Authorities Hopeful About Finding AirAsia Jet

Search planes and ships from several countries on Monday were scouring Indonesian waters over which an AirAsia jet carrying 162 people disappeared, and more than a day into the region’s latest aviation mystery, officials doubted there could be anything but a tragic ending.

AirAsia Flight 8501 vanished Sunday in airspace thick with storm clouds on its way from Surabaya, Indonesia, to Singapore. The search expanded Monday, but has yet to find any trace of the Airbus A320.

‘‘Based on the coordinates that we know, the evaluation would be that any estimated crash position is in the sea, and that the hypothesis is the plane is at the bottom of the sea,’’ Indonesia search and rescue chief Henry Bambang Soelistyo said at a news conference.

First Adm. Sigit Setiayana, the Naval Aviation Center commander at the Surabaya air force base, said 12 navy ships, five planes, three helicopters and a number of warships were taking part in the search, along with ships and planes from Singapore and Malaysia. The Australian Air Force also sent a search plane.

The plane’s disappearance and suspected crash caps an astonishingly tragic year for air travel in Southeast Asia. The Malaysia-based carrier’s loss comes on top of the still-unexplained disappearance of Malaysia Airlines Flight 370 in March and the downing of Malaysia Airlines Flight 17 in July over Ukraine.