Slewing Past a Blind Corner with Radio Failure
You are lifting pallets of blockwork from the ground to the third floor of a building under construction. The landing point is behind the building line and is not visible from the cab. The rigger/slinger is on the third floor with a radio, and a second banksman is at ground level in sight of the cab. The agreed signal system is radio with hand signals as fallback. Mid-lift, the radio goes silent - you hear nothing, not even static. The load is a 900 kg pallet on a four-leg sling, currently at 30 m radius over the site compound, with no one beneath. The ground banksman is visible and has not signalled. The third-floor rigger is out of sight behind the slab edge.
1. What is the correct immediate action and what signal discipline applies?
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Stop the crane. With radio contact lost and the landing point not visible, you no longer have a reliable signal from the person controlling the landing, so continuing is unsafe. Hold the load stationary over the clear compound, or lower it slowly to a pre-agreed safe landing area if one is designated and clear - do not slew toward the blind landing point. The fallback hand-signal system only works if the signaller is in clear sight of the cab, which the third-floor rigger is not. The ground banksman can relay only if a pre-agreed relay procedure exists and the banksman can see both the load and the landing point; if not, the lift is suspended. Establish communication - replace the radio battery or use a spare - before resuming.
2. How should the signal system be set up so this does not recur?
Read the worked answer
Before the lift, agree a single designated signaller for the landing point, confirm radio channel and a test call, and agree a lost-communication protocol: stop, hold or lower to a designated safe area, and do not resume until voice contact is restored. Where the landing point is blind from the cab, either use a signaller in sight of the cab who is in direct contact with the landing rigger (relay), or use a camera or mirror arrangement, or reposition the crane. The fallback hand signals must be given by someone the operator can actually see. Brief all parties and record the arrangement in the lift plan.