His nephew's parents and other immediate family were in Nelson waiting for news.
"Like every family in a situation like this everybody is waiting and wondering and worrying like hell because we don't know anything.
"It's just wait and wait and wait and hope to hell they can find him."
The searchers were "doing their utmost" to find his nephew, Mr Webster said.
"But it's still difficult - we're just feeling helpless and waiting."
He described his nephew as a "great, great guy".
"He'll do anything for anybody. He's a nice young guy."
The missing helicopter had a tracking device and searchers had narrowed their focus to an area 35km west of Motueka.
However, the terrain was steep and covered in dense bush.
"It's a waiting game and it's frustrating and difficult because they seem to have it narrowed down to a fairly small area where he should be, but they just can't quite find him."
It was important his nephew was found, Mr Webster said.
"We can't change what might have happened to him at this stage, but we just want him to be found - that's the most important thing for everybody."
The Rescue Coordination Centre New Zealand said no sign of the helicopter had been found after another day of searching.
Four helicopters and five ground crews would search until dusk, spokesman Steve Rendle said.
The weather conditions had remained calm for the day.
The aircraft was believed to belong to Helicopter Charter Karamea.
Co-owner Julie Pratt declined to comment about the incident.
Two helicopters left Karamea about 8am Monday to fly to Nelson. The pilot of the second helicopter raised the alarm about noon that day when Damian Webster failed to arrive in Nelson.
Rescue Coordination Centre New Zealand (RCCNZ) search and rescue controller Neville Blakemore said all options were being considered in planning the search.
"After consideration of alternative routes taken through the area in the past, we had two ground teams working along another valley and over a saddle which could have been on the route taken," he said.
"Overnight we'll be reviewing all elements of the search to date and assessing the best approach to take tomorrow."
The area being searched is about 5km in each direction from the last signal received.
Today, based on analysis of routes taken on previous flights between Karamea and Nelson, a new area of focus was added within the same broad area.
