PANGKALAN BUN, Indonesia - A 44-year-old fisherman is hailed by Indonesian media as the key to the multinational search operation for the doomed Indonesia AirAsia flight QZ8501.

The man, identified only as Rahmat, had stopped his boat at Senggora Island, south of the town of Pangkalan Bun in Central Kalimantan, on Sunday as it had been raining continuously since dawn, news website Detik.com reported on Wednesday.

Air traffic controllers had lost contact with flight QZ8501 only shortly before that, during the plane's journey from Indonesia's second-largest city of Surabaya to Singapore.

"Around 7am, I heard a loud booming sound. Soon afterwards, there was haze that usually happened only during the dry season," Rahmat said at the Panglima Utar Port in Central Kalimantan on Wednesday, according to Detik.

He said it crossed his mind then: "Was there a plane crash?"

But two of his friends, also fishermen, dismissed the thought.

"Before the booming sound, my friends saw a plane from above Senggaro Island heading towards the sea. The plane was said to be flying relatively low but then disappeared," said the father of three.

As the rain eased, Rahmat went out to sea but could not catch any fish amid waves as high as two metres.

"The next day (Mon), I returned home. After watching news on the missing plane, I reported to the village head," said Rahmat, who lives in Kubu village in Central Kalimantan.

Based on his testimony, the search and rescue team combed the area labelled as Sector V and found pieces of AirAsia flight QZ8501 wreckage and bodies of the victims, said Detik.

National rescue agency Basarnas said the wreckage is located some 160km southwest of Pangkalan Bun.