The high-tech echo sounder, introduced earlier today, device was effective in scanning the riverbed but failed to locate the bodies of the 16 engineering students from Hyderabad and a tour operator, officials said.
So far eight bodies have been recovered by the rescue personnel.
"We deployed Side-scan Sonar to capture pictures of the riverbed to locate the bodies and it showed good images of the riverbed but no bodies were traced," Jaideep Singh, commanding officer of the National Disaster Response Force (NDRF), said.
The advanced equipment is a specialised system for detecting objects on the seafloor or river bed and conducting hydrographic surveys with side scan and multi-beam sonar.
A 10-km stretch of Beas river from Pandoh Dam, upstream the river was scanned for the first time using the device without any results.
It was for the third day that intensive search in the river failed to locate more bodies. Most of the bodies recovered were either trapped between rocks and boulders or sunk in silt within a 3-km distance from the accident spot at Thalot on the Chandigarh-Manali National Highway 21.
As many as 24 students, and a tour operator, of a group from Hyderabad's VNR Vignana Jyothi Institute of Engineering and Technology, who were on an excursion to Manali, were swept away in the river after sudden release of water from the reservoir of the Larji hydro-power project near Thalot.
Telangana Home Minister Nayani Narasimha Reddy, who has been camping here for the past six days, said, "We can now go in for the possibility of opening the gates of the Pandoh Dam to drastically reduce the water level in the reservoir to facilitate sighting of the bodies. However, any decision in this regard will be taken with the consent of the parents."
Opening the gates of Pandoh Dam is a tricky option as some of the parents of the missing students have expressed apprehension that the bodies might be washed away with the release of water and go downstream.
The district administration yesterday sought the consent of the parents and family of the missing students, who are camping here since Monday, to allow the administration to open the floodgates of the dam so that the bodies, if stuck in the reservoir, could be fished out.
"We can easily trace the bodies, if they are further washed away, with the release of water from the dam, as the river stretch is narrow downwards," Deputy Commissioner Devesh Kumar, who is coordinating the search operation, said.
About 600 rescue workers, comprising around 50 divers of the NDRF, the Army, the Navy and the ITBP, are involved in the joint search operation on 15-km long stretch of Beas river downstream Thalot.
State Industries Minister Mukesh Agnihotri, who visited the spot to take stock of the search and rescue operations met N Narsimha Reddy, Home Minister of Telangana, and parents of the engineering students at Pandoh Dam site and expressed his deep sympathies over the tragedy.
Agnihotri said the state government was making every possible effort to trace the bodies of missing students.