An investigation has been launched after a mayday call was received this morning, possibly from a plane flying near the Waimakariri Gorge in Canterbury.
Two helicopters were scrambled by Rescue Coordination Centre (RCCNZ) after the mercy message was received on an aviation channel, but no signs of a downed aircraft were found.
An RCCNZ spokesman said a plane flying over the gorge, west of Christchurch, heard the call at 11.20am and notified air traffic controller Airways New Zealand, which told RCCNZ.
Garden City Helicopters pilot Neil Scott said two choppers had flown up the gorge, parts of which were covered in snow.
The aircraft which heard the call had also joined the search, which covered some 1000 hectares.