The air traffic control failure that disrupted transtasman flights at the weekend was caused by an issue with the cross-system transfer of flight information data, says Airways New Zealand’s boss.

New Zealand’s oceanic air traffic control system was disrupted by a technical fault in Airways’ main Operational Control System (OCS) platform on Saturday night.

The fault closed oceanic airspace, forcing five Australia-bound flights to circle off New Zealand’s coast, and delaying planes in both countries.

Airways chief executive James Young, who apologised to affected passengers and promised a full technical review into the incident, told Herald NOW’s Ryan Bridge that the transfer of flight information data from one system to another “was not working as it should”.

This led air traffic controllers to restrict traffic flows over an extended period.

“It looks like it’s a system issue, and it’s linked into the transfer of the data.

A flight to Brisbane circled off the coast before being diverted back to Wellington Airport on Saturday. Photo / Flightradar24

“I don’t have much more to say about it at this point and that is the subject of the investigation.”

Young said the back-up system kicked in almost immediately, but Airways staff had to conduct data checks to ensure all flight plans were correctly loaded into the new system.

“We activated that process at about 4.30pm.”

Work to repair the fault on the primary system began at the same time.

“As it turned out, the primary system was stood back up fairly quickly - after about 25 minutes - and then we [went] through our normal process to return it to service again.”

Young said the system is designed so that “if there is a failure at one point, we normally have another system that we can fail over to - which is what we were working through at the time”.

Airways New Zealand has promised a "full technical review" into the system outage. Photo / Brett Phibbs

Airways had acknowledged and apologised to affected airlines for the disruption caused, but there have been no further discussions around compensation for the fault.

“That’s a conversation that we would have to have at some point down the track, but that is not normal.

“It’s a very complex system, the aviation system. There’s lots of different parts. At this stage, that’s not a consideration.”

Young assured passengers there was no safety risk at the time, as this was managed by maintaining verbal communications with, and visual sight of, aircraft.

Air traffic control outage ‘very rare’, says aviation expert
“Very rare” was how aviation expert Mike Haines described the traffic control failure.

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, told the Herald 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.

“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.”

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