MH370 Underwater Search Areas Planning Map
MH370 Underwater Search Areas Planning MapAustralia Transport Safety Bureau

Malaysia Airlines Flight MH370 is "very likely" to be found in the Indian Ocean despite being submerged for more than 10 months, the Australian authorities have said.

Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, which is leading the search for the missing Boeing 777 along the so-called seventh arc in the Indian Ocean also said it was probably "in a good condition".

"Our satellite calculations gave us an area we determined was high priority," Dolan told AFP. "In this 60,000 square kilometres (about 23,166 square miles), it's very likely we will find the aircraft, but we don't know exactly where. We just have to cover that area thoroughly."

So far, one quarter of the priority underwater search area has been checked, while a wider zone of 208,000 square kilometres has been mapped.

Dolan added: "It's just that it's a very large area, so it's going to take a long time."

Search ships are using sophisticated sonar systems to trace the airliner and has deployed the new Fugro Supporter vessel.

"(It) can be programmed and cover areas much more thoroughly. It's of course a lot slower," Dolan said. "We need to go slow so that we can be 100 percent sure that we have covered that area totally."

239 people lost their lives on board when it disappeared on March 8 last year.