Every year in the UK about 100 cases of decompression illness requiring recompression occur. Some result from predisposing medical conditions, others from poor technique. However, there is evidence that others are caused by malfunction of equipment designed to prevent DCIs.
Many sport divers now employ a decompression computer. Not too long ago one popular model was withdrawn because of unreliable operation. But I have seen three cases in which the owners stories suggest that other makes of computer have malfunctioned.
In each case, the divers suffered DCI after dives within what according to their computers were safe profiles.
None of them had any of the recognised physical predispositions for DCI. Each did a dive requiring long deco stops according to their tables (which were checked later), but their computers permitted them to go directly to the surface, or required only a brief stop.
One divers tested his computer in a hyperbaric chamber against seven identical models with a dive-profile similar to that on which he had suffered DCI. It indicated that it was safe to surface when all the others required eight or nine minutes of stops.
When the other two divers had their computers chamber-tested they were found to require considerably fewer stops than those against which they were tested. Two divers sent their computers back to the relevant manufacturers, both of which replied saying that no fault had been found, but that the computers had accidentally been broken during testing! The divers were sent new replacements.
We live in a technological age, but scepticism about the infallibility of some computers might well be healthy.