The crew of the prop jet involved in the worst U.S. plane crash in seven years went from "complacency to catastrophe" in seconds because of inexperience, cockpit distractions and possible fatigue, the government said Thursday.

The National Transportation Safety Board spent the final day of three-day hearings questioning medical experts and federal regulators from the FAA on how they can tackle problems with pilot fatigue, training, long commutes and distractions in the cockpit.

The NTSB is investigating how to prevent accidents like the Feb. 12 crash of Continental Connection Flight 3407 in upstate New York that killed 50.

"This crew went from complacency to catastrophe in 20 seconds," NTSB member Debbie Hersman said during opening testimony on Thursday. "They didn’t see it coming."

The commuter airline, operated by Colgan Air, plunged into a house on an icy night during its approach into Buffalo, killing all 49 on board and one inside the home.

Click here for crash photos.

Click here for the cockpit voice recorder transcript (pdf).

The twin-engine turboprop was nearing Buffalo Niagara International Airport at night in wintry conditions when it suffered an aerodynamic stall, rocked back and forth, then took a nose-dive.

The captain and co-pilot were distracted and might have realized they were traveling at dangerously low speeds if they had a warning system, safety officials said Thursday.

Hersman raised the issue of a warning system in questioning NASA scientist Robert Dismukes, an expert on cockpit distractions.

She noted that Flight 3407 lost 50 knots of airspeed in 20 seconds while Captain Marvin Renslow, 47, and co-pilot Rebecca Shaw, 24, chitchatted on approach into the airport.

A cockpit voice recorder transcript shows Renslow and Shaw discussing careers and her lack of experience flying in icy conditions during the plane's final minutes, even after they had noticed a buildup of ice on the windshield and wings.

Dismukes agreed that the voice recorder shows the two were distracted, not realizing their danger until a stall warning system that violently shakes the pilot's control column went off.

He said that probably grabbed Renslow's attention and he may not have realized even then how low the aircraft's speed had dropped.

Asked by Hersman if pilots might benefit from an audible low-speed warning system, Dismukes said: "Absolutely. You want a very distinctive alert, but not one that is so dramatic. That's well worth looking at."

Hersman said the stick shaker warning came too late and was too sudden.

"The room is on fire at that point," she said.

Seven seconds after the stick shaker went off, with Renslow apparently still wrestling with the control column, the plane's stick pusher kicked in, a second system that automatically points the aircraft's nose downward in response to an aerodynamic stall, which means the plane lost lift.

The board has not concluded what initially caused the plane to decelerate to a dangerously low speed, but it followed actions by the flight crew to slow the plane in preparation for landing.

Testimony indicated that Renslow, who was relatively new to that type of aircraft, might not have realized how quickly the plane decelerates, especially if he were distracted.

The board recommended to the Federal Aviation Administration in December 2003 that regulators study whether an audible low-speed warning system designed to get a pilot's attention should be required.

FAA responded in 2006 that it had formed a team to study the issue and hoped to have results in 2007.

The board made the recommendation in response to a 2002 air crash in Minnesota in which Sen. Paul Wellstone and some family members were killed.

The NTSB concluded in that crash that the flight crew of the charter plane failed to realize that the King Air A100, a small twin-engine turboprop, had slowed to a dangerously slow speed in preparation for landing. The low speed caused an aerodynamic stall, resulting in that crash.

Some aircraft already have audible low-speed warning systems that say "speed, speed, speed ..." The Bombardier Dash 8-Q400 in the Buffalo crash didn't have an audible warning system, although it had a low speed "barber pole" warning system that changes color.

The NTSB's three days of hearings this week have raised several safety issues involving pilot training, hiring and pay.

Shaw lived near Seattle with her parents, but worked out of Newark, N.J., where the flight originated.

Renslow was commuting to Newark from his home near Tampa, Fla.

Dismukes testified Thursday about the impact of fatigue, saying, "it does affect our attention."

Dismukes also said conversation in the cockpit can be a major distraction, and proposed that pilots be better trained on how to manage their attention.

"We need to develop ... specific techniques that pilots can use," Dismukes said.

Transcripts taken from the flight data recorder showed Renslow and Shaw were engaged in conversation just moments before the plane crashed into a house five miles from the airport — which violated the sterile cockpit rule, an FAA regulation requiring pilots to refrain from non-essential activities below 10,000 feet.

The flight was operated for Continental by Colgan Air of Manassas, Va., a regional carrier.

Their lack of experience is also at issue. Renslow failed several training check rides before being hired by Colgan but didn't disclose that information to the company.

On Thursday, Democratic Sen. Chuck Schumer of New York urged FAA officials to reevaluate training criteria for new pilots.

“Yesterday we found out that the pilot of Flight 3407 was not properly trained to use certain equipment that could have possible helped him save the flight from crashing,” Schumer said in a statement. “While it is impossible to eliminate all human error, proper training can help to minimize the risk.

The father of one of Flight 3407 victims said the hearings were "very difficult for the families" — but necessary to implement change in the future.

"The management of this airline clearly leaves a lot to be desired," Scott Maurer, father of passenger Lorin Maurer, told FOX News. "We've spent many hours this week walking the halls of Congress."

Click here for the entire docket for the NTSB hearings on the crash.

Click here for the schedule of the hearings and to watch them via live Webcast.

The Associated Press contributed to this report.