Wellington City Council admits a new tsunami warning system needs a bit of work, after some people were panicked.
The council received 50 phone calls about test exercises on Wednesday evening which left some residents thinking the city was facing a real emergency.
A new tsunami and civil defence warning system was tested from 6pm to 7pm on Wednesday.
Vehicles and a low-flying helicopter broadcast advisory messages and a siren through powerful loudspeakers.
Despite a warning that it was a test, Civil Defence controller Mike Mendonca says blustery conditions meant the sound quality from the helicopter was not clear enough.
He says the technical issues will be ironed out and the system will be tested again in a few months.