Smoking radar facility UPS halts NZ flights

New Zealand's national air traffic system suffered a serious fault today that led departing flights within the country's airspace being halted.

State-owned enterprise Airways, which manages New Zeealand's air traffic systems, said the fault was caused by a fire alarm being set off by smoke from one of its uninterruptible power supplies that had failed.

The fault occured at approximately 1.20 pm New Zealand time at the Airways' Andy Herd Building in Christchurch that houses its main radar facility.

Airways said the fire alarm led to its radar and communications systems reverting to back-up system mode.

Airways chief executive Graeme Sumner apologised for the travel delays caused by the smoke from the UPS.

Sumner said that 36 flights were delayed and three had to turn around and land again while the system was in back-up mode.

Domestic airborne traffic continued to be safely managed, ditto airborne international flights that were unaffected as Airways' Oceanic control centre operates independently from Auckland.

Normal operations resumed at 2.15 pm NZDST with systems running normally on mains power supply with back-up again, allowing domestic flights to depart again.

AIrways did not say how many flights were delayed by the fault, or how many passengers were affected by it.

In June 2015, a two-hour radar nationwide outage following an internal network failure at Airways saw air traffic controllers forced to guide airborne flights by radio.