The plane was flying from Auckland's North Shore to Te Kuiti when it went missing.
Air traffic controllers last heard from the lone pilot at 6.50pm when he reported his location over Raglan, estimating he would reach New Plymouth about an hour later.
At 7.30pm the Rescue Coordination Centre (RCC) received a beacon distress signal from the Cessna 152.
RCC tracked the beacon to a spot on land, 35km west of Te Kuiti.
Air Force spokesman Squadron Leader Kavae Tamariki said the weather conditions were still bad this morning, with heavy rain and strong winds.
He said the Iroquois helicopter took off from Ohakea last night.
"We'll do whatever we can to assist the operation," Mr Tamariki said earlier this morning.
RCC spokeswoman Sarah Brazil said a team of three specialist alpine searchers were sent to the site.
She said the police had set up a base at Waikawau, only 6km from the beacon signal.
Last night a helicopter was dispatched from Hamilton but could not get low enough to search the area because of cloud. After refuelling the crew tried again but the weather had worsened and the flight was abandoned.
Another Air Force Iroquois helicopter from Ohakea joined the search but encountered the same problems and is now on the ground in New Plymouth.
A search party is expected to head into the steep terrain at sunrise.
The missing pilot was a member of the New Plymouth aero club and was believed to hold a commercial licence and be completing instructor training.
- NZ HERALD STAFF & NZPA
