Underwater robot, airborne drones aid cave search

MAE SAI, Chiang Rai: A remotely operated underwater vehicle and two airborne drones equipped with heat detectors were deployed to search for 12 teenage footballers and a coach stranded three nights deep inside sprawling caverns cut off by rising water.

Sawangtit Srikitsuwan, head of a joint team from the Air Force disaster prevention unit and the Centre of Excellence for Astronautical and Marine Engineering, said the underwater vehicle would feed data about the condition and depth of the cave before divers entered.

The vehicle was previously used to survey marine natural resources and has never been used in a rescue operation, the marine engineering expert said. The drones equipped with heat detectors would survey areas outside the cave to support the rescue operation.

Somsak Khanakham, chief of Mae Sai district, said rescue teams were racing against time to find the 13 missing people. The Seals were the main rescue team, he said, with other teams from a border patrol police unit and the national park surveying the area on foot to find an alternate entrance into the caverns. Deputy Prime Minister and Defence Minister Prawit Wongsuwon said local authorities may drill into the mountain if necessary.

Paithoon Nakthae, director of the disaster prevention and mitigation office, said divers from Sweden joined local Thai divers to search for the missing people as the rescue operation entered the fourth day.

The water level inside the cave rose to almost 7 metres after rainfall on Tuesday morning. Thongplew Kongchan, director-general of the Irrigation Departgment, said more water pumps would be installed to pump out water from the flooded cave.

Theerapong Bureerak, director of Chiang Mai-based provincial electricity regional office 1, said local electricians worked until 1am on Tuesday to extend a power line into the flooded cave for a distance of 900 metres in order to provide light and ventilation and help divers communicate with those outside. The line would be extended to 3 kilometres today as rescue teams resumed the search for the missing boys and their coach, Thai media reported.

Navy Lt Naponwath Homsai said the divers will enter the water after they reach a chamber farther inside that was flooded almost to its ceiling on Monday. “We hope that the water level has gone down but we will have to see. Today we will try to find passages which are under the water that hopefully will lead to other chambers.”

The sprawling cave complex extends several kilometres and has wide chambers and narrow passageways with rocky outcrops and changes in elevation. Still, officials have said they are hopeful the boys found a safe space away from the floods.

The boys, aged 11-16, and their 25-year-old coach were believed to have entered the Tham Luang Nang Non cave in Chiang Rai province late Saturday afternoon. A mother reported that her son did not return from football practice that day, setting off the search.

Rising waters Monday evening frustrated efforts to search farther in the cave, and the efforts were halted temporarily. During the night, rescue teams and electricians extended a power line 1 kilometre into the cave.

“We hope this would provide lights for work and fans for ventilation for the Seal team,” Chiang Rai Gov Narongsak Osottanakorn said. “Also, it means we can use electric engines to pump water out from the cave as well.”

Parents waited overnight in tents outside the cave entrance as rain poured. Medics sat in a tent nearby, and the bicycles, backpacks and football cleats the boys left behind remained at the entrance.

Lt Naponwath said late Monday that other shoes and bags belonging to the group had been left in a cave chamber, and “We believe the students have gone further in.”

Tuesday morning, relatives and others performed a ritual calling for those who are missing. They played drums and gongs and two relatives held fishing nets as symbols to fish out lost spirits from the cave. Organiser Jiratat Kodyee said the ritual was a traditional way of showing support for the boys' families.

At a prayer session the previous evening, some relatives walked inside the cave entrance, where their cries echoed off the walls. “My son, come on out! I am waiting for you here!” one woman cried. Another kneeled down near the bicycles and prayed, asking “Where is my child?”

Namhom Boonpiam, whose 13-year-old son Mongkol is among the missing, said she had been waiting at the entrance since Saturday night.

“I haven't slept and I hope that all of them can come out, all safe and sound,” she said. “My son is a strong boy. I still have hope.”

Authorities have said footprints and handprints were found inside the cave complex, and that tourists trapped there by past floods have been rescued after the waters receded.

Officials are hopeful there are still safe spaces in the cave complex despite the flooding, Chiang Rai Deputy Governor Passakorn Bunyalak told a news conference.

“We're confident that the kids should still be in good condition,” he said, noting that rescuers had seen nothing inside the cave to indicate otherwise.

Getting farther into the cave has required lots of oxygen and special diving skills, which would also complicate rescue efforts once the boys are found, Mr Passakorn said. He said divers might have to first bring in food and the boys might need to wait out the flood or learn the basics of scuba to get out.

The cave, cut into a mountainside near the border with Myanmar, can flood severely during the rainy season, which runs from June to October.

In “The Caves of Northern Thailand,” an online guidebook updated this year, the cave is described as explorable only from November to June due to flooding. It says the cave is an easy walk at first, but farther inside, finding a route through the rock formations and narrow passages can be difficult.

Earlier reports:

• Rising water obstructs search of trapped students, coach 
• Divers enter flooded cave in search of missing students
• 12 feared trapped in Mae Sai cave