AMHERST, N.Y. -- The crew of the plane that crashed near Buffalo on Thursday night discussed a “significant ice buildup” on the wings and windshield as the aircraft descended through light snow and mist, according to the flight data and voice recordings recovered from the scene of the accident that killed all 49 people on board and one person on the ground.

In a late afternoon news conference, Steven Chealander of the National Transportation Safety Board, who is acting as spokesman for the crash investigation, shared the chilling, technical details of the final minutes of Continental Flight 3407 as it prepared to land at Buffalo International Airport, which federal investigators gleaned from listening to the tapes on Friday.

In the final minute of the flight from Newark Liberty International Aiport, Mr. Chealander said the pilots apparently tried to abort the landing, but the plane violently pitched and rolled and seconds later crashed into a house in Clarence Center, N.Y., a Buffalo suburb six miles from the airport.

“The crew commented at 16,000 feet that they noticed it was rather hazy and requested to descend to 12,000 feet, and shortly after that request, they were cleared to 11,000,” he said. “Around that time, the crew discussed significant ice buildup, on the windshield and leading edge of the wings.”

He said that the de-icing system had already been in the on-position when the crew discussed the ice on the plane. The plane continued its descent, and the crew lowered the landing gear with a minute left on the tape.

Forty seconds later, the pilots extended the flaps, the moveable panels on the rear edge of the wings that allow a plane to maintain lift as it slows. But within seconds of extending the flaps, the plane experienced “severe pitch and roll excursions,” meaning that the nose pointed up and down and the wings wagged from side to side, said Mr. Chealander.

“After that,” he said, “the crew attempted to raise the gear and flaps just before the end of the recording.”

Mr. Chealander, a former airline captain, emphasized that the board was in a “fact-gathering stage” and would not analyze the data now. However, the sequence he described is consistent with previous crashes caused by icing.

There is no indication so far that the weather was unusual for Buffalo in February. Visibility around the airport was three miles, with snow and mist. “That’s icing conditions,” Mr. Chealander said.

The airplane, a Bombardier Dash 8 Q400 with two turboprop engines and room for 74 passengers, is certified for flight into “known icing conditions.” But when the pilots change the shape of the wings, by moving the flaps or other controls, sometimes buildups of ice that were not a factor in an earlier configuration are suddenly exposed to the passing wind and make the plane uncontrollable.

Image An undated image provided by Google Maps of the home at 6038 Long Street in Clarence, N.Y. Credit... Google Maps, via Associated Press

The flight data recorder was unusually comprehensive, measuring 250 different data points at frequent intervals, including use of the anti-icing system, but it did not record whether that system actually worked. On the Dash 8, a turboprop, the anti-icing system consists mostly of rubber, tire-like pneumantic “boots,” said Mr. Chealander. These “boots” inflate and shrink, breaking off accumulations of ice from the forward edges of the wings.

While investigators in Washington continued to comb through the tapes for causes of the crash, investigators on the ground were searching for clues from the aircraft and for remains of the victims.

Everyone aboard the plane -- including 44 passengers, a crew of 4 and an off-duty airline employee -- and one person in a house destroyed by the plane was killed, said Chris Collins, the Erie County executive.

Two others in the house, a 57-year-old woman and her 22-year-old daughter, suffered minor injuries and were taken to a nearby hospital, where they were treated and released, officials said.

Among those on the flight was Alison L. Des Forges, a historian and human rights advocate who documented the 1994 genocide in Rwanda and investigated related issues in Burundi and Democratic Republic of the Congo, according to Emma Daly, communications director of Human Rights Watch in New York City.

Also on the flight was Beverly Eckert, the widow of Sean Rooney, a Buffalo native who died at the World Trade Center in the terror attacks of Sept. 11, 2001.

Ms. Eckert was on her way to Buffalo for a weekend celebration of what would have been her husband’s 58th birthday, and had planned to take part in the presentation of a scholarship award at Canisius High School that she had established in his honor, The Buffalo News reported.

Ms. Eckert met President Obama last week at the White House, along with other relatives of people killed in the 2001 attacks or the bombing of the U.S.S. Cole.

Speaking at the White House late Friday morning, Mr. Obama said that Ms. Eckert “was an inspiration to me and to so many others, and I pray that her family finds peace and comfort in the hard days ahead.”

Continental Airlines said the pilot of the flight, Continental Connection Flight 3407, was Capt. Marvin Renslow, 47, from Lutz, Fla.; the first officer was Rebecca Shaw; flight attendants were Matilda Quintero and Donna Prisco; and the off-duty employee traveling on the flight was Capt. Joseph Zuffoletto.

The flight was operated by Colgan Air under contract to Continental, and it has been using that type of plane since February 2008.

Image Among those on board was Beverly Eckert, the widow of Sean Rooney, who died in the Sept. 11 attacks on the World Trade Center, according to The Buffalo News. Credit... Douglas Healey/Associated Press

Among those on the flight was Maddy Loftus, 24, from Parsippany, N.J., who was traveling to a reunion of the women’s ice hockey team at Buffalo State College, said Jeff Ventura, the sports information director at the school. Ms. Loftus was the first girl on the Parsippany Hills High School boys’ ice hockey team, before playing forward for Buffalo State from 2002 to 2004, and then at St. Mary’s University in Minnesota.

Her father, Mike, flew for years as a pilot for Continental Airlines, according to several news reports.

Two members of Chuck Mangione’s band, Coleman Mellett, a guitarist, and Gerry Niewood, a saxaphonist, also were among the victims, according to the Associated Press.

In Buffalo, employees at the 600-person office of Northrop Grumman, a defense contractor, Jack Martin, a spokesman for the company, confirmed that four colleagfues had died in the crash, but he declined to release their names.

The death of Cantor Susan Wehle, from Temple Beth Am in Williamsville, N.Y, was confirmed by the Jewish Federation of Greater Buffalo. According to the Temple’s Web site, she had in 2006 recorded a CD of her work, “Songs of Hope and Healing.”

Clay Yarber, 62, a Vietnam veteran who had twice survived helicopter accidents during the war, also died in the crash.

"That is one of the bitter ironies of all this for us," a former wife, Michele Keratsis, said in a telephone interview. She said that after his service in Vietnam, "he was not happy to get on a plane at anytime."

At a command center where officials gathered after the accident, Chris Kausner told CNN that his sister, Ellyce Kausner, was on the flight. He said she was connecting from Jacksonville, Fla., where she was a law student. When a reporter asked Mr. Kausner how his family was taking the news, he said: “I heard my mother make a sound into the phone that I had never heard before. So, not good.”

An intense fire at the site of the crash, fueled by a natural gas leak, initially made it difficult for the investigators to retrieve the voice and data recorders, Mr. Chealander said. Fourteen investigators from the board are at work seeking the cause of the crash, he said at a news conference on Friday morning.

Tony Tatro, who lives near the crash site, told CNN that he was driving home when the plane passed about 75 feet overhead, with its nose pitched lower than normal and its wings tilted. The plane struck the ground moments later, he said.

The plane took off nearly two hours late from Newark Liberty Airport at 9:19 p.m. and crashed about 10:20 p.m. Eastern time, five minutes before it was due to land. David Bissonette, the emergency coordinator for the town of Clarence Center, told reporters around 4 a.m. that the plane had made “a direct hit” on the house at 6038 Long Street in Clarence Center.