Underwater Escape Training Unit

The Dunker Tri service unit trains British Armed Forces aircrew and frequent flyer passengers to escape from a helicopter crash into a body of water.

The Dunker is also utilised by foreign nationals of the armed forces of countries such as Ireland, Portugal and Turkey. Other organisations such as Fire Brigades, Air Ambulances, Air Support Units, Westlands Helicopters and QinetiQ, also train their staff in the Dunker.

Originally based at HMS Vernon using actual aircraft cockpits, the Unit moved to its modern purpose built facility at RNAS Yeovilton in 1985.

Two specially constructed modules are used, one to represent the cockpit of small aircraft such as the Lynx, and another for large aircraft such as the Merlin. The large module is split into two halves; one half represents the Merlin, the other the Sea King. The observers mission console and crewman's station is fitted for the Merlin, as it in the other half for the Sea King Mk6.

After a comprehensive brief from staff trainees strap themselves into the mock cockpit, which is then rapidly immersed completely underwater. The individual must then escape using the correct procedure.

This is repeated in the dark with the module turning upside down underwater to increase the degree of realism. Divers block off windows and exits to simulate them becoming jammed due to impact, making escape more difficult so that use of a Short Term Air Supply System (STASS) is required.

All Naval Aircrew carry a STASS fitted to their jackets when flying in helicopters. The STASS is an aluminium air bottle about the size of a soft drink can fitted with a regulator to give the escapee additional breathing time underwater.

The Dunker operates Monday to Friday all year round, apart from one week every quarter when the unit goes on a diving expedition so that staff can maintain their diving currency.

The Unit has an Admiralty Mark 1 recompression chamber at its disposal in the unlikely event of problems being encountered after use of the compressed gas STASS bottles.

The UETU staff conduct research and testing of new equipment, such as a passenger version of STASS due to enter service in late 2002.