Navy joins search for helicopter wreckage

The Hughes 500 helicopter is believed to have crashed on the northern side Lake Sumner. Photo / Wikimedia Commons image posted by user Craig Allen

A remote-operated navy submersible will begin searching for the wreckage of a helicopter, thought to be in a deep north Canterbury lake, today.

Michael Graeme Mehrtens, 35, was the only occupant of the Hughes 500 helicopter which is believed to have crashed near Breaksea Bay in Lake Sumner on Monday afternoon.

Police said the helicopter was thought to be so deep it was out of the reach of dive teams.

Searchers earlier this week called on the navy to provide equipment and expertise to aid the recovery operation.

The remote-operated vehicle arrived at the lake yesterday and it was expected it would start searching for the wreckage today, Inspector Craig McKay said.

The helicopter was believed to be located offshore from Breaksea Bay on the northern side of the lake, at a depth of about 125 metres.

It was not known how long it would take to locate the helicopter, or even if it would be located, Mr McKay said.

"There are so many variables in this operation. We are working in very deep water, and while we are reasonably confident we know the approximate location of the aircraft, there are no guarantees."

If the helicopter was located searchers planned to use the remote-operated vehicle's manipulator arm to attach a line and with airbags manoeuvre the helicopter into shallower water, where divers can retrieve it.