NTSB briefing:
crew briefed ils approach to 23 Buffalo
discussed vis 3m snow and mist
at 16000 vis hazy so requested 12000
shortly after cleared to 11000
FDR showed airframe de-ice selected on, followed by a cockpit discussion of significant ice on windshield and leading edge of wings
final events timeline:
end-of-recording minus 1 min: landing gear selected down
eor minus 40 secs :flaps 15 selected
"within seconds of flap selection": "series of severe pitch and roll excursions"
"shortly after that" : crew attempted to raise flaps and gear "just before the end of the recording"