The air traffic control system outage that disrupted flights to and from New Zealand yesterday was “very rare” but is not symptomatic of a wider system issue, an aviation expert with 30-plus years of industry experience says.
A “technical fault” in Airways New Zealand’s main Operational Control System (OCS) platform caused disruptions to New Zealand’s oceanic air traffic control system last night, the Civil Aviation Authority (CAA) said.
The fault closed oceanic airspace and forced five transtasman flights to circle off New Zealand’s coast.
Airways – the entity responsible for New Zealand’s air traffic control system – apologised to affected passengers last night, with chief executive James Young promising a “full technical review” into the incident.
Asked whether it was yet clear what prompted the outage, Young told the Herald today the cause was “still being investigated”.
Mike Haines, who worked as the CAA’s former aeronautical services manager for seven years and as Airways’ former head of policy and standards from 2014 until 2019, said he expects Airways’ internal investigation into the incident will be “robust” and monitored by the CAA.
New Zealand’s air traffic control system is “one of the more modern and comprehensive systems” worldwide, Haines said.
Failures were rare, given there are already “multiple systems and redundancy processes” in place.
“At each stage of service reduction, safety is ensured and different procedures for air traffic control and aircraft separation apply,” Haines said.
He didn’t believe passengers were in any danger during yesterday’s outage as the correct processes appeared to have been initiated.
“What does occur is reduction in airspace capacity – that is, limiting flights into the airspace, increasing distance and height spacing between aircraft, and not accepting aircraft into the airspace.
“Not accepting aircraft is a procedure to ensure that air traffic control can still meet the safety criteria and while they assess the system issue, they reduce aircraft in the airspace.”
Young confirmed this procedure was used when Airways switched to its back-up system, prohibiting new flight paths – essential for maintaining safe aircraft separation – from being processed.
“Aircraft still flying in our domestic airspace sectors were held in the air and those on the ground did not depart.”
Haines said delays like those stemming from the system failure are “precautionary and are to ensure the safety of the flight first”, noting that the transtasman route “is a busy airspace”.
“Additionally, aircraft have on-board systems to allow them to communicate with other aircraft nearby and alerting systems in the aircraft if the separation is reduced.”
It was impossible to speculate on the cause without knowing more “as the air traffic control system is rather complex and with multi-layer redundancy”, Haines said.
“It may have been a minor issue but was treated as a major issue until they could get assurance of what occurred and what systems are in place.
“This is supported by the short duration of disruption.”
In a statement on its website, Young, the Airways CEO, said an issue with its main oceanic air traffic control system “temporarily disrupted” transtasman air traffic services yesterday.
“At 4.30pm, the main oceanic air traffic control system experienced an outage and operations were switched to a back-up system. During this time, flight plans for the Tasman sector were unable to be processed through the system, causing delays.
“As a result of this, five flights were held in the air, three of which were diverted back to New Zealand after holding for around 40 minutes, with the remaining two flights proceeding to their destination after holding. Flights were also held on the ground in both Australia and New Zealand during this time.”
Several flights were either cancelled or delayed as a result.
In a follow-up statement, Young told the Herald Airways’ “top priority” is ensuring aircraft can safely operate in the skies.
“Disruption to our systems is uncommon, however it is something we plan for and have back-up systems in place to allow us to maintain safety in this type of event.”
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