A Jet Ranger helicopter was used to fly over a southern portion of the Big South Fork National River & Recreation Area on Sunday to locate two missing hikers.

A Knoxville couple are recovering after spending a night in the backcountry of the Big South Fork National River & Recreation Area amid single-digit temperatures Saturday night.

The Tennessee Highway Patrol said Friday that its aviation team was able to assist in the location and rescue of the missing hikers Sunday afternoon, after they became lost while hiking in the Sheep Ranch section of the Big South Fork.

The couple, whose names have not been released, were reportedly from the Knoxville area. The woman was transported to an area hospital with non-life threatening injuries, including frostbite. Her husband, however, was airlifted from the Elgin helipad to University of Tennessee Medical Center in Knoxville, where he was listed in serious condition.

According to a news release by THP, a search for the missing couple began around 7 a.m. Sunday, when the woman telephoned their daughter to say that they were attempting to find their way out of the woods.

The woman had made contact with her daughter the previous evening telling her they were lost and unable to find their vehicle. Saturday night was cold, with snow on the ground. According to data preserved by the National Weather Service, the temperature dipped to four degrees in Oneida Saturday night, and reached only 19 degrees on Sunday.

Once she was contacted the second time, the couple's daughter phoned authorities, and a search was launched, involving the Scott County Sheriff's Department, Scott County Rescue Squad and volunteer firefighters, in addition to park rangers from the Big South Fork.

The National Park Service requested air support from THP, due to the cold temperatures and rugged terrain along the Clear Fork River. According to THP, Lt. Brad Lund and Trooper Ryan Quinn flew a Jet Ranger helicopter into the search area, using forward-looking infrared camera technology to locate the woman and the couple's dog after about 90 minutes of searching. The woman appeared disoriented and had trouble moving, THP said.

Lund and Quinn were able to guide ground searchers to the woman's location. She had difficulty communicating with them, but told them that she had become separated from her husband, and that he was "lying on the ground somewhere not doing well."

The aerial search continued, with THP eventually finding him lying down and guiding ground searchers to his location.

THP used infrared camera technology to locate a missing hiker shortly after 3 p.m. Sunday afternoon. He was found lying on the ground and disoriented, and was transported by air to UT Medical Center in Knoxville, where he was listed in serious condition.