A crane with a maximum main boom length of 30 metres (100 feet) is equipped with a two-block warning system. The operator is lifting a 2-tonne (4,400 lb) pre-cast concrete panel. If the two-block warning alarm sounds intermittently during the lift, what immediate action should the operator take?

Question: A crane with a maximum main boom length of 30 metres (100 feet) is equipped with a two-block warning system. The operator is lifting a 2-tonne (4,400 lb) pre-cast concrete panel. If the two-block warning alarm sounds intermittently during the lift, what immediate action should the operator take?

Answer options:

• Speed up the hoisting operation to clear the obstruction quickly.
• Lower the boom slightly to increase the distance to the sheave. ✅ Stop hoisting operations and investigate the cause of the alarm.
• Retract the boom to shorten its length, then resume hoisting.

Correct answer: Stop hoisting operations and investigate the cause of the alarm.

Explanation: A two-block warning system indicates that the load block is dangerously close to the boom tip sheave, posing a risk of severe damage to the hoist rope or boom. The immediate and correct action is to stop all hoisting and booming in operations and investigate the cause of the alarm to prevent two-blocking, which can lead to rope failure or structural damage.