What does the signal for "Boom Down" entail?

The signal for "Boom Down" involves one arm raised fully to indicate that the boom is being lowered. This signal is important for clear communication between the crane operator and the ground crew, ensuring safety on the job site. The full arm raised provides a clear, distinguishable cue that signifies the intention to lower the boom, allowing everyone in the vicinity to be aware of the crane's movement and act accordingly.

Using one arm raised is particularly effective as it minimizes confusion with other potential signals. It establishes a clear and direct action without introducing ambiguity. The other choices do not effectively convey the action of lowering the boom, whether through positioning or movement, which could lead to misunderstandings on a busy work site. Familiarity with proper signaling is crucial for safety and effective communication in crane operations.