National Transportation Board spokesperson Steve Chealander speaks during a news conference about the crash of Continental Connection Flight 3407 on Saturday. (Frank Franklin II/Associated Press)The early stages of the investigation into the crash of Continental Airlines Flight 3407 indicate something prompted the plane to belly-flop on top of a home northeast of Buffalo while not even facing the runway it was expected to reach within minutes, according to U.S. officials.

The plane did not nose dive into the house it landed on, as initially thought, Steve Chealander, spokesman for the National Transportation Safety Board, told a news conference on Saturday.

The New Jersey-to-Buffalo flight had already been cleared to land at the time of the crash, Chealander said. The runway was southwest of the crash location, while the plane's nose was pointed northeast, Chealander said.

Fifty people died on Thursday night due to the crash; 49 people were on the plane while one resident in the home it crashed into also perished.

Investigators began removing the bodies of victims from the crash site on Saturday.

Plane sitting flat

The way the plane is lying on the crash site is the way an aircraft would sit if it were flat on the ground, said Chealander. The plane is not oriented as if it were in a nose dive, despite witness reports that it appeared to be angled down during its final descent, he said.

"It is not oriented as a nose-down accident would take place. It is also oriented in the opposite direction it was landing," he said.

Analysis will be done to determine if the plane was in a flat spin when it struck the house, he said.

Investigators are expected to remain on site for at least a week before the plane's parts are taken away for analysis, Chealander said.

It will take up to a year before a full report on the crash is released, he said.

"We're in the very early stages of the investigation."

Bodies being recovered

An aerial view of the tail section of Continental Connection Flight 3407 as it sits amid smoking wreckage on Friday. (Associated Press)Removing the victims from the site is the current priority, he said. DNA and dental samples will be used to establish the identities of the recovered remains, he said.

Due to the catastrophic nature of the crash and the ensuing fire, it could take up to four days to remove all the human remains, Chealander said.

More than 100 investigators from the NTSB and the Federal Bureau of Investigation were at the scene in Clarence Center, where the 74-seat Q400 Bombardier turboprop craft crashed.

The airplane and the house have become mingled together and the scene has become an excavation site, Chealander said.

Residents from 12 other homes evacuated because of the fire Thursday night were being escorted back Saturday to collect some of their belongings and leave for what is expected to be another three to four days before the evacuation order is lifted.

Authorities said they don't want anyone not associated with the investigation to be within two kilometres of the crash site. Local emergency official David Bissonette said any violators will be charged with trespassing.

"There's going to be no pictures, no YouTube videos," he said. "It's literally for the residents to get the items they need and then they have to get out."

Ice buildup a possible cause of crash

Investigators have been examining instrument data and have listened to the last words of the pilot and co-pilot to determine whether ice on the wings caused the crash.

Officials say the crew of the Continental Connection flight remarked on significant ice buildup on the wings and windshield shortly before the aircraft pitched violently and crashed.

Ice on the wings can interfere catastrophically with an aircraft's handling and has been blamed for a number of major air disasters over the years.

Chealander said the icing noted by the pilot of Flight 3407 is just one of several things investigators are looking at.

But the de-icing system on the plane was activated and based on flight recordings, the crew appeared to believe it was functioning properly, he said.

A cursory inspection of the engines also indicates both were functioning properly at the time of the crash, Chealander said.

But if ice is a problem in flight, guidelines from the Aircraft Owners and Pilots Association Air Safety Foundation say pilots can take a number of steps, including changing speed, pulling the nose up or down, or trying a 180-degree turn.

Stall protection system engaged

Chealander said two stall-protection systems, known as the stick shaker and the stick pusher, had activated on the aircraft. It is not yet clear if the plane stalled, he said.

The systems activate when the airflow over the wings is not enough to keep lift and are meant to warn the pilot of an impending aerodynamic stall, he said.

If the pilot doesn't take action when the yoke starts to shake, the stick pusher activates and forces the nose of the aircraft down to change altitude in an attempt to recover from the impending stall, he said.

The aircraft went also through a "severe pitch and roll," he said.

"It was just a sudden catastrophic event that took place and 30 seconds later they ended up on the ground," he said, adding that there is no indication that the crew spoke with the passengers just before the crash.

Flight 3407 went down in light snow and mist — ideal icing conditions — about nine kilometres short of the airport.

Canadian among victims

The crash site was engulfed in a fireball that burned for hours, making it too hot to begin removing the bodies until nightfall Friday.

Recovery teams first had to spend hours using heaters to melt the ice that had formed over the crash site after firefighters had worked tirelessly to put out the massive blaze on the scene, Chealander said.

Don McDonald, a Canadian returning home to Fort Erie, Ont., from a business trip, was among the passengers.

Other victims included human rights researcher Alison Des Forges, who documented the 1994 genocide in Rwanda; Beverly Eckert, whose husband was killed in the attacks on the World Trade Center on Sept. 11, 2001; and two members of jazz musician Chuck Mangione's band, Gerry Niewood and Coleman Mellett.

With files from the Associated Press