The ridges and kloofs of the Western Cape mountains are reverberating to the thud of helicopter blades and howling chainsaws as environmentalists make war on alien trees. At the centre is the team at Helihack.
By Paul Ash
It is a calm Friday in early October in Cape Town. The local forecast is for moderate weather, “zero precipitation” and winds of 8km/h. Perfect flying weather, then, for cranking up the Bell 407 and slinging a load of living, breathing ectoplasm at the end of a 30m line onto a steep ridge. Once their feet are on the ground, the three humans unclip from their line, fire up the chainsaws and get to work cutting pine trees.
The Bell, meanwhile, returns to the temporary landing zone, down on a valley floor or up on a ridge, to hook up three more chainsaw-mountaineers and sling them to another ridge strewn with pine trees.
This is Helihack, an initiative aimed at clearing alien pine trees and silky hakea from the province’s mountains and kloofs. Meanwhile, they keep a sharp eye on the weather, which in this part of the world can change as fast as it takes to chop a couple of pine trees.
The Helihack teams, made up largely of volunteers, are used to operating this way. After nearly 10 years of working in some of the country’s steepest and inaccessible terrain, they have learned to work around the considerable vagaries of the Cape’s weather. The winter of 2023 has been especially tough, however, with locals saying it has been the most brutal winter in decades. After months of cold fronts and weeks of rain, winter’s last gasp came in September with a cut-off low that brought heavy rain and floods to swathes of the province, causing landslides and sweeping away bridges, leaving millions of rands’ worth of damage in its wake.
Now, in the lull before the southeasters begin to blow, Helihack is making use of all the good weather it can get, says the organisation’s founder Aleck McKirdy. “We were on Table Mountain on Friday, then the wind came up on Saturday,” he says. “We only managed to get back on the mountain two days later.” That day, the teams cleared pine trees from about 20ha of mountainside.
The Helihack project aims to restore biodiversity and boost water yields by eradicating invasive alien vegetation in the mountain catchment areas of the Western Cape. Two of the alien invaders – pines (Pinus pinaster) and silky hakea (Hakea sericea) – have over the centuries spread across the mountains, guzzling water and threatening the indigenous Cape Floral Kingdom as they go.
A submission to the International Climbing and Mountaineering Federation (UIAA) notes that the mountains of the Western Cape are one of the strategic water source areas (SWSAs) for surface water in South Africa. SWSAs cover some 8% of SA but supply 50% of the country’s mean annual runoff. Along with climate change, the unchecked spread of alien vegetation such as pines and wattles is the biggest threat to SA’s strategic water sources. Much of the growth, however, has taken place in hard-to-reach places – the deep, inaccessible kloofs and remote ridges of the Western Cape’s mountains. Helihack has implemented two strategies to combat the invaders, both using helicopters.
Tackling the pines involves the simple but expensive process of slinging people armed with chainsaws onto the steep and overgrown ridges and impenetrable kloofs. The cutters must be proficient rock climbers who are also handy with a chainsaw. Operations usually involve up to 18 people working in teams of three. “Three is the maximum number of people we can have on the strop,” says McKirdy. The strop is a standard helicopter lifting sling at the end of the 30m line attached to the helicopter.
The technique is as simple as it is adrenalising for the operators. There is no winching. The helicopter gets airborne from the LZ and, using vertical references along with instructions from the team leaders, slings the operators onto the ridge or into the kloof where they are due to work. “Often the pilots are leaning out of the window,” says McKirdy. “It’s a real skill. One concentration lapse and the people could be lumped onto terrain.”
While the operation is by definition a high-risk endeavour, sorties have gone smoothly since the project began in 2014. The only drama McKirdy can recall is a team being caught by bad weather which forced the team to spend an extra night on the mountain. “We’ve had to walk down once after being caught out by a massive northwester,” he says.
Most operations involve two nights’ camping in the field to maximise the amount of alien vegetation they can remove from any area which means they are prepared in case of needing spend extra time on the mountain. In those cases, the helicopter will also be used to sling in the camping gear and equipment.
Fighting the invasive silky hakea requires an entirely different operation. Instead of landing teams to cut the bush, it is destroyed by shooting fungus into affected areas with the simplest tool of all – a 12-gauge shotgun. The fungal spores – a local herbicide that kills only the hakea – is applied to steel shot which is then loaded into standard shotgun shells. The shells are kept in an ordinary fridge until they are needed.
When an area has been identified for clearing, a team is flown to the site by helicopter. While hovering over the area, the gunner will blast the hakea at close range with the steel shot. It sounds crude but it works, says McKirdy. “It’s very effective indeed,” he says. The only restriction is ensuring the shotgun shells are kept at no more than 6°C. “But any fridge will work,” he says. The anti-hakea flying is handled by aerial spraying experts Ross Aviation.
The bell toils
In the 10 years the project has been running, the Bell 407 has emerged as the helicopter of choice for the work. The four-blade, single-engine helicopter – a derivative of Bell’s stalwart 206 Long Ranger – has found widespread service all over the world as a utility helicopter, with more than 1,400 examples built since the prototype first flew in 1994. The helicopters are supplied by Lanseria-based Savannah Helicopters which bases a machine in the Western Cape for use in the clearing season.
Helihack has also occasionally used a B3 Squirrel (“a very nice machine”, says McKirdy) and once tried a Bell UH-1 Huey. The Huey was found to be unsuitable for work, says McKirdy, noting that the machine felt “ponderous” in the role. Its low skids meant it was also hard to find suitable spots where it could safely land, he adds. Early operations used skid landings but these were soon discontinued in favour of the strop carrying the teams and their gear. Using the strop allowed the helicopter to transport the teams to steeper ground where the pines typically grow.
Bang for the buck
At R350,000 per day, mostly for the hire of a helicopter and pilot, the operation does not come cheap. Still, says McKirdy, the numbers speak for themselves. While the vegetation density and the steepness of the terrain will determine how fast any particular area can be cleared, using helicopters means the teams can be moved around much faster. “Some of the sections are so steep it’s almost possible to move around,” he says.
The project has cost roughly R4.4m since it began in 2014 with most of the money being spent on helicopter and pilot hire and sundries such as fuel for the chainsaws. Funding has come mostly from organisations such as the Drakenstein Trust which has also funded studies on biocontrol. Operations have also been funded by the Mapula Trust – a local nonprofit dedicated to environmental protection – whose contributions are matched by the Fynbos Trust. The UK-based Treebeard Fund has also contributed to operations.
“We have funding for four more operations,” says McKirdy. With a weekend-long operation removing between 4,000 and 6,000 trees, that means as many as 24,000 pine trees will no longer be around to slake their thirst on SA’s fragile supplies of groundwater.
Back to the mountain
After the southeaster put a temporary stop to aerial operations on Table Mountain in early October, the teams managed to clear 670 trees in three days while working on foot. After getting back in the air days later, 1,300 trees were cleared in just 3.9 hours of flying time. That works out at around R120 per tree, says McKirdy. “People have said it’s a waste of money but it’s actually quite efficient,” he says, adding that some of the removed pines “were real monsters”. Once removed, the pines are gone for good. “As long as there is nothing green left standing when the clearing is finished, they will never grow back.”
It is now early afternoon and a tablecloth of cloud is forming over the mountain. There will be no Helihacking this weekend, says McKirdy. “We’ve been messed around by the weather. It looks like this is going to be the basis for the next few weeks. We’re going to have to play it as it goes.”
Pull quote: While the operation is by definition a high-risk endeavour, sorties have gone smoothly since the project began in 2014.
Pull quote: In the 10 years the project has been running, the Bell 407 has emerged as the helicopter of choice for the work.
Pull quote: At R350,000 per day, mostly for the hire of a helicopter and pilot, the operation does not come cheap.
Helihacking by the numbers
2014: Project start date
USD25,000: Average cost for two days’ work
4,000-5,000: Average number of trees removed in two days, depending on terrain
R5m: Project costs to date
3: Average number of missions per year
6: Largest number of missions in a single year (2021)
3,300m3, Amount of runoff water lost to alien plants per year
One-third: Amount of SA’s total runoff water that could be lost to alien vegetation if no action is taken