Radio Failure During a Blind Precast Panel Set
A 14,000 lb precast wall panel is being set into a below-grade vault. The crane operator can see the boom tip but not the landing zone, which is behind a 10 ft retaining wall. The designated signalperson is on the far side with a two-way radio. Ten minutes into the lift, the radio crackles and goes dead. A laborer standing near the operator begins giving hand signals, while a second worker on the far side waves his arms. The operator hears someone shout 'come down' but cannot tell who said it. The panel is suspended 6 ft above the vault floor, and two workers are guiding it by hand. The operator's view of the laborers is partly blocked by the wall, and the load is drifting slightly in the wind.
1. What should the operator do immediately when the radio fails?
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The operator should stop all crane motion and hold the load, then assess whether a safe controlled lowering is possible using a prearranged emergency signal from the designated signalperson. The operator should not respond to the laborer's improvised hand signals or to the shouted 'come down' because the source and meaning are unclear. Multiple people are signaling, and the operator cannot see the landing zone.
The crew should clear personnel from under the suspended panel and stop the workers from guiding it by hand. If the load is drifting, the operator should not chase it with the crane. The immediate priority is to stop, secure the area, and restore one clear line of communication. Moving the load on ambiguous signals is how a blind lift turns into a serious incident.
2. Who may direct the lift, and what signal rules apply?
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Only one designated, qualified signalperson should direct the lift. The operator should obey that person's signals and should stop for an emergency signal from anyone. The laborer near the operator and the second worker on the far side are not authorized to take over by waving or shouting. Hand signals are acceptable only if the operator and signalperson can see each other clearly and both know the agreed signals. A radio is a supplement, not a substitute for a clear signal plan.
If the designated signalperson cannot see the landing zone or cannot be seen by the operator, a relay or a different signal position is needed. The operator should not act on a signal that is not understood. The load should remain stopped until one signal source is established and confirmed.
3. How should the lift resume safely?
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The crew should replace or repair the radio, establish a backup communication method, and confirm that the designated signalperson has a clear view of the landing zone and the operator. A pre-lift meeting should confirm the hand signals, radio channel, emergency stop signal, and who is in charge. The area under the panel should be cleared, tag lines should be rigged, and the workers should not guide the panel by hand while it is suspended.
Before resuming, the operator should test the communication and raise the panel slightly to confirm control. If reliable communication cannot be restored, the lift should not continue. The panel should be landed in a safe location if possible, and the set should be rescheduled with a signal plan that covers the blind zone.