From an earlier post..
French businessman Jean Grandy, 49, one of four foreigners on the plane, said that the flight from the city of Bandung in West Java had appeared to be landing smoothly.
"The final approach was fine," he told AFP.
"Then suddenly, a cloud enveloped us. Torrents of water were pouring on us, it was an enormous downpour. It only lasted two, three minutes.
"It was almost as if it was night, even though the sun had been shining just before," said Grandy.
Two or three mins and dark? Sounds like a pretty large lump in the sky. Photos suggest visibility was otherwise quite good. Wonder why they didn't see it ahead of them?