CARTER COUNTY, Tenn. -

A plane headed from Charleston, South Carolina to Akron, Ohio made a stop in Elizabethton Tuesday evening, but right after takeoff something went wrong.

A small Cessna 172 crash-landed on Holston Mountain Tuesday evening, just a few miles from the Elizabethon airport.

We're told the plane needed fuel and landed in Mountain City; the pilot couldn't get fuel there, so he continued to Elizabethton.

Just a few minutes later and about five miles from the airport, the plane went down in the rugged hills of Stoney Creek. On board was the pilot Scott Miller, passenger Andrea Denning, and her 15-year-old-son, all from the Akron, Ohio area.

Carter County Sheriff Chris Mathes says it was a cell phone that may have saved the lives of three people on board. "At best the cell phone had not even a little bit of service. No one would have even known they were missing. There were no eyewitnesses, no person that heard a crash, heard anything, there was no fire," he said.

The phone call to 911 helped rescuers find their coordinates. Wings Air Rescue found the crash site from above and helped get rescue crews in, but it wasn't easy. We're told crews had to carve a path and hike their way in, taking several hours to get the three people out and to the hospital.

Now comes the investigation into what happened, a process led by the FAA and NTSB. "Based on what evidence we have, the engine was probably running at the time that it crashed. It wasn't a dead stick based on the propeller cutting out some of the trees," adds Mathes.

Investigators say they don't want to speculate on the cause, but we talked with long-time pilot, Dr. Charlton Stanley, who says flying in and around the mountains can be tricky, especially for pilots who've never done it before. "The wind, if you're not used to it, can be very treacherous. But pilots that know and understand mountain flying can use those winds to their advantage," he explained.

Investigators believe this was the pilot’s first time flying in or out of the Elizabethton airport.

We're told the two adults have been upgraded to serious condition at the hospital. The juvenile was walking around and talking to rescue crews after the crash.

Regardless of the cause, Sheriff Mathes, who has worked about five plane crashes in his over seven years as sheriff, says it's amazing the outcome ended so positively.