Anatomy of a

The fires in Tasman are so vast it’s difficult to imagine just how the brave firefighting crews on the frontline go about extinguishing them. Just where do you start?

John Sutton has been putting out fires for almost 50 years. These days he’s at the strategic end of the spectrum as rural Fire and Emergency New Zealand regional manager.

It is he and his team who are responsible for co-ordinating the crew on the ground. It’s hot, unpredictable and tense work. And it’s not letting up.

The environment of a fire can change in a millisecond from something that’s reasonably safe to something that’s absolutely life-threatening.

The fire is smaller than earlier assessed – 1600 hectares with a 23-kilometre perimeter – but the wind is up, the sun is out and the fire is vulnerable to growth.

Here, Sutton describes the anatomy of a firefight.

The safety of the firefighting crew always come first when making the call on how and where to battle the flames, he says. Communities come second and infrastructure third.

All the strategic decisions are made at the Incident Control Point, a headquarters where about 40 people right now are making decisions on where crews will fight the fires, depending on crucial information gleaned from myriad sources. The battle to put out the fires is plotted and planned in excruciating detail.

Almost everything the firefighters are doing on the ground has been orchestrated from this point.

There are imperative factors to consider, says Sutton.

The geography of the land, and the extent and nature of the potential fuel in its path, such as grass, forest land and buildings, and accessibility of the land around the perimeter of the fire, are all taken into account. But perhaps the most important element to consider is the weather.

When assessing how to fight the fire, the weather is a doozy.

‘‘The temperature, the wind and the amount of humidity will play a big part in the intensity and the heat of the fire,’’ Sutton says.

‘‘Wednesday was dream firefighting weather – overcast, high in humidity, low winds.

‘‘The wind has since picked up and the humidity has dropped. Friday looks set to be windy, and we are worried.’’

The team get online support from the Metservice with up-tothe-minute forecasts available. They have weather stations within the perimeter of the fire, so local weather recordings give them the exact wind speed and direction, humidity and temperature accessed at the touch of a button on their phones. These give them a better idea where to fight the fire from.

The lie of the land will influence how a fire is fought, says Sutton.

The Nelson fires are in undulating land as well as along a ridge line. Fires spread faster uphill and, when you get wind and a slope, you’re in trouble.

Aircraft are used to assess the fire’s reach and establish the perimeter.

‘‘Wherever the fire burns to becomes the boundary, and we try to hold it there, extinguishing any heat along the edge. Initially the fire was burning so fast and so hot no-one could get near enough to attempt to put it out it.’’

Once firefighters have gone 30 metres in to the scorched earth from the perimeter, that band becomes the containment line. When crews have achieved that 100 per cent they consider that containment, even if it’s still burning beyond it. get smoke and embers, but it can also be subterranean.

You get a bit of wind and heat and it can suddenly flare up from under the ground, Sutton warns.

Sixteen helicopters, more than a dozen ground firefighting crews, and three aircraft just aren’t enough to get the fires under control. So Sutton’s team have enlisted the help of 20 crew using heavy machinery to put in strategically placed firebreaks in places they anticipate fire creep.

They can’t do the whole 23km perimeter in a day, so they instead focus on the highpriority areas.

In places they can’t get the heavy machinery, they are using ground crew to put in chemical firebreaks. The chemical is a fire retardant that, when exposed to heat, will extinguish the fire.

This is applied with three fixed-wing aircraft. Co-ordinators have resorted to digging water holes in river beds for the helicopters to fill their monsoon buckets. They are also sourcing water from temporary reservoirs set up around the perimeter. Water is trucked into these reservoirs by tankers.

Firefighters use foam where they can because it helps the water penetrate the ground and minimises access of oxygen to