His body was recovered earlier this afternoon not far from the incident.
Siti Kuzaimah Annuar (surveyor) and Henry Lay (engineer) were also killed in the crash.
The pilot of the helicopter Reco Steger, 35, a german, survived the crash.
The helicopter is owned by local businessman Sng Chee Hua.
They were on their way to Nanga Merit, Kapit to inspect a project when the incident occurred.
Ato, an engineer and contractor, was being groomed to contest the Mambong seat in the coming general election.
In the state election last year, he did pretty well against Roland Sagah of Pesaka Bumiputera Bersatu (PBB) party in the Tarat constituency, which is part of Mambong parliamentary constituency.
He polled 4,292 votes as against 6,287 votes secured by Sagah.
This is the second death involving PKR leaders.
Last April Sharkawi Nahri was killed in a road accident at Bukit Begunan. He was earmarked to contest the Batang Sadong constituency against the incumbent Nancy Shukri.
Ato’s remains are now at the Kuching mortuary pending a postmortem.
Ato leaves behind wife Agnes Batang and three children, a son aged 25, and two daughters, aged 20 and 18.