Forensic anthropologists and aviation experts are walking grids in Clarence Center, where Flight 3407 went down, trying to determine what caused the craft to take a horrific vertical dive.
It's grim work.
Each spot where human remains, pieces of the aircraft and personal effects are recovered will be specially marked with a flag and then electronically recorded in each grid, so that investigators can find out exactly how the craft ended up in a fiery crash.
Did it directly hit the Long Street house destroyed in the crash?
Did it hit both the house and the lot surrounding it?
Or -- perhaps the most frequently asked question -- did icing on the wings cause the crash?
Those are some of the questions investigators want to answer.
The human remains will be taken to the Erie County medical examiner, where extra capacity has been added with a temporary morgue set up inside a refrigerated trailer.
Investigators at the medical examiner's Buffalo office will attempt to identify the individuals lost in the flight. In some cases, DNA testing will play a significant role, authorities said.
"In some cases, we'll need to use DNA [to identify victims], in some cases, maybe we won't," said Dr. Anthony J. Billittier IV, Erie County's health commissioner, who visited the site Friday afternoon.
Authorities said late Friday that the actual DNA analysis would be performed by the Armed Forces Pathology Laboratory in Washington, D.C.
Physical evidence such as parts of the plane will be examined by National Transportation Safety Board investigators and FBI agents.
And as early as next week, law enforcement may be able to say whether criminal activity or terrorism was involved in the Thursday night crash, according to Laurie J. Bennett, special agent in charge of the Buffalo FBI office.
She says at this point it does not appear to be anything more than a tragic accident, though more evidence is needed to rule out any type of foul play.
Of those lost on the flight, Bennett said:
"FBI agents, NTSB personnel and all our law enforcement partners will treat the scene with much respect and care, ensuring that the proper dignity is provided to the victims of this tragic crash when collecting the human remains."
Bennett also said that special care will be taken in retrieving as many personal effects of the victims as possible, to be eventually returned to their loved ones.
"That's being done in the hopes that the families can obtain closure in the many months and years ahead," she said.
Unlike other commercial plane crashes, Bennett said, the debris field in this one is tiny by comparison. It takes up the house and property lot of the Long Street residence.
But that does not mean the search for evidence will be any less thorough.
Working with investigators at the scene is a special team of forensic anthropologists from Mercyhurst College in Erie, Pa., which includes two professors and several trained students.
"Essentially the process is cordoning off grids and in each grid identifying any victims. It's not clear how long it will take, we've just started doing it," Billittier said.
Billittier said officials understand the wishes of victims' families to visit the crash site, and the challenge is conducting a thorough investigation expeditiously. He noted there are multiple investigations occurring on-site simultaneously.
"We're conducting a medical and legal investigation; the NTSB is conducting the mechanical investigation, and law enforcement is conducting a criminal investigation," Billittier said. "The on-scene recovery of remains takes a few days. It's a matter of days, not hours."
He said as many as 75 people were sifting through the debris for remains in an effort to find all of the human remains, proceed with DNA analysis and confirm victims' identification.
"The success or failure of this, I believe, will be judged by how much comfort we bring to the families," Billittier said.
Erie County Executive Chris Collins, who was at the crash scene late Thursday night and flew over it at 9 a.m. Friday, explained that the teams will walk in grid lanes with as many as 20 individuals scouring each path for evidence.
"These are professionals," he said.
Investigators will take data from the grids and create a computer model of the crash scene that they will be able to refer to as the investigation progresses.
Collins, who lives two miles from Long Street, said it was impossible to see sections of the aircraft in the blaze Thursday night from the road.
"I was taken behind the house and the only part of the plane I could see was the tail," he said.
In emphasizing just how contained the crash site was, Collins said, "The garage was right behind the house and it was intact. Only one other house, next door, received collateral damage from flames."
It has been estimated that it may take a week, if not more, to complete the collection of evidence from the site, law enforcement officials said.
In the meantime, aviation experts say they expect the NTSB will soon start providing hints about the cause of the crash.
"Once they get radar data, weather data and information from the flight recorders, they will start piecing things together," said Peter Goelz, who has supervised the investigations of several major aircraft disasters. "As they recover pieces of the plane, they will look at it and start eliminating possibilities.
"Are all the engines still there? Were they still making power when the plane crashed? Were the flaps, the elevators and everything else working as they should be? You look at every option, and then you eliminate [possible causes], one by one."
Goelz, who served as managing director of the National Transportation Safety Board from 1995 until 2000, stressed Friday that while it is too soon to pinpoint the cause, most signs -- including weather conditions and the way the plane suddenly plummeted to the ground -- seem to point to ice on the wings.
"The suddenness of the [descent] makes you suspicious of icing as the cause," Goelz said. "One minute, you have a plane flying smooth and level at 2,300 feet. The next minute, it's on the ground."
That kind of sudden crash can be caused by ice on the wings, he said. "It's also significant that the next two planes that came in to Buffalo reported icing problems."
Now working as a consultant to aviation companies, Goelz said the Bombardier Dash-8 Q400 turboprop plane model that crashed gets heavy use from commuter aviation companies and never before has had a fatal crash in the United States.
"It is considered a fine aircraft. It's very quick, almost as fast as a regional jet, but much cheaper to fly," Goelz said of the Bombardier.
Such planes do have de-icing systems on them, but the de-icing system has to be activated by the pilot. Goelz said it would be highly unlikely that the veteran pilots of Flight 3407 would have failed to do so, especially considering Thursday night's weather.
"Certainly this plane was certified to fly in this kind of weather. If the de-icing system was working, it should have been able to handle the weather," Goelz said. "That's why there is an air of mystery to this tragedy."
Buffalo attorney Paul J. Cambria, whose law firm has represented a number of air crash victims, predicted that there could be numerous lawsuits filed by victims' families if icing is found to be the cause of the disaster.
"It could be that something went wrong with the de-icing equipment, or there was pilot error, or both," Cambria said. "Either way, it's a horrible tragedy. Either way, the passengers had a right to assume that the plane was in good working order, and that the weather conditions were thoroughly checked before the plane took off."
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