Buoyancy Wing Comes Loose During Dive

A diver’s back-plate comes loose, partially releasing his wing

Reported Incident

A very experienced technical diver got distracted and mounted the wing (BCD) on his double cylinders incorrectly (backwards). Already wearing a dry suit at a temperature of 30°C (86°F), he realized his mistake and quickly remounted his equipment. The shipwreck lies 55 msw (180 fsw) deep in a place known for a strong current. The diver in question was the last of five divers descending. When he reached the bottom we noticed a large volume on the right side of his double tanks. To our surprise the volume was the lower part of his wing (BCD).

The back plate and wing are connected by two screws and the bottom screw had come loose, allowing the output of the wing and movement side-to-side of his double cylinders. Immediately, we canceled the dive and began to surface. We warned the diver of the situation and told him to keep his head up during the ascent to prevent the double cylinders deviating laterally. At the surface, the diver had trouble keeping afloat because the wing being in that position was not helping. Aided by the group at the surface, the diver left the water unharmed.


In technical diving it is common to “sandwich” an inflatable wing between a steel or aluminum back-plate and two dive tanks banded together, (known as a set of doubles). Steel wing-nuts are often used and, unless tightened with a wrench, it is not uncommon for them to sometimes loosen. They do not usually completely undo however and this diver must have been surprised when at significant depth his wing came loose.

A quick reaction and clear communication from his dive buddies ensured the diver surfaced safely. This incident serves to remind all divers wearing double tanks to tweak-down their wing-nuts when attaching a back-plate and wing.

Peter Buzzacott, MPH, Ph.D.