Rescuers Battling Near-Subzero Temperatures in Search for Missing Plane, Survivors

Dec. 5, 2013— -- The search for a missing airplane and the five people onboard has entered its fifth day as rescuers scoured the snow-covered Idaho backcountry looking for signs of life.

New video taken by search and rescue teams shows the cold, rugged terrain where Silicon Valley executive Dale Smith's plane vanished from radar last Sunday.

Onboard the six-seater Beech Bonanza Dale Smith was piloting were his son, Daniel Smith and his wife, Sheree Smith; his daughter, Amber Smith, and her fiancé, Jonathon Norton.

Five airplanes and two helicopters equipped with infrared radar are leading the charge as rescuers look for survivors in the sub-zero temperatures.

Alan Dayton, an uncle of the family, said his biggest worry was how the five are surviving the elements. The high temperature forecast in Valley, Idaho, today was 16 degrees.

"We don't know if they've got food. We don't know how injured they are," Dayton said.

The group was headed from Oregon to Butte, Mont., last Sunday when Smith radioed he was having engine trouble near Yellow Pine, Idaho.

Authorities said the early-1980s model plane lost contact with the cell tower near a remote airstrip where he had hoped to make an emergency landing.

A weak emergency transmitter signal was picked up by a search and rescue plane one mile from the airstrip on Tuesday, providing rescuers with a glimmer of hope.

Crystal Smith-Christensen, one of Smith's daughters, told ABC News she is battling cancer and just wants her family back by her side.

"Our hearts are breaking," she said. "We just want our family back."