NSW Deputy Coal Mine Practice Exam

In underground mine ventilation, air moves from the intake network toward the working faces and then returns back toward the surface. A Return Airway is the portion of the intake that has become part of the path carrying air back, i.e., it lies on the return side. The boundary used is within 100 metres outbye of the most inbye completed crosscuts (C/Ts). This definition captures which sections are already part of the returning flow rather than supplying fresh air, which matters for monitoring gas levels, controlling airflow, and safety procedures. The other options describe a source of fresh air (the main intake shaft), a system function (ventilation network control), or air inside a safety refuge chamber, none of which define the pathway that carries used air back to the surface.