What should be used if the signaler is not in clear view of the crane operator?

The correct choice emphasizes that when the signaler is not in clear view of the crane operator, relying solely on hand signals can lead to miscommunication and potential safety hazards. In such situations, it is critical to use a different form of communication that ensures both the operator and the signaler can effectively convey and understand instructions. This could include using voice communication systems, such as two-way radios, which provide clearer, more reliable interactions compared to visual signals that may not be seen due to obstructions.

Using alternative forms of communication can enhance safety and efficiency because they can maintain constant contact, allow for immediate clarification if misunderstandings occur, and are less dependent on line-of-sight visibility. While visual communication tools might work in some scenarios, they are not suitable when the signaler is obscured from the operator's view. Similarly, options like radio communication alone or written instructions may not fully address the dynamics of an active worksite where immediate and interactive communication is necessary.