At which point is the stage cylinder attached to the diver?

The stage cylinder is typically attached to the diver during all stages of the dive. This allows for flexible gas management throughout the dive profile. By having the stage cylinder secured, the diver can access the additional breathing gas necessary for deeper sections of the dive and ensure they have the appropriate mix for various depths.

This arrangement is crucial for safety and efficiency, particularly in more complex dive profiles where decompression stops and gas switches are involved. Keeping the stage cylinder attached during all phases also supports a smooth transition between different parts of the dive, ensuring that the diver can respond to changes in depth or other conditions without having to pause to attach or manage equipment mid-dive.

By using the stage cylinder throughout the dive, divers can manage their gas consumption effectively and be better prepared for any required decompression obligations that arise from deeper dives.