SAVANNAH, Ga. (AP) - With four medical clinics across the Southeast, commuting by private plane was a routine day at work for Dr. Steven Roth and his surgical staff.

The Augusta-based vascular surgeon would fly at least one day a week to of the practice's satellite clinics in Atlanta, Nashville, Tenn., and Raleigh, N.C., where he and a small team of nurses and technicians would perform surgeries and consult with patients.

Now, federal investigators are working to determine why Roth's trip Wednesday night turned deadly. The private jet had returned to eastern Georgia after a day's work at the Nashville clinic 400 miles away when the pilots aborted their landing, struck a 60-foot utility pole about a quarter-mile past the runway and crashed, breaking into fragments of flaming wreckage. Roth and four members of his staff were killed, and two pilots were hospitalized.

"It's a trip that's been made hundreds of times," said Melissa Benak, the wife of Roth's Atlanta-based co-worker Dr. Mark Benak. "So I think that's why people are especially in shock."

The crash devastated the partner physicians and staff that worked closely with the 48-year-old Roth to expand the medical practice, which they called the Vein Guys, since the surgeon opened his first clinic in Augusta in 2004.

Four members of Roth's traveling medical team also died in the crash. They included nurse anesthetist Lisa Volpitto, 46; ultrasound technician Tiffany Porter, 28; and Kim Davidson, 46, who was Roth's executive assistant.

The fifth crash victim had still not been positively identified, McDuffie County Coroner Foster Wiley said Friday. A spokeswoman for the Vein Guys, Tina Vidal-Smith, said the fifth person traveling with Roth was ultrasound technician Heidi McCorkle, 28. The medical firm said in a statement that the two pilots survived.

Vidal-Smith said three of the staff had been with Roth for at least five years. Only Porte r, a native of Albany, was new to the practice. She had been working with Roth just three days before the crash.

"They were a family, and they've been together for a really long time," Vidal-Smith said.

Roth and his team treated patients for varicose veins, spider veins and other vascular diseases affecting the legs. The doctor would see patients a few days each week in Augusta, then use the jet for day-trips to treat patients at the other clinics.

"It was a natural course of business for him," Vidal-Smith said.

Investigators for the National Transportation Safety Board returned Friday to the crash site about a half-mile from the small, private airport in Thomson, about 30 miles west of Augusta. The NTSB quickly determined the plane overshot the runway and hit a concrete utility pole, tearing off the jet's left wing and causing fuel to leak and burst into flames. NTSB board member Robert Sumwalt said that much of the wreckage was in small fragments str ewn over 100 yards and that most of the plane had burned.

What remains unknown is why the jet's pilot aborted the landing. The jet approached the runway under clear skies. Flight records confirmed the plane had made the same trip many times, Sumwalt said Friday, and air traffic controllers in Augusta received no distress calls.

Pilots would typically notify air traffic controllers of mechanical malfunctions or emergencies, Sumwalt said.

Sumwalt said experts in Washington would take a closer look at video from a motion-activated security camera at the airport that caught only a brief and grainy glimpse at the jet.

Investigators had also paid a brief visit to one of the hospitalized pilots, Sumwalt said, but detailed interviews about what happened before the crash would have to wait.

"Obviously, they've got the firsthand accounts of what happened, as best as they can remember them," Sumwalt said. "But you can't just go storming into a hospital and conduct an interview."

One of the pilots, Richard Trammel, was upgraded to fair condition Friday at Georgia Regents Medical Center in Augusta. The name of the second pilot had not been released by authorities, and his condition remained unknown.

Joshua Williams, a fellow charter pilot, said he had known Trammel for 18 years.

"He's a very experienced pilot, a very skilled pilot with many, many years of expertise," Williams said, though he declined to comment further.