HUET stands for Helicopter Underwater Escape Training: training to escape from a submerged helicopter. Aircrew and regular passengers practise immediate self-rescue from a cabin whose attitude and visibility can change. At Yeovilton, the Royal Navy brought this training component together with Maritime SERE and sea-survival preparation. Within that combination, HUET covers escape from the cabin underwater, followed by survival at the surface and recovery from the water.
Escape with a changed cabin attitude and poor visibility
When the training cabin rotates, its seat and escape exits rotate together. Their arrangement within the cabin remains the same; what changes is the body's attitude in relation to the water surface and the usual visual frame of reference. Darkness also removes the option of simply looking at the seat, fastenings and openings. Underwater training therefore includes rehearsed procedures and orientation by touch. Trainees need to find the cabin features under these conditions and apply the escape procedure they have been taught. The British Underwater Escape Training Unit also trains with blocked exits: trainees must then find another usable exit instead of the familiar opening.
From classroom instruction to the submerged cabin
The British basic HUET course starts with the reasons for the training, exit procedures and the hazards associated with leaving the cabin. Four runs in the HUET module follow:
- submerged in daylight,
- submerged and inverted in daylight,
- submerged and inverted in twilight,
- submerged and inverted in darkness.
For the final three runs, the cabin remains inverted while visibility is reduced from daylight through twilight to darkness. The four runs belong to this particular course at Yeovilton. The training unit there also uses cockpit representations for small and large aircraft, together with STASS, the Short Term Air Supply System, for additional breathing time underwater.
The connection to Maritime SERE
The Royal Navy brought underwater escape, personal life rafts and winch recovery together in a combined Maritime SERE and underwater escape facility. Previously, these training elements had been separated by location and time. The combined sequence moved from the submerged cabin to the trainee's own life raft and finally to recovery from the water. Wind, rain, waves and darkness could be reproduced in the environmental pool. This allowed the transition to a sea-survival situation to be practised under difficult conditions. Winch recovery formed a separate training element. In an actual recovery, an operational aircraft must be able to reach the person. Raft work and recovery are additional tasks after the HUET escape, rather than components of every basic HUET course.
What the training devices change
A Helo Dunker is the cabin representation used for underwater exercises. In the US Navy, one such multi-place system is called METS, the Modular Egress Training Simulator. It can be configured for an aircraft type and replicates its escape exits. For trainees, this affects the openings they can actually reach and their arrangement in relation to the seat. HUET names the training; METS names a device on which its practical exercises can take place.
The US Marine Corps uses devices including the SWET, Shallow Water Egress Trainer, and the MAET, Modular Amphibious Egress Trainer, within its underwater-egress programme. The SWET is an individual training seat for familiarisation with submersion and supplemental emergency breathing devices. It is used before or alongside the larger trainers. The MAET adds a cabin with escape exits and rotation through to a fully inverted position. The training task therefore develops from the limited space of a single seat to orientation and escape within a larger cabin representation.
An Australian training context
Australian Army HUET training at Robertson Barracks used six escape runs, the last three with blindfolds. Trainees had to rely on touch, rehearsed procedures and controlled breathing. Compared with the British four-run course, loss of sight was created here by blindfolds. Sea-survival training followed, covering life rafts and the use of survival equipment after leaving an aircraft or vessel.