An Air New Zealand flight from Christchurch to Invercargill was forced to land in Dunedin when detectors indicated smoke on board.
Five fire appliances were sent to Dunedin Airport just after 8.30pm on Thursday to wait for Air New Zealand flight NZ8077 to land.
The airline says equipment on the plane had detected smoke in the cargo hold, but an examination failed to find anything.
Air New Zealand says engineers are inspecting the smoke indicator light. The plane was carrying 54 passengers.