Federal investigators are examining whether pilot error or an aircraft malfunction led to last week's near-disaster at LaGuardia Airport when a Delta Air Lines jet skidded off a runway during a snowstorm, Sen. Charles Schumer said Sunday.

"There are four possible areas where something went wrong," said Schumer (D-N.Y.), who received an update Sunday on the National Transportation Safety Board investigation into the skidding accident on Thursday.

Schumer said investigators are looking at whether the accident was caused by the pilot, who may have been going too fast; whether there was a malfunction to the airplane's thrust reversers, which may have caused the airplane to skid to one side; whether the braking rules at the airport were "inadequate;" or whether ice played a factor.

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Delta Flight 1086, traveling from Atlanta, was carrying 127 passengers and five crew members when it plowed through a berm, broke a chain-link perimeter fence and slid to a stop with its nose hanging over Flushing Bay. Twenty-eight people were hurt, but none of the injuries were life-threatening, officials said.

NTSB spokesman Terry Williams declined to comment yesterday in an email, but said the agency will have an update Monday or Tuesday that will "include information from the recorders, crew interviews and information from investigators in New York."

The NTSB said Friday the Boeing MD-88 jet's cockpit voice and flight data recorders had been downloaded.

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Schumer said ice on the runway will probably be ruled out because "two planes had landed safely" before the skidding accident and the runway also had been freshly plowed.

Schumer said investigators are still decoding the aircraft's recording device that will help determine what caused the accident.

With Nicole Fuller