Communication and Hand Signals
One voice, one signal
Effective communication prevents most crane accidents. The signal person must be qualified and positioned to see the load, the operator, and the path. Use a dedicated radio channel or standardized hand signals, and agree on signals in the pre-lift meeting. Hand signals include hoist (forearm vertical, forefinger up, small circle), lower (arm down, forefinger down, small circle), boom up or down (thumb up or down), swing (point in the direction of swing), stop (palm down, arm swept horizontally), and emergency stop (both arms extended, palms down, swept). "Dog everything" means hold all functions. Anyone may give an emergency stop signal.
Traps
Questions test who may signal: only the designated signal person, except that anyone may give an emergency stop. Multiple signal persons create confusion unless the plan assigns one. Radio failure means stop. Hand signals must not be "interpreted"; if unclear, stop. Taglines control rotation but are not communication devices. For blind lifts, use a signal person with continuous visibility or a relay.
Rule of thumb
If you cannot see the load, the signal person, or the landing zone, stop until communication is restored.