Reports indicate that debris and oil patches have been spotted in the Sea of Java near where Air Asia 8501 disappeared.

Jakarta's Air Force base commander Rear Marshal Dwi Putranto said an Australian Orion aircraft had detected suspicious objects around 1,120km from the point of last contact.

An Indonesian helicopter also spotted two oily spots this afternoon close to where a group of Indonesian fishermen claimed to have heard a crash near the island of Pulau Nangka.  

Rear Marshal Dwi Putranto said the objects were spotted near Nangka island, about 160 kilometres south-west of Pangkalan Bun, near central Kalimantan.

But he added: 'We cannot be sure whether it is part of the missing AirAsia plane. We are now moving in that direction, which is in cloudy conditions.' 

Indonesia's vice-president, Jusuf Kalla, also said there is 'insufficient evidence' the objects were from the missing AirAsia plane. 

But bad weather has prevented examination and conclusive identification of the debris.  Meanwhile, an Indonesian official has speculated that the plane is “at the bottom of the seas.”

As they resumed the search for the missing AirAsia plane Monday morning, Indonesian authorities said they believe the commercial jet with 162 people on board already lies at the bottom of the sea.

Indonesia’s National Search and Rescue Agency chief Bambang Soelistyo at a press conference called it a “preliminary suspicion” based on last coordinates and the estimated crash position.

With storms expected for the next few days, there may be a considerable lag before the black box can be recovered.  Speculation abounds as to what may have caused the presumed crash, in additiona to the previously hypothesized wind shear tearing the plane apart.  The U.K. Daily Mail:

...aviation experts said the flight was flying 'about 160 km/h too slow' when it encountered bad weather conditions. 

Aviation expert Geoffrey Thomas spoke to several check captains and believes the pilot of QZ8501 encountered difficult weather conditions but flew too slow in his efforts to avoid it.

'The QZ8501 was flying too slow, about 100 knots which is about 160 km/h too slow. At that altitude that's exceedingly dangerous,' Mr Thomas said. 

'Pilots believe that the crew, in trying to avoid the thunderstorm by climbing, somehow have found themselves flying too slow and thus induced an aerodynamic stall similar to the circumstances of the loss of Air France AF447 to crash in 2009.'   

The Air France AF447 crashed into the Atlantic Ocean in 2009 while en route from Rio De Janeiro to Paris. 

'I have a radar plot which shows him at 36,000 feet and climbing at a speed of 353 knots, which is approximately 100 knots too slow ... if the radar return is correct, he appears to be going too slow for the altitude he is flying at,' Mr Thomas said. 

Mr Thomas said this should not happen in an A320, so it appears as though it was related to extreme weather conditions.

'He got caught in a massive updraft or something like that. Something's gone terribly wrong,' he said.

'Essentially the plane is flying too slow to the altitude and the thin air, and the wings won't support it at that speed and you get a stall, an aerodynamic stall.'

This is all speculation, at this point.  But AF 447 does offer a precedent.