or geographic information systems, it complicates the ability to merge or correlate them manually. Each environment may dictate unique operational considerations, making it impossible to reconcile tracks accurately when they originate from conflicting sources.

In contrast, local and remote tracks, as well as two remote tracks, can often be correlated based on available common data or protocols, such as standard communication formats. Simulated to live tracks also have mechanisms to aid correlation; although some discrepancies may exist between simulation and real-world data, technology facilitates a level of matching. Thus, the complexity of varying operational environments under active conflict is why manual correlation in that case is not feasible.