A thrust reverser on the plane which crashed in Brazil, killing some 200 people, had been deactivated during maintenance checks, the airline says.
The reversers can be used to help jets slow down on landing but Tam Airlines insisted the deactivation was in accordance with proper procedures.
The Tam Airlines' Airbus 320 overshot the runway at Sao Paulo's Congonhas airport, hit buildings and exploded.
There has been intense speculation but no confirmation on the crash's cause.
But the crash has brought mounting calls for Congonhas airport to close.
Brazilian President Luis Inacio Lula da Silva, who has been criticised by opponents for his low profile since the crash, will address the nation on Friday and is expected to announce new measures on air safety.
Tam Airlines said the right thrust reverser was "deactivated" at the time of the accident "in conditions stipulated by the maintenance of the manufacturer Airbus and approved by [Brazil's] National Civil Aviation Agency".
Tam Airlines' comments came after Brazil's Globo TV said a problem with the right thrust reverser had emerged four days before the crash.
Tam said Airbus's own manual says an inspection can be done up to 10 days after it is first detected and that the plane can continue to operate in the meantime.
Globo TV also reported that the same plane had problems landing at Congonhas the day before the crash.
The channel said the plane only managed to stop at the limit of the runway. The pilot told air traffic controllers it was very slippery but did not mention any other problems, the report said.
The crash occurred in wet conditions on a recently resurfaced runway that has been criticised as being too short.
New video footage shows some of the final moments of the Tam Airlines flight from the southern city of Porto Alegre, and another similar plane that had arrived earlier.
It appears to show the Tam plane travelling along one section of the runway at higher than normal speed.
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It shows the first aircraft apparently taking 11 seconds to travel along the visible section, while the plane that crashed covers the same distance in three.
The Airbus 320 jet appears to continue speeding along the runway without slowing, before disappearing out of view. The flash of an explosion can be seen a short time later.
According to Globo TV, the Brazilian air force, which oversees the country's air traffic control system, believes the footage shows the plane was travelling at excessive speed.
As the plane careered towards the busy road nearby, one theory is that the pilot tried to take off again. The aircraft crossed the road and ploughed into a Tam Airlines building.
"That he jumped over the avenue was an indication he tried to take off. If he didn't [try to take off] he would have gone nose down at the end of the runway," Brig Jorge Kersul Filho, director of the Air Force's Centre for Investigation and Prevention of Air Accidents, said.
Some 180 bodies have been recovered from the burnt wreckage, says fire chief Nilton Miranda, adding another 20 bodies are expected to be found.
Most of the passengers and crew on board the flight were Brazilian.