The hunt for the Airbus Group NV A320 single-aisle jet is focused on Kumai Bay. Poor visibility could hamper the effort, Indonesia's Vice President Jusuf Kalla said. The waters in the area are generally shallow, with depths of no more than 60 meters (197 feet) and warm temperatures that make diving easier.

Flight 370

The first planes that reached the region where the AirAsia plane was last reported didn't find any signs of the missing aircraft, Sutono, a communication director at the Indonesian search and rescue agency, said today. Searchers focused on an oil spill seen 100 nautical miles off Belitung island, Hadi Tjahjono, spokesman for Indonesia's Airforce told reporters.

Objects spotted by one of the search planes later turned out to be unrelated to the aircraft, the Airforce said. The plane wasn't equipped with a satelite-based tracking system that is more routine on long-distance aircraft, according to Inmarsat Plc in London.

Shares of AirAsia dropped 8.5% in Kuala Lumpur trading, their biggest slide since 2011. While AirAsia is based in Sepang, Malaysia, it operates with subsidiaries and affiliates in different countries. The missing plane belonged to its Indonesian operations.

“We're devastated, but we don't know what's happened yet,” Chief Executive Officer Tony Fernandes said at a press conference in Surabaya yesterday.

'Golden Hour'

The AirAsia pilots didn't send a distress signal, drawing comparisons with Malaysian Airline System Bhd.'s Flight 370 that disappeared on March 8 en route to Beijing from Kuala Lumpur. No wreckage from that flight has been found in what's become the longest search for a passenger jet in modern aviation.

AirAsia QZ8501 was at 32,000 feet when the pilots requested to fly higher to avoid clouds, Indonesia's acting Air Transport Director Djoko Murjatmodjo said in Jakarta. Air traffic controllers didn't respond to the request before the plane disappeared off radar, National Transportation Safety Committee head Tatang Kurniadi said at a press conference.

Indonesia may complete the transcript of the conversation between the air traffic control and AirAsia pilot by tomorrow.

There were storms along AirAsia's flight path, Accuweather.com said on its website, citing its meteorologist Dave Samuhel. Storms are very active this time of year, Samuhel was cited as saying, with December and January the wettest period of the year in Indonesia.

Last Signal

The last signal from the plane was between the city of Pontianak on Borneo and the town of Tanjung Pandan on Belitung island. The search was initially concentrated around Belitung, Transport Minister Ignasius Jonan said earlier. Sulistyo said the search area had been widened to include the Karimata strait and land areas in western West Kalimantan.

Robert Mann, head of aviation consultant R.W. Mann & Co. in Port Washington, New York, said searchers missed crucial daylight hours because authorities in Indonesia took an hour and 38 minutes to classify the plane as missing.

“It's the golden hour in an accident scene; you only have so many daylight hours,” he said in a phone interview.

AirAsia had no fatal crashes in its history of more than a decade of operations. The A320 has built a reputation as a sturdy workhorse, with more than 6,000 A320 family aircraft in service to date with over 300 operators.

The plane that disappeared was delivered to AirAsia from the production line in October 2008. Powered by CFM 56-5B engines built by a joint venture of General Electric Co. and France's Safran SA, the aircraft had accumulated approximately 23,000 flight hours in some 13,600 flights, Airbus said on its website.

The A320 and the related A318, A319 and A321 have among the lowest accident rates of modern commercial aircraft, with a fatal crash in about 1 in every 7 million departures, according to a study published in August by Boeing Co. The last fatal accident involving an Airbus single-aisle plane was in 2010, when an A321 operated by Pakistani carrier Airblue crashed into rugged terrain in heavy rain, killing all 152 people on board.

–With assistance from Andrew Janes and Rieka Rahadiana in Jakarta, Kyunghee Park in Singapore, Andrea Rothman in Toulouse and Niluksi Koswanage and Liau Y-Sing in Kuala Lumpur.

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