Why must drills remain attended at all times when in operation?

Drills must remain attended at all times during operation primarily to prevent accidents and ensure safety. When drills are in use, there are numerous potential hazards that can arise, including equipment malfunctions, unexpected material reactions, and operator fatigue. An unattended drill poses risks not only to the immediate operator but also to other personnel working nearby.

Having an operator present allows for immediate response to any issues that may arise, such as a sudden jam, overheating equipment, or the need for an emergency shutdown. Additionally, attentive operators can better monitor the drilling environment to identify hazards such as unstable ground conditions or other safety risks.

The other options, while they reflect some considerations of operational efficiency and monitoring, do not address the critical safety aspect that is paramount in mining operations. Keeping drills attended is a fundamental practice to maintain a safe working environment for all personnel involved.