Australian Naval Operations Accidentally Jam New Zealand’s Internet and Radio

Residents and businesses across New Zealand’s North and South Islands experienced an unexpected and widespread interruption to wireless internet and radio services.

The cause was traced to HMAS Canberra, the Royal Australian Navy’s largest warship, as it navigated the Cook Strait en route to Wellington.

The ship’s advanced navigation radar system, operating in the 5 GHz band, inadvertently interfered with wireless access points and radio transmitters in regions including Taranaki and Marlborough.

The incident was not a routine outage.

Rather, it was a dramatic example of how military and civilian spectrum uses can collide in real-world scenarios.

The radar’s powerful signals, sweeping across coastal areas as the ship moved, triggered built-in safety mechanisms in 5 GHz wireless devices.

These mechanisms, part of the Dynamic Frequency Selection (DFS) protocol, are designed to detect and avoid radar signals to prevent interference with critical airspace and navigation systems.

How Radar and WiFi Collide

The 5 GHz band is a shared spectrum, used globally for unlicensed WiFi (IEEE 802.11a/n/ac/ax), as well as for radar systems such as those employed by military and meteorological services.

In New Zealand, rural and regional broadband providers heavily rely on fixed wireless broadband (FWB) solutions that operate within this band.

When HMAS Canberra’s navigation radar swept the area, its signals were detected by WiFi access points equipped with DFS.

Upon detecting radar pulses, DFS-enabled devices initiate a Channel Availability Check (CAC) and, if radar is confirmed, quickly switch to another channel.

This process, while intended to protect airspace, can result in temporary network outages as devices reboot or seek alternative frequencies.

In this case, the military-grade radar was so powerful and persistent that it effectively forced multiple access points offline across large geographic areas.

Matthew Harrison, managing director of ISP Primo, described the event: “DFS hits firing off all down the coastal area of Taranaki as the ship’s radar swept the area… We’ve never seen anything like it here before.

It was full-scale, military-grade radar triggering built-in safety protocols designed to protect airspace.”Other ISPs, including Inspire Net Limited and TPNet NZ, also reported outages.

Industry and Government Response:

The incident has sparked a broader conversation about the resilience and allocation of radio spectrum in New Zealand.

ISPs and industry experts have long advocated for increased access to spectrum, particularly in rural and regional areas where fixed wireless broadband is a critical service.

The shared nature of the 5 GHz band means that civilian networks are vulnerable to interference from powerful signals such as those emitted by military or aviation radar.

Craig Young, chief executive of the Telecommunications Users Association, noted that while the outage was resolved quickly once the source was identified, it highlighted a systemic weakness: “We do have a weakness in the current way that radio spectrum… can be overridden by a stronger signal in an area where this frequency can be used by other users.”

Sam James, a technical manager at TPNet, added: “The equipment behaved exactly as it’s designed to—it’s just that a visiting warship doesn’t normally show up in the spectrum plan.”

He called for a serious conversation about spectrum access and infrastructure resilience to prevent similar incidents in the future.

The Australian Defence Force acknowledged the incident and, upon notification, instructed HMAS Canberra to change its radar frequency, restoring normal service.

New Zealand’s Communications Minister and Defence Minister have both committed to reviewing the incident and exploring options to improve spectrum management and coordination with visiting military vessels.

Spectrum Allocation and Outage Impact

A Wake-Up Call for Spectrum Resilience

The HMAS Canberra incident has underscored the fragility of New Zealand’s radio spectrum environment, particularly for rural and regional communities dependent on fixed wireless broadband.

While the technical protocols functioned as designed, the event has prompted calls for more robust spectrum management and the release of additional frequency bands to reduce the risk of future disruptions.

As ISPs and government officials review the incident, the focus will be on ensuring that critical communications infrastructure is resilient in the face of both routine and unexpected challenges.

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