Rescuers searching for a missing pilot and his microlight plane will resume the search on Monday morning.
Geoff Smale, 86, a former Olympic sailor, is believed to have left North Shore Airfield about 11am on Saturday, and was due in Ashburton 4.5 hours later, but never arrived.
The Rescue Co-ordination Centre says six helicopters and a fixed wing aircraft searched a large area between the North Shore and Ashburton on Sunday but found no trace of the missing microlight plane.
A Rescue Co-ordination Centre spokesperson, Ross Henderson, says the latest radar data shows an aircraft that could be Mr Smale's moving from Cape Soucis in Tasman Bay down through the Rai Valley, north east of Nelson.
A locator beacon carried by Mr Smale has not been activated and he was also carrying a radar device and a cell phone, but attempts to contact him have been unsuccessful.
Mr Smale won the 1958 Prince of Wales Cup and represented New Zealand at the 1968 Olympics in Mexico.
The family is also the name behind the Smales Farm technology park on the North Shore.
Mr Smale is a fully licensed microlight pilot.
The home-built aircraft, a Dyn Aero, is thought to be one of only a few in the country. It is understood to be about 18 months old.