What is required on a hydraulic crane to hoist personnel?

The correct response focuses on the essential requirements for safely hoisting personnel using a hydraulic crane, which typically includes having a boom length indicator. This device provides real-time information about the length of the boom in use, ensuring that operators can make informed decisions regarding load limits and stability.

The boom length is critical for determining the working radius and lifting capabilities of the crane, which is particularly important when personnel are being lifted. Maintaining awareness of the boom length helps prevent configurations that could lead to tipping or other hazardous situations. Since personnel safety is paramount, having accurate boom length information directly influences the safe operation of the crane and helps in complying with safety regulations.

In the context of the other options, while load weight indicators and emergency stop buttons are also important safety features, the boom length indicator is specifically related to the unique challenges and safety requirements associated with personnel lifting. Wind speed sensors are generally more relevant for outdoor operations and assisting in evaluating environmental conditions, but they do not directly relate to the operational control of the crane regarding personnel safety in the same way that a boom length indicator does.