(AP) - The crew of a commuter plane that fell outof the sky, killing all 49 people aboard and one person on theground, noticed significant ice buildup on the wings and windshieldjust before the plane began pitching and rolling violently,investigators said Friday.

Officials stopped short of saying the ice buildup causedThursday night's crash and stressed that nothing has been ruledout. But ice on a plane's wings can interfere catastrophically withan aircraft's handling and has been blamed for a number of majorair disasters over the years.

Continental Connection Flight 3407 from Newark, N.J., went downin light snow and fog late Thursday and crashed into a house insuburban Clarence. Killed were 44 passengers, four crew members,one off-duty pilot and one person on the ground.

Two others escaped from the home, which was engulfed in adramatic fireball that raged higher than the treetops and burnedfor hours. Bodies still could not be recovered hours later.

The plane went through a "severe pitch and roll" experienceafter positioning its flaps for a landing, said Steve Chealander,spokesman for the National Transportation Safety Board.

Doug Hartmayer, a spokesman for Niagara Frontier TransportationAuthority, which runs the airport, said: "The plane simply droppedoff the radar screen."

No mayday call came from the pilot before the crash, accordingto a recording of air traffic control's radio messages captured bythe Web site LiveATC.net. Neither the controller nor the pilotshowed concern that anything was out of the ordinary as theairplane was asked to fly at 2,300 feet.

Federal investigators recovered the black box recorders from thesmoldering wreckage Friday and returned them to Washington. The74-seat Q400 Bombardier aircraft, in the Dash 8 family of planes,was operated by Colgan Air, based in Manassas, Va. Colgan's parentcompany, Pinnacle Airlines of Memphis, Tenn., said the plane wasnew and had a clean safety record.

The pilot, Capt. Marvin Renslow, had been with the airline fornearly 3½ years and had more than 3,000 hours of flying experiencewith the carrier. The associate pastor at Renslow's church north ofTampa said in a statement on behalf of Renslow's family that thepilot died doing what he loved.

"They're very proud of Marvin's accomplishments as a pilot.They know that he did everything that he could to save as manylives as he could, even in the accident. Marvin loved to fly,"said Alan Burner of the First Baptist Church of Lutz.

Flight 3407 is the first fatal crash of a commercial airliner inthe United States since Aug. 27, 2006, when 49 people were killedafter a Comair jetliner mistakenly took off from a Lexington, Ky.,runway that was too short.

The crash came less than a month after a US Airways pilot guidedhis crippled plane to a landing in the Hudson River in New YorkCity, saving the lives of all 155 people aboard. Birds hadapparently disabled both its engines.

In general, smaller planes like the Dash 8, which uses a systemof pneumatic de-icing boots, are more susceptible to icing problemsthan larger commuter planes that use a system to warm the wings.The boots, a rubber membrane stretched over the surface, are filledwith compressed air to crack any ice that builds up.

A similar turboprop jet crash 15 years ago in Indiana was causedby icing, and after that the NTSB issued icing recommendations tomore aggressively use the plane's system of pneumatic de-icingboots. But the FAA hasn't adopted it. It remains part of the NTSB'smost-wanted safety improvements list.

Clarence is a growing eastern suburb of Buffalo, largelyresidential but interspersed with rural stretches. The crash siteis on a street of older, single-family homes about 20 to 25 feetapart that back up to a wooded area. While residents of theneighborhood were used to planes rumbling overhead, witnesses saidit sounded louder than usual, sputtered and made odd noises.

"It didn't sound normal," said David Luce, who was at homewith his wife when they heard the plane come in low. he said. "Weheard it for a few seconds, then it stopped, then a couple ofseconds later was this tremendous explosion."

Dworak drove to the site, and "all we were seeing was 50- to100-foot flames and a pile of rubble on the ground. It looked likethe house just got destroyed the instant it got hit."