Crew members of Continental Connection Flight 3407 were talking about ‘significant ice buildup’ shortly before the plane dived into a one-home house, killing all 49 aboard and 1 man in the house on Thursday, authorities said on Friday.

Stephen Chealander, a spokesman for the National Transportation Safety Board (NTSB), told a press conference that cockpit voice recording shows that the crew were discussing ice buildup on the windshield, although the pneumatic icing boots were switched on.

When turned on, pneumatic icing boots would usually expand and break free ice that has developed at the wings’ edges, he said.

Chealander said authorities are still sifting through the wreckage at the site to recover the remains of the victims.

Both data and voice recorders, or black boxes, of the plane have been recovered and sent to Washington for further analysis.

The crash occurred at around 10:20 p.m. Thursday (0320 GMT Friday) in suburban Buffalo in northern New York state, nearly a seven-hour drive from New York City.

The 50-seat commuter plane, Continental Express Flight 3407 operated by Colgan Air, was flying from Newark to Buffalo.

The crash is reportedly America’s deadliest since a Comair commuter jet crashed in Lexington, Kentucky on Aug. 27, 2006, killing 49 people.