Communication, Signals and Personnel Coordination
One voice, one signal
Effective crane communication depends on a single designated signal person. Multiple people giving signals is a classic cause of incidents and a common exam trap. The operator takes signals from the nominated rigger only, except for an emergency stop, which anyone may give. Signals must be agreed before the lift and understood by all. Standard hand signals, whistle, radio or light signals are used; radio is preferred where line of sight is obstructed, but radio failure must have a defined fallback.
Radio discipline
Use clear, standard phrases, identify yourself, confirm instructions and read back critical commands. Keep the channel free of chatter. If communication is lost, the operator stops and holds the load safely until contact is restored. The trap is continuing a blind lift on assumed signals.
Coordination of personnel
The rigger controls the load with taglines, keeps clear of the slew path and never stands under the load. The dogger or signal person positions where the operator can see them and the load. Spotters manage the exclusion zone. Everyone must know their role, the lift plan and the emergency stop signal.
Worked rule of thumb
If you cannot see the signal person and have no radio contact, do not move the load. Stop, hold, and re-establish communication. A blind lift without agreed signals is never acceptable.