Crews have finished gathering human remains where a commuter plane crashed into a house and exploded outside Buffalo, N.Y.
Dr. Scott Zimmerman of the Erie County Health Department said the office wrapped up its work at the site Tuesday afternoon.
Continental Connection Flight 3407 crashed Thursday night. All 49 people aboard were killed. One person in the house it struck also died.
Zimmerman cited respect for victims' families in declining to say how many passengers' remains have been identified.
But he says he is confident all have been taken from the site.
Control of the crash site now shifts from the medical examiner to the National Transportation Safety Board.
Investigators, meantime, are scrutinizing the pilot's actions in the final moments of the flight to determine whether anything on the airplane broke mid-flight.
Though ice has emerged as a possible factor, the cause has remained elusive in part because there was no distress call from the pilot, no mechanical failure has been identified and the plane was so severely damaged.
More than 2,000 people, including relatives of the victims, turned out for a community prayer service Monday.
"We feel it's a miracle that more houses weren't destroyed and more people killed," said Ora Ganschow, 79, who lives four blocks from the site.
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Wearing blue dress uniforms, members of the Clarence Center Volunteer Fire Co. carried single long-stemmed roses -- one for each victim -- to the altar, placing them into a crystal vase as a soloist sang "Amazing Grace."
Authorities said gawkers continue to be a problem, forcing officials to again close a road that leads to the suburban Clarence neighborhood. Three people have been arrested, including a man caught hiding behind a home and videotaping the crash site Friday.
Crash probe focusing on weather, crew's training
The pilot of Continental Connection Flight 3407 had spent only 110 hours flying that model, and investigators said Tuesday they would look into the quality and quantity of his training.
Investigators say so far that it appears that Capt. Marvin Renslow did nothing wrong before the final violent plunge to Earth in icy weather. Experts pointed out Tuesday that he had flown thousands of hours in a similar plane, which would have prepared him for such conditions.
The actions and even the lives of Capt. Renslow, 47, of Tampa, Fla., and the first officer, Rebecca Lynne Shaw, 24, of Seattle, are under close scrutiny as the National Transportation Safety Board tries to piece together how a routine flight went fatally wrong in its last 26 seconds.
The NTSB will look into the type of training they received, how they performed, how many hours they flew in the seven days before the crash, how much rest they had and what they did in the 72 hours before the accident, said board member Steve Chealander. That includes whether they drank any alcohol or took drugs.
Another NTSB investigator left in Buffalo will focus on any role the wintry weather had. Other investigators stayed in Buffalo to interview pilots who had recently flown with Renslow and Shaw; many fly regularly into the area.
With no obvious answer to the crash, the NTSB was preparing for a yearlong study of everything related to the plane and its cockpit crew to find out what combination of factors can eventually be blamed for the disaster.
It appears Renslow disregarded the NTSB's and his airline's recommendation that autopilot not be used in icy conditions, Chealander said, adding that the decision did not violate airline rules because shutting off the autopilot is required only in severe icing conditions.
Renslow had begun flying the Dash 8 in December, accumulating 110 hours since then; Shaw had 774 hours in the plane model. Chealander stressed that pilots must train rigorously every time they switch plane types and that the relative lack of hours would not be considered significant.
Pilots are ordered to do about five weeks of training on a new aircraft, including oral examinations, simulator training and required time flying with another certified pilot, Chealander said.
"The training is very strict," he said. He said he sweated all five times he tested for a new aircraft.
"I still get nervous for it," Chealander said.
Colgan Air, based in Manassas, Va., did not return a call Tuesday seeking comment on training procedures. Renslow had 3,000 hours of flying experience with Colgan over 3 1/2 years, which is nearly the maximum a pilot can fly over that period of time under government regulations.
Shirley Phillips, associate professor of aviation sciences at Daniel Webster College in Nashua, N.H., has piloted a plane that Renslow had a lot of experience flying. It was a Saab twin-engine turboprop, a type Renslow flew for thousands of hours before he switched late last year to the Dash 8.
"They're both turboprops," she said. "As far as flying in icing conditions there really isn't anything you would do differently. The deicing mechanisms are the same."
The rules for flying in ice would also be the same, she said, adding that Renslow might have made a mistake when he opted to stay on autopilot even after noticing significant icing on the wings and windshield, as indicated by recordings.
Phillips also said it was not encouraging that an automatic safety mechanism meant to prevent a stall forced the autopilot off just before the plane hurtled earthward.
"The airplane shouldn't have gotten to those conditions where it turned the autopilot off," Phillips said.
Johnny Summers, a pilot on a Boeing 737 who has also flown turboprop planes, said flying in ice is fairly routine; planes are designed for it and pilots trained for it. However, Summers recalled that a few years ago, while flying a Twin Otter into Colorado Springs, he was forced to land about 60 miles short because of severe ice. The aircraft is a twin-engine turboprop that seats as many as eight, while the Dash 8 Renslow was flying could seat 74.
He could not remember whether the crew turned off the autopilot, but said all deicing and anti-icing equipment was immediately turned on.
"I wasn't nervous about it," Summers said. "It's not that spooky of a thing."
John Hansman, a Massachusetts Institute of Technology professor who specializes in flight safety, said it was fair to focus on the autopilot as an issue because "that is the only thing so far that is against recommended procedures."
The NTSB's Ward said the agency was sending investigators across the country to interview those who supervised Renslow and Shaw and anyone who had trained them.
"In most investigations, people describe the flight crew as being very good," she said.
Investigators, though, know that the challenges in a sky emergency might be beyond anyone's capabilities.
"It comes down to, we're all human," she said.