Severe winds and heavy snow continued to hamper the search for three Canadians aboard an airplane missing in Antarctica as rescue crews on standby braced for hours of more bad weather.
No information was available on the fate of the three men aboard the ski-equipped Twin Otter, which is owned by Calgary-based Kenn Borek Air.
While the plane's emergency locator beacon emitted signals, rescue crews were unable to establish any radio contact with the trio on board the aircraft.
"Weather is hampering things at the moment," said Steve Rendle, a spokesman with New Zealand's Rescue Co-ordination Centre in Wellington, which was organizing the search.
"The winds are extreme, we are told the snow conditions are getting heavier and that's preventing the helicopters and the Twin Otter (search) aircraft from heading down."
The locator beacon, however, stopped transmitting at about 4:15 a.m. EDT, but centre spokesman Michael Flyger stressed there was no cause for alarm.
"It just means that the beacon's battery has given up. They're only designed to broadcast for 24 hours (but) in cold conditions, they don't seem to last quite that long."
Flyger said the plane's location has been pinpointed, so the loss of the locator beacon signal is not an issue.
"It's not going to compromise the search in any way because everybody knows where they'll be looking."
Kenn Borek Air, which is experienced in Antarctic aviation, did not provide any details on the three crew members on board the missing twin-engine propeller aircraft.
A spokesman for the U.S. National Science Foundation -- which operates an Antarctic research station helping in the search -- said the trio aboard the plane was thought to be a pilot, a co-pilot and a flight engineer.
"My understanding is that it was just the flight crew and no passengers," said Peter West, who is based in Arlington, Va., and had been in touch with crews in Antarctica.
The plane was flying from the South Pole to an Italian base in Antarctica's Terra Nova Bay when its emergency beacon went off en route.
The region is in New Zealand's area of responsibility and that country's rescue crews were working with U.S., Canadian and Italian authorities.
The missing airplane began transmitting signals from its emergency locator beacon early Wednesday.
A U.S. LC-130 aircraft was soon sent to the area where the signal was coming from but was unable to spot the missing plane due to heavy, low cloud.
Later on Wednesday, about 16 hours after the plane went missing, a DC-3 aircraft spent hours over the same site, hoping to catch a glimpse of the downed plane or the crew, but thick clouds again prevented a search of the terrain below.
The Rescue Co-ordination Centre said there is solid cloud cover in the area, high winds of up to 170 kilometres an hour and heavy snow.