The Taupo-based Greenlea Rescue helicopter was also used on Friday morning to search forestry and farmland adjacent to Bonshaw Park.
Despite the many hours of searching, there is still no sign of him.
"Searchers have experienced challenging weather conditions, terrain and vegetation in the area around Bonshaw Park, and our concern for Mr Pritchard's safety continues to grow," Senior Constable Barry Shepherd of Taupo Police said.
"We thank the local residents, and friends and family of Mr Pritchard who have been looking for him, and encourage others in the area to keep their eyes out,"
Anyone with information which could help find Pritchard, especially those who live at, work around, or who have visited Bonshaw Park on Thursday morning between 9.15 and 10am, are asked to contact police.