Investigators examining multiple plane crashes this year have their hands full, but today they announced that ice was not likely the cause of last month's fatal plane crash near Buffalo, N.Y., despite early media reports identifying ice as a potential culprit.
In reducing the emphasis on ice as a major cause of the crash, investigators are examining the role the pilot may have played in the accident. New flight data recorder information released today reveals that the controls of the plane were pulled back, which affected the aerodynamics of the wing.
The National Transportation Safety Board said it would continue to look at the pilot's experience and training in connection with the Feb. 12 crash that killed 50 people.
The NTSB said that while there was some ice present, "the airplane continued to respond as expected to flight control inputs throughout the accident flight."
The safety board added that "Preliminary airplane performance modeling and simulation efforts indicate that icing had a minimal impact on the stall speed of the airplane."
Fifty people died when the Continental Express commuter plane crashed a few miles short of the runway.
ABC News learned in mid-February that the pilot on the Buffalo flight may have put the plane into its deadly plunge.
A source close to the investigation said information from the flight data recorder indicated that the pilot's control column, essentially the device used to steer the plane, moved sharply backward, pitching the nose of the turboprop upward.
Investigators said they were surprised a pilot would take that action and wanted to make sure there wasn't some other explanation for the movement of the plane's controls.
Federal investigators said today that when the stick was pulled back, the airflow, or lift, over the top of the wing was likely lost. Losing lift over a wing can cause an aircraft to stall.
"If you think you're stalling, you don't pull, you push," ABC News' aviation consultant John Nance said in mid-February.
It can be exceedingly difficult to recover from a stall like the one experienced in the Buffalo crash and, in this case, the crew had only 1,600 to 1,800 feet to do so before the plane hit the ground.
Shortly after the crash, investigators said they were also looking carefully at the training the pilot received, as they do with any accident. The captain, Marvin Renslow, 47, was new to the Canadian-made Bombardier Dash 8 Q400, with 110 hours at the controls flying passengers.
On Feb. 18, Colgan Air, which operated the flight for Continental, defended the pilot's experience and stressed confidence in its operations.
"Capt. Renslow had 3,379 total hours of flight experience and was Airline Transport Pilot rated, which is the highest level of certification available," read a statement from Colgan Air, which operated the flight for Continental Feb. 18. "That rating, combined with 172 hours of formal training on the Q400 aircraft, qualified him fully in accordance with all applicable federal aviation regulations."
Investigators also said today they have reviewed airplane maintenance records and have not uncovered any "significant findings." Toxicology reports also found no alcohol or illicit drugs in the flight crew.
NTSB Also Busy With Weekend Crash
The NTSB is also investigating last weekend's crash of a private plane in Montana, which also occurred just short of the runway. Fourteen people, including seven children, died Sunday when a Pilatus PC-12 crashed into a cemetery 500 feet from the Bert Mooney Airport in Butte, Mont.
NTSB investigators issued updates Monday and Tuesday on the incident before turning their focus today to last month's crash near Buffalo.
In both disasters, there were initial reports of conditions conducive to icing at lower elevations and reports from witnesses that the planes appeared to dive into the ground.
In the Butte crash, investigators have also been examiningwhether weight distribution and balance on the overloaded plane played a part. They also want to know why the Swiss-made, single-engine turboprop diverted to Butte instead of continuing on to its intended destination in nearby Bozeman, Mont. Without a cockpit voice recorder or flight data recorder to provide important clues about what happened, the investigation is expected to take some time.
ABC News reported Tuesday that 12 days before the fatal crash, the Federal Aviation Administration issued an airworthiness directive on the plane, requiring that a safety inspection be performed to check for a problem that could reduce the effectiveness of the plane's controls.
The safety inspections were not yet required, but the directive was scheduled to take effect March 30. The plane's manufacturer had also sent out a service bulletin in January about potential problems.
In the Butte crash, the pilot, Ellison Summerfield, was an experienced former Air Force pilot who was well known in Southern California's Inland Empire aviation community. He had logged more than 2,000 flying hours on that plane.