An Indonesian official confirmed Wednesday that divers and an unmanned underwater vehicle had spotted the tail of missing AirAsia Flight 8501 in the Java Sea.

The find is particularly important because the cockpit voice and flight data recorders, or black boxes, are located in the aircraft's tail. It is the first confirmed sighting of any wreckage 10 days after the plane disappeared en route to Singapore from Surabaya, Indonesia with 162 passengers on board. Small pieces of the plane, such as seats, have previously been spotted.

Strong currents had forced search and rescue operations to expand the search area for debris, bodies, and suspected chunks of the plane's fuselage on the ocean floor. National Search and Rescue chief Henry Bambang Soelistyo told reporters that the tail was identified from a photograph of the debris taken by searchers. One released image appears to show an upside down "A" painted on a piece of metal, while another grainy shot depicted some sort of mechanical parts.

The debris is located about 6 miles from where Flight 8501 lost contact with air traffic controllers Dec. 28 and was originally detected by an Indonesian survey ship. 

Soelistyo said the top priority remains recovering more bodies along with the black boxes. So far, 40 corpses have been found, including an additional one announced Wednesday, but time is running out.

At two weeks, most corpses will sink, said Anton Castilani, head of the country's disaster identification victim unit, and there are already signs of serious decomposition.

The Airbus A320 went down Dec. 28, halfway through a two-hour flight, killing everyone on board. It is not clear what caused the crash, but bad weather is believed to be a contributing factor.

Just before losing contact, the pilot told air traffic control he was approaching threatening clouds, but was denied permission to climb to a higher altitude because of heavy air traffic. No distress signal was issued.

Finding the black boxes will be key to the investigation. They provide essential information including the plane's vertical and horizontal speeds along with engine temperature and final conversations between the captain and co-pilot. The ping-emitting beacons still have about 20 days before their batteries go dead, but high surf had prevented the deployment of ships that drag "ping" locators.

Ships equipped with sonar devices have also identified what they believe to be the fuselage of the plane. Several other big chunks have been found, the largest measuring 46 by 13 feet, though they have not yet received visual confirmation.

In addition to heavy rain and wind, the monsoon weather has turned the Java Sea into a slush bowl.

But in some ways, it is one of the best places to look for a missing plane, especially when compared to the extreme depths of the Indian Ocean where searchers continue to hunt for Malaysia Airlines Flight 370, which disappeared last March with 239 people aboard.

The water at the Indonesia site is shallow, but this is the worst time of the year for a recovery operation to take place due to seasonal rains that have created choppy seas and blinding mud and silt from river runoff.

"Because the Java Sea is such an enclosed basin, and there's not really big currents passing through it, everything just stays there for quite a while and the waves make it so that the sediment doesn't slowly just sink to the bottom," said Erik van Sebille, an oceanographer at the University of New South Wales in Sydney, Australia. "It continuously keeps churning it up."

He said the conditions also make it particularly dangerous for divers because the water is dark and murky, making it easy for them to cut themselves on jagged wreckage or even become snared and trapped. During the dry season, he added, it would likely be easy to see the plane underwater from the sky.

The Associated Press contributed to this report.