Waage Drill II diving accident

The Waage Drill II diving accident occurred in the North Sea off Scotland on 9 September 1975, when two divers died of heatstroke after the chamber they were in was inadvertently pressurised with helium gas.

Because of the cross-referencing capabilities of the system, it became the practice of the shift supervisor to set the valves of this gauge to read the internal depth of the bell prior to the divers leaving bottom, then track their ascent through the lock‑on and transfer procedure.

After Holmes and Baldwin equalized the bell with the rest of the complex, they opened the inside door and were in the process of transferring into the entrance lock when the gas leak suddenly returned.

With the needle on the Heise gauge dropping, an attempt was made to isolate the divers from the leak by sealing the door of the entrance lock that led to the bell, but according to the dive log this effort was "abandoned.

It was later pointed out by the presiding judge at the fatal accident inquiry that the way in which the diving system was designed and labelled, "especially as operated by Oceaneering, carried a high risk of human error, particularly during the distractions of an emergency".