Transcript for Infrared Radar Used in Search for Missing Family
We'll turn to the fntic search under way in central idaho for the missing plane carrying a silicon valley executive and his family. It never made its to its destination in montana. Authorities had a faint signal from the emergency beacon. And today, the search enters its fourth day. Abc's neal karlinsky has the story. Reporter: New video by search and rescue teams show how cold and rugged it is where dale smith's plane vanished sunday. Smith, seen here in home video, was by all accounts, an exceptionally experienced pilot. This morning, his family, including a daughter, who has been fighting cancer, is just clinging to hope. Our hearts are breaking. We just want our family back. Reporter: Smith was flying home from thanksgiving with his son, daughter and their significant others, headed from ohio to butte, montana, when he radioed in that he was having engine trouble near yellow pine, idaho. Emergency officials have put planes and two helicopters in the air with infrared radar, looking for signs of life in the rugged terrain. Ground teams have been searching, as well. But with temperatures below zero, it's not easy going. And relatives are scared. We don't know if they've got food. We don't know how injured they are. Reporter: The search continues this morning. But time may be running out. For "good morning america," neal karlinsky, abc news, seattle.
This transcript has been automatically generated and may not be 100% accurate.