What does a signal person need to communicate to the operator for a "boom up" signal?

The correct answer is that a signal person communicates a "boom up" signal by raising both arms with palms up. This gesture is universally recognized in the industry as a clear indication that the operator should elevate the boom of the equipment. The palms facing up signal that the boom is to be lifted upward, ensuring that the operator understands the direction of the intended movement.

Using both arms raised also provides a larger, more visible signal, making it easier for the operator to see and interpret from a distance. Effective communication through clear, standardized signals is crucial for maintaining safety on job sites, especially when operating heavy machinery.

The other options do not accurately represent the standard signal for "boom up." Lowering arms or waving an arm do not convey the message of lifting, and simply pointing up with one finger is typically not recognized as a formal or clear signal for this operation. The use of both arms is essential for clarity and safety.