National Commission for the Certification of Crane Operators (NCCCO) Mobile Crane Practice Exam

What hand signal must be obeyed at all times?

1. Swing

2. Clog-everything

3. Stop

4. Hoist Slow

The correct answer is: Stop

The hand signal for "Stop" is crucial as it serves as an immediate command that halts all operations to ensure the safety of the crew and the integrity of the lift. This signal is vital in potentially dangerous situations where the crane operator or the ground crew needs to pause work to avert an accident or to reassess the situation. When a "Stop" signal is given, it overrides all other signals, ensuring that all parties understand the importance of ceasing activity—whether it's a lift in motion, swinging, or any other operation involving the crane. Being able to respond promptly to this signal is essential for maintaining a safe working environment on the job site. Other signals, such as those for swing or hoist slow, while important for directing operations, do not carry the same immediate imperative as the "Stop" signal. Therefore, it is crucial that this command is followed consistently to ensure everyone's safety and support effective communication among all involved in the operation.