Telstra owns and operates the largest and most diverse subsea cable network in Asia Pacific – a region where internet data consumption grew by 70 per cent last year alone. But it’s also a region that presents a number of hazards to this subsea network.

Combatting some of these challenges is a dedicated team of experts at Telstra’s Network Operations Centres (NOC) in Hong Kong and Singapore who work in partnership with the Marine Operations team. This group of subsea cable experts and technical specialists are responsible for protecting our subsea cables and the services that run across the Telstra network, in addition to organising repairs in the event a cable gets damaged.

The NOC tools: AIS and ROV

A ship’s Automatic Identification System (AIS) provides information such as its unique identification number, position, course, and speed. Similar to air traffic controllers, the team at the NOC use the AIS data to monitor the location of ships entering and leaving the busy, shallow ports of Hong Kong and Singapore. If a ship gets too close to one of Telstra’s cables, the NOC team will make a call to the captain so they can adjust their course. On average, the Singapore team contacts 30 to 50 large vessels a month.

This tracking has helped to reduce the damage caused by ships cutting cables around Hong Kong and Singapore’s ports by 50 per cent since 2013, which translates to better network availability for customers.

So what happens when a cable is damaged?

The NOC and Marine Operations teams will perform an initial assessment to locate the position of the fault and determine the impact on services. Once this is done they will try to minimise customer impacts by redirecting network traffic to other cables if possible and assess whether a full scale maintenance ship needs to be sent to the site to undertake repair work.

If the cable needs to be repaired, the team will organise one of the cable maintenance ships on standby in Taiwan to get to the site. These ships have remotely operated vehicles (ROVs) on board, which play an important role when it comes to locating cable damage and speeding up the repair process.

These machines can either visually detect where the cable damage is, or if visibility is bad, they can do an ‘echo’ test which picks up signals emitted by the cable. ROVs can go to a depth of up to 3,000 metres – the maximum depth a diver can reach is 304 metres.

Once the damage is located, special equipment such as a grapnel hook is needed to grab and retrieve the damaged section of cable and bring it to the surface for onboarding and repair. This is because cables are far too heavy to be lifted by an ROV or repaired whilst underwater beyond the depth a diver can reach.

If a damaged cable is off the coast of Singapore, it takes around eight days for the maintenance ship to travel down from Taiwan, an average of seven to 10 days for the repair work, and another eight days to make the trip back to its station in Taiwan. The number of days to repair the cable can vary depending on the extent of the damage and how deep the water is. At significant depths, for example, it can take around 15 to 18 hours just to lower the grapnel hook to the seabed to begin retrieving the damaged cable, and the same amount of time to raise it back up to the surface.

In contrast to the incredible speed and immediacy of the internet, monitoring and maintaining a subsea cable network can often be laborious and resource-intensive. But at the NOC, we take pride in the fact that our work sustains the very backbone of the internet. Through smart cable design, timely fault detection, and experienced people working tirelessly to fix cable damage, we ensure fast and consistent connection so that millions across Asia Pacific can work, shop, socialise and entertain themselves online.

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