Taupo rescue helicopter chief pilot John Funnell said his son and Mr Shepherd went up in a fixed-wing plane on Monday and yesterday his son and Mr Bond went up in a helicopter.
They launched their search from Fishing Rock, where the man had gone missing.
"We'll be searching all the little islands, the coastal lines and rocky outcrops to see if we can find the missing party."
It was hoped the helicopter would start searching about 6.30pm yesterday and would search for the remaining 90 minutes of daylight and resume the mission this morning if necessary.
"The weather is not too bad up there. There is a big sea running. We are hopeful that he may have been washed on to one of the other islands but it's a long shot," John Funnell told The Daily Post last night.
He did not know who the volunteer was.
John Funnell and Mr Shepherd were part of the Taupo rescue team of five that made a mercy dash to save five Department of Conservation workers trapped on Raoul Island in 2006 following a volcanic eruption. A sixth worker, Mark Kearney, 33, disappeared while doing a routine check of the water temperature in the island's crater lake and his body was never found.
DoC spokeswoman Liz Maire yesterday afternoon said the probability of the volunteer being found was "quite slim".
The Rescue Co-ordination Centre said it considered the search an active search and rescue operation.
Ms Maire said the three workers and three volunteers remaining on the island would do all they could to find their workmate.
"Understandably they've been very emotionally involved. It's not easy to cope with an incident like this, where there's lots of unanswered questions," she told APNZ. The man had been on Raoul Island, about 1000km northeast of Auckland and renowned for volcanic eruptions and almost daily earthquakes, since October on a six-month stint of duty.
He was one of four volunteers helping three DoC staff, who monitor seismic and volcanic activity as well as conduct conservation work such as eradicating weeds to protect the more than 100 plants which are native to the Kermadecs.
They are the only people on the island, which is a tightly-controlled nature reserve.
The missing man's family had been notified, as well as the relatives of other workers on the island. Additional reporting by APNZ