Crossed Commands on a Shared Channel
You are the signal person for Crane 2, a 60-ton crawler crane placing a 12,000-pound steel beam. Crane 1, a 50-ton crawler, is pouring concrete from a bucket 70 feet away. Both operators are on radio channel 6 because the site superintendent said one channel keeps everyone informed. You hear the other signal person transmit “boom up.” Your operator immediately begins booming up, and your beam starts drifting toward the ironworkers on the steel deck. You are 80 feet from the operator and have a clear view of the load. The radio in your hand is working, but two other crews are also talking on channel 6. The ironworkers are not yet tied off. The operator cannot see the drift because the beam is on his blind side.
1. What immediate action do you take when your operator begins booming up on the other crew's command?
Read the worked answer
Immediately key the radio and say: “All stop, all stop, Crane 2 stop.” Give the stop hand signal as a backup if the operator can see you. The operator must stop hoisting and swinging, hold the load, and not resume until you confirm. Do not try to correct the movement with another command while the load is drifting; stop first. Then check the beam's position, the ironworkers, and the rigging. The root cause is cross-talk: your operator acted on a command addressed to another crane. Resume only after a clear channel and a positive confirmation.
2. What radio protocol should have been established in the pre-lift meeting? Include how each transmission should be worded.
Read the worked answer
Pre-lift: assign a dedicated channel per crane, or a clear protocol if a shared channel is unavoidable; test the radio; identify the crane, operator, and signal person at the start of each transmission. Example: “Crane 2, this is signal person Jones, boom up slowly.” The operator repeats the command or acknowledges. Use “stop” only for the crane addressed, and use “all stop” for a site-wide emergency. No casual talk on the channel. Establish hand signals as backup and confirm line of sight. The pre-lift meeting should include both operators and both signal persons.
3. The other signal person gives a stop signal for his own crane, but your operator hears it and stops. Is that wrong? What should happen next?
Read the worked answer
No, the operator is not wrong to stop. A stop signal should be honored first and questioned afterward. The operator should hold the load and wait for clarification on the dedicated channel. The other signal person should confirm whether the stop was meant for Crane 1. If the shared channel remains, use crane identifiers and repeat-backs. If cross-talk cannot be eliminated, stop one crane until channels are separated. This is a communication control issue, not an operator discipline issue.