Air traffic services in Christchurch and Auckland were affected by power outages in 2019. Photo: RNZ / Nate McKinnon
An investigation has found air traffic control could have avoided temporarily losing radar surveillance in a 2019 incident if the equipment had been tested and maintained properly.
Airways air traffic services partially lost power causing a radar surveillance outage for 47 minutes in Christchurch and for a shorter time in Auckland when 41 domestic flights were airborne in September 2019.
The Transport Accident Investigation Commission said air traffic control managed to cope with back-ups and all aircraft landed safely and without issues.
That included reverting to a degraded display mode so controllers could continue to monitor aircraft positions and switching to back-up communication between pilots and controllers.
The outage was initiated when a capacitor exploded in an uninterruptible power supply unit in the Christchurch air traffic management centre.
The commission found that this failure alone should not have caused the service loss.
Instead, the power connections between the unit and the core digital network equipment were incorrectly wired, which caused some of that equipment to also lose power.
That equipment supports air traffic management services and the power loss caused the outage.
"The commission found maintenance checks had not been conducted on the core digital network equipment in accordance with Airways' procedures," the report said.
"If they had been, Airways would very likely have discovered the incorrect power connections and prevented this outage."
The commission recommended safety-critical equipment should be stress-tested to ensure it remained resilient to power supply interruption.