According to safe rappelling practices, what should be checked regarding carabiners?

In safe rappelling practices, it is crucial that carabiners are locked and not cross-loaded. A locked carabiner ensures that the gate does not accidentally open under load, which could lead to catastrophic failure during a rappelling operation. This feature is vital for maintaining the safety and integrity of the entire system.

Additionally, ensuring that carabiners are not cross-loaded means that the load is properly aligned along the spine of the carabiner. Cross-loading compromises the strength of the carabiner, as it can lead to unwanted stress on its gate or sides, potentially resulting in failure. By prioritizing these safety features, a rescuer can significantly reduce the risks associated with rappelling.

Other options presented do not address these fundamental safety concerns directly. While lightweight carabiners may seem advantageous, the strength and locking mechanism are far more critical in life-safety scenarios. Having multiple carabiners does not diminish the need for careful consideration of their locking status and alignment. Finally, while visibility can be beneficial in some contexts, it does not influence the mechanical integrity and safety critical requirements that locking and alignment provide.