The helicopters respectively belong to the National Search and Rescue Agency (Basarnas), PT Jafpa, and the Indonesian police, Riyadil Akhir, head of the North Sumatra disaster mitigation office, stated here, Tuesday.
Eight days after the search efforts, the SAR teams managed to rescue 21 survivors and found three bodies of passengers of the ill-fated boat.
MV Sinar Bangun sank in Lake Toba on June 18 when it was carrying over 190 passengers and crew members.
Lake Toba is the world`s deepest volcanic lake having a depth of 900 meters and spanning a surface area of 1,145 square kilometers. It is a popular tourist destination in North Sumatra.
Scan sonar has detected objects in two locations at a depth of 490 meters in Lake Toba in North Sumatra on Sunday evening, Chief of Basarnas M. Syaugi noted.
"We still have to analyze the objects further, but we have marked the locations," he noted at the Tiga Ras Port in Simalungun District, North Sumatra, on Sunday.
The objects are detected two kilometers and 2.5 kilometers southwest of the port respectively, he remarked.
Basarnas will ascertain the objects at the two locations before taking further steps, he revealed.
He further praised the local people for their initiative to help search for the victims.
According to the standard operating procedure, after the search has lasted for seven days, it could be extended for another three days. If the time has passed by, and no indicator is found, it can be extended again.