Efforts to find a Twin Otter aircraft missing in Antarctica with three Canadians aboard remain on hold because of poor weather, a rescue official in New Zealand told CBC News this afternoon.

The missing Twin Otter, operated by Calgary-based Kenn Borek Air, had been transmitting an emergency beacon signal since late Wednesday night, local time, but it now appears the battery has died.

New Zealand's Rescue Co-ordination Centre, which is handling the search, said rescuers circled over the site of the signal Friday morning, near the northern end of the Queen Alexandra Range, but heavy cloud cover and winds prevented rescuers from making visual contact.

“When conditions ease, the intention is to set up a forward base at a location approximately 50 kilometres from the beacon site, from which to launch operations to the site," said rescue mission co-ordinator Kevin Banaghan.

Steve Rendle, another official with the Rescue Co-ordination Centre, says skies are expected to clear Saturday morning local time, which should allow rescue teams to fly over the area.

The Canadian pilot of the missing Twin Otter was identified by his wife as Bob Heath of Inuvik, N.W.T. The Canadian pilot of the missing Twin Otter was identified by his wife as Bob Heath of Inuvik, N.W.T. (Courtesy Lucy Heath)

The Canadian's plane is grounded roughly halfway between the South Pole and McMurdo Station, a U.S. research facility in Antarctica where two helicopters, equipped with mountain survival gear, remain on standby pending a change in the weather.

“Weather conditions remain very challenging and are forecast to continue for the next 12 hours," Banaghan said. "However, over the next 24 hours, winds in the area are forecast to drop from 170 km/hr to 35 km/hr, with cloud forecast to lift and become scattered."

The pilot of the missing aircraft has been identified by his wife, Lucy, as Bob Heath from Inuvik, N.W.T.

Mark Cary, a former pilot with the airline, said he flew with Heath on a number of occasions and described him as an experienced aviator who was well versed in cold-weather survival techniques.

"I’m very, very confident that if this crew indeed survived getting the aircraft on the ground that Bob is the kind of individual that would be able to survive until rescuers could get to him and his location," he said.

Kenn Borek Air, is yet to confirm the names of those aboard the aircraft.

Jim Pearce, a retired pilot with the company who flew with Heath described him as "probably one of the most experienced Antarctic pilots in the world today. It's a very very challenging place to work, and a very very challenging place to fly."

He said that Kenn Borek Air would have provided the three Canadians with the best survival gear available.

"They'd have extreme cold weather gear available, and the most up-to-date survival packs," he said

The missing plane had been flying from the South Pole to an Italian base in Antarctica's Terra Nova Bay. A spokesman for the U.S. National Science Foundation has said the flight was in support of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development.

No signal from beacon

Earlier rescue efforts were thwarted by the poor weather. A DC-3 spent about six hours circling the area, hoping to make visual contact and drop a satellite phone to the missing crew.

However, poor visibility and high winds forced the DC-3 to return to McMurdo Station, a U.S. research facility. Weather conditions were said to include solid cloud, heavy snow and winds up to 170 km/h.

Michael Flyger, a spokesman with New Zealand rescue centre said earlier Thursday that in addition to the long distances and the terrible weather conditions rescuers must face, the search effort will confront the issue of altitude.

When the rescue beacon was transmitting, it was coming from a location about 4,000 metres above sea level, Flyger said.

"With that comes problems around oxygen, comes problems around wind chill and temperatures," he said.

"Certainly, it's not an easy place to get into, but we've got some pretty good people who are absolutely itching to get in there and help to assist."

With files from The Canadian Press