For safe lifting, an operator must know the position of the boom and what else?

For safe lifting, it is essential for an operator to know the weight of the object being lifted. Understanding the weight directly impacts the rigging process and the equipment used, as every crane or lifting device has a specific load capacity. If the operator is unaware of the weight, they could easily exceed that capacity, leading to catastrophic failures such as tipping, structural collapse, or equipment malfunction. Knowing the weight allows the operator to select appropriate rigging equipment, determine the correct lifting technique, and ensure that the lifting plan adheres to safety protocols.

The other options provided may be relevant in certain contexts but do not carry the same level of critical importance as knowing the object's weight. For instance, while operational history can provide insights into previous use and maintenance, it does not directly affect the immediate safety of the lift in the same way that weight does. Similarly, weather conditions and boom height may influence lifting operations but rely on the fundamental understanding of the load's weight to ensure the lifting process is safely managed.