The crew aboard a Delta jetliner that skidded off a LaGuardia Airport runway last week told federal investigators the plane did not seem to slow down even though the auto brake switch in the cockpit was set to "max."
Complicating the landing, as well, was the failure of the automatic spoilers -- plates on the top of the wings that help slow the aircraft during landings -- to deploy, said the National Transportation Safety Board.
The first officer "quickly" deployed them manually, the NTSB said in its most recent update released Monday.
Investigators interviewed the five-member crew over the weekend in Atlanta as part of the probe into what caused Thursday's crash.
"The captain reported that he was unable to prevent the airplane from drifting left," the NTSB said, adding that investigators continue to test the aircraft's antiskid, auto brake and thrust reverser systems.
The electronic signals that activate the auto brakes and spoiler come from the same device, said John Goglia, an independent air safety consultant and former NTSB board member not involved in the investigation.
"That's telling us there may have been a problem in the circuitry," Goglia said.
Delta Air Lines Flight 1086, an MD-88 carrying 127 passengers and five crew, took off from Hartsfield-Jackson Atlanta International Airport shortly after 9 a.m. The plane careened off the runway at 11:28 a.m., the NTSB said, while landing during a snowstorm, plowing through an earthen berm and stopping just short of plunging into Flushing Bay.
There were 28 people injured. Several passengers taken to hospitals for evaluation have been released, the agency said.
The runway had been plowed just minutes before Delta Flight 1086 touched down, and two other pilots who landed on the same runway reported "good braking actions," the Port Authority, the airport operator, said last week. Air traffic controllers at LaGuardia relayed the pilots' braking action reports to the flight crew of Delta Flight 1086.
About three minutes before Delta Flight 1086 touched down on Runway 13, one of those other planes -- an MD-88 aircraft -- landed on the same runway, according to the NTSB.
When the Delta plane descended through the clouds, the runway "appeared all white," the crew told investigators.
Monday, the NTSB released more details of when and how the plane skidded off Runway 13, which is 7,000 feet long.
After it touched down, the aircraft began to veer off at about 3,000 feet down the runway. At about 4,100 feet, the plane's left wing struck the perimeter fence, which is located on top of the berm. The plane came to rest with its nose hanging over the icy waters.
"The left wing of the airplane destroyed about 940 feet of the perimeter fence," according to the NTSB.
There was significant damage to the airplane, including to the fuel tank, nose landing gear and the underside of the fuselage from the front of the airplane to the area of the left front passenger door.
Investigators reviewed the plane's maintenance records on Saturday and so far have learned that the last major maintenance occurred Sept. 22 in Jacksonville, Florida, and included tests of the auto brake, antiskid and auto spoiler systems. The last overnight service check was completed March 2 in Tampa, Florida.
At the time of the accident, the aircraft had 71,195 flight hours and 54,865 flight cycles, according to the NTSB.
A preliminary review of the flight data recorder, or "black box," found that airspeed during the final approach was about 140 knots and 133 knots at the time it touched down on the runway, which Goglia said meant the pilot was not speeding.
An NTSB meteorologist is reviewing weather conditions at the time of the accident and a group of investigators is scheduled to gather Tuesday at the agency's headquarters in Washington, D.C., to begin transcribing the cockpit voice recorder.