Buffalo, N.Y. ? Every time ice is suspected of bringing down a plane, the volume rises on how best to protect aircraft from the all-too-common and all-too-disastrous phenomenon. And each time, the conversation fades before significant changes are made.

Authorities caution that they’re still investigating why Continental Connection Flight 3407 dropped out of the sky onto a house Thursday night, killing 50 people. But recordings show the crew was concerned about ice buildup on the windshield and wings shortly before the crash.

With planes carefully designed for aerodynamics, a buildup of ice can affect their lift and handling. A crash blamed on ice killed 68 people in 1994 in Indiana, another killed 29 people in 1997 in Detroit.

Investigators know the Buffalo plane’s deicing system was turned on and say it appeared to be working. What they don’t know is when it was activated or how much time the pilot had to react.

Pilots of turboprop planes like those in the Buffalo-area crash must turn on their deicing equipment when they notice buildup. The NTSB wants to go a step further and require them to turn the equipment on when conditions are right for icing.