When is the vent/enter/search tactic primarily employed?

The vent/enter/search tactic is primarily employed by the second arriving company because this approach is designed to enhance the efficiency of search and rescue operations in a building that is potentially engulfed in fire. The first arriving company typically focuses on establishing water supply and fire suppression. By leaving ventilation operations and entering the building to search for victims to the second company, the initial responders can more effectively manage fire control and mitigate hazards.

The second arriving company can assess the situation after the first company's efforts, making it safer to enter the structure and search for occupants. Ventilation helps improve visibility and airflow, which becomes crucial once the fire is being handled. This tactic is especially valuable when it can be executed safely and effectively following the initial response objectives.

In this context, the other options do not accurately depict the tactical approach. The first arriving company has other immediate priorities than venting and searching. A sufficient water supply might contribute to safety but does not dictate when this tactic is used. Lastly, limiting the tactic to high-rise buildings overlooks its applicability to various structures in suburban settings where multiple responding companies can coordinate their efforts.