Indonesia's safety agency is set to search the waters today for the 62 people aboard a Sriwijaya Air Boeing 737 that went missing shortly after take-off from the capital Jakarta yesterday.
Flight SJ182's last contact was at around 2.40pm Jakarta time, four minutes into its 90-minute journey to Pontianak, capital of West Kalimantan province.
Carrying 12 crew and 50 passengers, including seven children and three infants, the aircraft lost more than 3,000m in altitude in less than a minute, according to flight-tracking website Flightradar24.
All on board were Indonesian nationals.
Several witnesses living on an island near where the plane disappeared described hearing explosions, while others believed they had found objects that were from the plane.
"We heard a big boom around 2pm," a resident of Lancang island, part of the Thousand Islands district north of Jakarta, told Jakarta-based Elshinta radio. "We all first thought it was thunder because rain was pouring."
Indonesia's search and rescue agency Basarnas said at a press briefing last night that the focus of this morning's search is between Laki island and Lancang island, about 11 nautical miles from where the plane took off.
"Our personnel have reached the coordinates where the plane crashed," National Transportation Safety Committee head Soerjanto Tjahjono said.
"We will do a survey to determine (what) the condition at the location is. We will deploy... underwater recovery equipment."
Basarnas deputy chief, Major-General Bambang Suyo Aji, said: "Search operations will continue 24 hours a day, focusing on the area where debris probably belonging to the plane was found."
Basarnas has not received a distress signal transmitted from the plane's emergency locator transmitter.
Transport Ministry spokesman Adita Irawati said the plane had deviated from its normal course and gone in a north-west direction.
Seconds after air traffic controllers asked the pilots about the reason for the deviation, the plane disappeared from the radar.
Sriwijaya Air chief executive Jefferson Irwin Jauwena told reporters that the flight was delayed due to heavy rain. The plane was supposed to take off about an hour earlier.
According to its registration details, the plane is a 26-year-old Boeing 737-500 that first flew in 1994.
Sriwijaya Air, a private budget airline which flies to Indonesian destinations and to China, Malaysia and Timor-Leste, was established in 2003.
Eighteen out of 30 Sriwijaya Air planes were grounded by the Transport Ministry in September 2019 over airworthiness concerns.
Indonesia's aviation sector has long suffered from a patchy air safety record, and its airlines were once banned from entering US and European airspace.
Yesterday, distraught relatives waited in Pontianak.
Mr Yaman Zai, a father of three children who were aboard the plane with their mother, told Reuters that he was at the airport in Pontianak waiting for them when he heard the news.
"I will never meet her again," he said, holding a photo of his oldest daughter.