The caption in one of the photos linked to in DaveReidUK's post says "it was not raining at the moment of the accident," implying that it might have been earlier (contaminated runway?).
It may not have had anything to do with this incident, but it should be acknowledged that Congonhas is a rather cramped facility in the middle of a vast urban jungle. It seems to have had more than its share of prangs, crashes and near-misses over the past few years.
That is some spectacular footage from the CCTV.
