What control measure is observed during zone recon?

In the context of zone reconnaissance, the correct control measure is that phase lines are reported. This is essential for maintaining situational awareness and ensuring coordination among elements conducting the reconnaissance. Phase lines serve as reference points along the route that teams can report their positions and findings. This reporting helps maintain a clear understanding of progress and findings, enabling commanders to effectively analyze the information and make informed decisions about subsequent operations.

Zone reconnaissance involves a systematic approach to gather intelligence about a designated area, and clear communication through established phase lines is crucial to achieving the objectives of the mission. By reporting at these defined locations, the reconnaissance teams can provide timely updates on enemy presence, terrain features, and other important aspects of the zone.

The other options reflect misunderstandings of effective reconnaissance practices. Flexible and loosely defined boundaries could lead to confusion and a lack of clarity in operations. Rapid advancement without communication compromises safety and increases the risk of disorganization. Finally, operating independently without oversight can result in a lack of cohesion and failure to share critical information that could impact the larger operation. These factors underscore the importance of structured control measures, such as phase lines, during zone reconnaissance missions.