BUTTE – Investigators say they are looking at a pilot’s decision to divert his plane to a different airport shortly before it crashed as a potentially crucial factor in determining the cause of a plane crash in Butte.
Flying at 25,000 feet, pilot Buddy Summerfield requested the diversion from Bozeman, Mont. to Butte just half an hour before the single-engine Pilatus PC-12 nose-dived into a cemetery at the edge of Butte’s airport Sunday. Fourteen people including seven children under the age of 10 were killed.
National Transportation Safety Board acting Chairman Mark Rosenker says why the plane diverted is at the forefront of his agency’s investigation.
“It begins with that question — 25,000-foot diversion to go to Butte,” Rosenker said.
Rosenker also revealed that the plane’s landing gear was down but its wing flaps were up at the time of the crash. That’s unusual for a landing aircraft but not unheard of, said the investigator in charge of the accident, Dennis Hogenson
Also under scrutiny are weather conditions that could have caused icing on the plane’s wings and possible overloading. The plane was configured to seat just 10 people.
The investigation has been hampered be the lack of a cockpit voice recorder or data recorder, which were not required on the private flight. Rosenker said his agency may subpoena cell phone records of the victims to see if they could provide further clues.
Federal officials on Tuesday gave a few reporters and photographers the first close look at Sunday’s crash site.
Working among rows of charred granite headstones cordoned off by yellow police tape, investigators removed the last of the victims’ luggage as they combed through the wreckage. Shredded metal, pieces of propeller and a seat cushion were among the few discernible items left at the scene.
Small pieces of debris were picked up, logged and placed in plastic bags. The larger pieces, including a wing and a section of the plane’s tail, will be removed by the end of the week and taken to a Montana hanger for inspection.
Most of the wreckage was confined to a small area, consistent with witness reports that the plane nose-dived straight into the ground.
While descending toward Butte’s Bert Mooney Airport, the plane passed through a layer of air at about 1,500 feet that was conducive to icing because the temperature was below freezing and the air “had 100 percent relative humidity or was saturated,” according to AccuWeather, a forecasting service in State College, Pa.
Safety experts said similar icing conditions existed when a Continental Airlines twin-engine turboprop crashed into a home near Buffalo Niagara International Airport last month, killing 50.
A possible stall created by ice — and the pilot’s reaction to it — has been the focus of the Buffalo investigation, which remains open.
An NTSB spokesman said it was too early to single out any one factor in the Butte crash.
“To say that icing is becoming the lead focus is not true at this point,” said spokesman Keith Holloway. “We’re looking at mechanical issues. We’re looking at weather. We’re looking at the structure of the aircraft. We’re looking at human performance, weight and balance issues.”
Since 2001, federal authorities have investigated fifteen crashes involving PC-12’s. Six involved fatalities, with a total of 14 killed prior to Sunday’s crash.
There is no radar data of the plane’s final moments for investigators to examine because, like thousands of small airports, the Butte airport doesn’t have radar. The radar at the FAA’s en route center in Salt Lake City, which handled the flight’s last leg, doesn’t extend as far as the Butte airport.
The last radio communication from the turboprop’s pilot was with the Salt Lake City center when the plane was about 12 miles from Butte, said Doug Church, a spokesman for the National Air Traffic Controllers Association. Minutes before the crash, the pilot told controllers he intended to land at Butte using visual landing procedures rather than relying on instruments, which is not unusual, Church said.
The pilot said nothing to controllers to indicate he was having trouble, including during radio conversations earlier in the flight when the pilot notified controllers he intended to divert from the flight’s original destination of Bozeman, Mont., to Butte, about 75 miles away.
“We don’t know the reason for the requested change to the flight plan,” Church said.
Former NTSB chairman Jim Hall said there were similarities between the Montana crash and a 2005 crash near Bellefonte, Pa., that killed a pilot and five passengers. The plane in both cases was a Pilatus PC 12/45, and in both there were reports of conditions conducive to icing at lower elevations and witness reports that the plane appeared to dive into the ground.