An SA Air Force helicopter plunged into a dam near Bergville in the northern Berg area on Tuesday with three men aboard.

The three, who were stationed at 17 Squadron, Air Force Base Zwartkops, are believed to have drowned when their helicopter, an Agusta A109, crashed into Woodstock Dam.

They were flying in formation with two other helicopters en route to Dragon Peaks Park for a week-long training exercise.

Authorities said the cause of the accident, which happened just before noon, was unknown. It is understood that shortly before the crash, smoke was seen pouring from the tail rotor area.

The helicopter was believed to have been flying at speed when it crashed, with the pilot, co-pilot and flight engineer trapped inside.

The crash is believed to have occurred in a deep section of the dam, with neither police nor defence force divers having located the bodies by sunset when the search was called off for the night.

The search operation, led by the Durban Search and Rescue Unit, began two hours after the crash and involved 14 specialist divers from the police and navy.

According to a member of 17 Squadron, who asked not to be named, the three helicopters were on their way to Dragon Peaks to take part in a training exercise.

"Everyone is extremely shaken. The accident happened really quickly. The details are still very sketchy and those who were en route with the helicopter that crashed are still being debriefed," he said.

A diver said it was a race against time to find the bodies and added that it was impossible for anyone to have survived the crash.

"We are going all out to recover the bodies, but what is making it difficult is the size of the search area, which is between 200 and 300 square metres; the extremely cold water temperatures; the zero visibility; and the depth at which we are having to search," he said.

So far only small pieces of debris had been recovered.

Ladysmith police spokesperson Captain Charmaine Struwig confirmed that reports had indicated that just before the crash, smoke was seen coming from the helicopter's tail rotor *1.

• This article was originally published on page 1 of The Mercury on May 13, 2009