What is required to be located on the outside of the operator's cab?

The correct answer highlights the importance of safety and communication in hoisting operations. A legible chart depicting signals is required to be located on the outside of the operator's cab to ensure that all personnel involved in the operation can clearly see and understand the signals being used. These signals are crucial for coordinating actions between the operator and ground crew, minimizing the risk of accidents or misunderstandings during the lifting process.

Having this chart visible outside the cab serves several functions: it reinforces clear communication, allows for immediate reference, and can be easily checked by anyone involved in the operation. This practice aligns with safety protocols, ensuring that all parties are aware of the hand signals that correspond with specific actions, thus enhancing the overall safety of the hoisting operation.

While the other options may contribute to the functionality or safety of the equipment, they do not specifically address the critical need for maintaining clear communication through standardized signals, which is vital in preventing accidents on job sites.