A team of KyANG combat controllers deployed to Lake Winnepesaukee, N.H., to conduct cold weather training that included their first exposure to ice diving, as well as avalanche and mountain survival training.

"We train for all climates," said Master Sgt. Bob VanAssen, a combat control specialist with the unit. "Someday we might have to retrieve an aircrew or sensitive pieces of equipment from a frozen body of water."

Many of the techniques that divers use in frozen conditions are similar to those they employ in warm water, but there are a few major exceptions.

First, ice divers must cut a hole in the frozen sheet covering the lake or ocean in order to gain access to the water.

In this case, the ice covering Lake Winnepesaukee was two feet thick, requiring access holes to be cut with a large chain saw.

Once underwater, the divers had only that small opening through which to exit. Everything else was a ceiling of solid ice, which meant the divers could not surface whenever they wished, VanAssen said.

They also were required to keep track of the entry hole in order to return safely.

"Once submerged under the ice sheet, there’s no natural or man-made references to assist in pinpointing your location relative to the entry hole," said Senior Airman Sean McLane of the 123rd STF. "We may swim away from the hole on a search, and there’s a risk of getting lost."

To prevent that, each diver used nylon tether lines secured to the surface and manned by a teammate who was "topside."

However, team members reported that once through the ice, the rest of the dive was relatively standard.

Another danger of ice diving is that moisture from a diver’s breath can freeze his scuba regulator, cutting off the air supply. The water temperature during the training hovered at 33 degrees, giving little margin for error.

The STF divers also had to take precautions to maintain their body temperatures. Rubber dry suits with tight-fitting seals around the neck and wrists were used to keep the divers’ core body temperatures at normal levels. Also, most team members were bundled in several layers of thermal underwear beneath their suits.

Senior Airman Joe Youdell uses a chain saw to cut a hole in the ice.

"Although the suits are built to withstand the abuse of our training, you’ve got to be very aware that you don’t come in contact with sharp objects, such as jagged ice fragments, otherwise flooding or a slow leak could make for a very uncomfortable time in the water, said Maj. Jeremy Shoop, the unit’s commander.

"A good general rule of thumb is to don the suit without all our scuba gear first, then ‘dip-test’ it by getting into the water to test for leaks before we dive."

With the air temperature below freezing and a constant stiff breeze blowing across the lake’s surface, the threat of hypothermia was present above the ice, as well as below.

The effects can be life-threatening.

"This training is valuable, (but) you’ve got to pay attention," said Tech Sgt. Tom DeSchane, another combat controller in the 123rd. "The colder it gets, the more the penalty for stupidity increases."