Hopes are quickly fading in the search for missing AirAsia flight QZ8501, with a search chief revealing the plane is most likely “at the bottom of the sea”.

One-hundred-and-sixty-two people are on board the plane according to the passenger manifest.

“Based on the coordinates given to us and evaluation that the estimated crash position is in the sea, the hypothesis is the plane is at the bottom of the sea,” National Search and Rescue Agency chief Bambang Soelistyo told a press conference.

“That’s the preliminary suspicion and it can develop based on the evaluation of the result of our search.”

• Search for missing AirAsia jet halted for day
• Passengers’ relatives await news of missing plane

The search for the flight that disappeared in bad weather over the Java Sea resumed on Monday morning after being halted due to fading light on Sunday night.

As the widespread search continued, Jakarta’s Air Force base commander Rear Marshal Dwi Putranto said an Australian Orion aircraft had detected suspicious objects near Nangka island, about 160 kilometres southwest of Pangkalan Bun, near central Kalimantan, or 1120 kilometres from the location where the plane lost contact.

The objects were later determined not to be from the AirAsia plane, Indonesian Vice President Jusuf Kalla said.

“It has been checked and no sufficient evidence was found to confirm what was reported,” Mr Kalla told a press conference at Surabaya airport from where the ill-fated plane departed.

An RAAF P3 Orion maritime patrol aircraft left from Darwin early on Monday morning to join the search, Defence said in a statement.

Defence Force boss Air Chief Marshal Mark Binskin said the Orion had well-proven search and rescue capabilities.

An RAAF P3 Orion has been sent to assist in the search. Photo: AAP

It has a maritime search radar along with infra-red and electro-optical sensors to help the crew with their visual scans of the ocean.

Foreign Minister Julie Bishop says Australia is ready to contribute further to international efforts to find the missing plane.

She says, however, hopes are fading of finding the plane and the passengers on board.

“Whilst we hope for the best, as time goes on I’m afraid our fears may be confirmed,” Ms Bishop told ABC TV on Monday.

“Our thoughts and prayers and hopes are with the passengers and the crew and our thoughts are most certainly with their families and relatives.”

Ms Bishop has been in touch with her Indonesian counterpart.

Overnight, Prime Minister Tony Abbott called Indonesian president Joko Widodo to offer assistance.

Air traffic controllers lost contact with the twin-engine aircraft about an hour after it left Juanda international airport at Surabaya in East Java at 5.20am local time.

It was scheduled to arrive in Singapore at 8.30am local time but went missing in bad weather.

The government in Jakarta said it did not “dare to presume what [had] happened” to the aircraft.

There were no Australian citizens on board, but authorities are still checking the flight manifest for any dual nationals or permanent residents.

[jwplayer player=”1″ mediaid=”185615″]