Air traffic services outage, 30 September 2019
Status
Closed
Occurrence Date
Report Publication Date
Jurisdiction
NZ
What happened
On 30 September 2019, at approximately 1320 , Airways Corporation of New Zealand Limited’s (Airways) air traffic services were unexpectedly disrupted for 47 minutes (the outage).
For the duration of the outage the Christchurch domestic controllers lost processed radar surveillance target information from their control screens. The system automatically reverted to a degraded display mode that allowed controllers to continue to monitor aircraft positions. The outage also affected their primary communication method with aircraft pilots and other sector controllers requiring them to switch to their backup communication systems. The Auckland controllers also lost the use of their surveillance control screens for a shorter period, until they switched over to local bypass surveillance information.
At the time of the outage 41 domestic flights were airborne in New Zealand controlled airspace. All aircraft landed safely, with no airspace separation issues.
Why it happened
The outage was initiated by a capacitor failure in an uninterruptible power supply (UPS) unit in the Christchurch air traffic management centre. This failure alone should not have caused a loss of air traffic management services. However, incorrect power connections from the UPS to the core digital network equipment supporting the air traffic management services caused some of that equipment to also lose power. That 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. If they had been, Airways would very likely have discovered the incorrect power connections and prevented this outage.
What we can learn
Safety-critical equipment should be stress tested to ensure it is resilient to power supply interruption.
Who may benefit
This report will benefit air traffic management centres, and anyone required to maintain electrical equipment that performs essential safety functions.
On 30 September 2019, at approximately 1320 , Airways Corporation of New Zealand Limited’s (Airways) air traffic services were unexpectedly disrupted for 47 minutes (the outage).
For the duration of the outage the Christchurch domestic controllers lost processed radar surveillance target information from their control screens. The system automatically reverted to a degraded display mode that allowed controllers to continue to monitor aircraft positions. The outage also affected their primary communication method with aircraft pilots and other sector controllers requiring them to switch to their backup communication systems. The Auckland controllers also lost the use of their surveillance control screens for a shorter period, until they switched over to local bypass surveillance information.
At the time of the outage 41 domestic flights were airborne in New Zealand controlled airspace. All aircraft landed safely, with no airspace separation issues.
Why it happened
The outage was initiated by a capacitor failure in an uninterruptible power supply (UPS) unit in the Christchurch air traffic management centre. This failure alone should not have caused a loss of air traffic management services. However, incorrect power connections from the UPS to the core digital network equipment supporting the air traffic management services caused some of that equipment to also lose power. That 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. If they had been, Airways would very likely have discovered the incorrect power connections and prevented this outage.
What we can learn
Safety-critical equipment should be stress tested to ensure it is resilient to power supply interruption.
Who may benefit
This report will benefit air traffic management centres, and anyone required to maintain electrical equipment that performs essential safety functions.
Location
Christchurch (-43.487906,172.532859) [may be approximate]