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Helicopter Logging

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Forestry Processes
A helicopter equipped with a tagline for logging.
Helicopter logging or heli-logging involves using helicopters in the forest harvesting of trees. According to the Helicopter Association International, there are about 175 companies operating worldwide that use helicopters to remove timber.[1] Most of these companies offer their heli-logging services to contractors and licensees that have been given the right to extract timber from government land or federal timber reserves.

In B.C. and the Pacific Northwest, heli-logging has become a common way to remove high value, unharvestable timber—such as red cedar—not able to be harvested by conventional logging methods. The cut block may be situated on terrain that is steep and hilly like a gully or riparian, susceptible to soil erosion, or too remote for roads to lead to. Another advantage is that heli-logging leaves a lighter ecological foot print than ground-based logging because disturbance on the ground is greatly minimized as logs are not being yarded or skidded to the landing site.

There are currently two types of heli-logging. Conventional heli-logging involves lifting and transporting individual trees or small groups of trees bundled together and lifted with a sky hook located underneath the helicopter to a landing site. A newer method, called "single stem" or "standing stem" harvesting, involves marking a tree ahead of time and then removing it using a horizontal grapple. The grapple, attached by a cable or tagline to the helicopter, is used to grab and snap the trunk of the tree at a pre-cut point. The stem of the tree is then lifted into the air by the helicopter and delivered directly to a landing site or released into water.

Contents

[edit] History

Interest in using helicopters for logging started as early as the 1950s and '60s in countries such as Norway, Scotland, and Canada.[2] The first helicopters used were not equipped with sufficient lift ability to facilitate the removal of heavy logs. In the 1970s, helicopter logging evolved into a more practical alternative when heavy-lifting helicopters were developed for military purposes in Vietnam.[3]

[edit] Process

[edit] Conventional Heli-logging

Conventional heli-logging involves felling trees in the traditional way and then lifting them individually or bundling them up into loads using a sky hook hanging from underneath the helicopter. Conventional logging accommodates many felling methods including shelterwood, patch cut, selective, and clear cut methods. The logs are flown to a landing site where they get loaded onto a log truck and taken to a mill or sorting facility. It can also be used in combination with mechanical harvesting equipment such as feller bunchers.

A heli-logging operation usually involves a ground crew to retrieve chokers and rigging. The helicopter is equipped with a hanging cable called a tagline. Located at the bottom of the tagline is an electrically activated hook. As the helicopter flies in to pick up a load of trees, the hook is attached to the chokesetter and then connected to a prechoked bundle of wood. The ground crew vacates the area to permit the helicopter to safely lift the load of wood off the ground. The load is flown to a landing area and dropped; the helicopter then returns to the cut block to pick up another load. The process, referred to a "cycle," takes a matter of minutes. While the helicopter is transporting a load of trees to the landing, the ground crew is retrieving the chokers and rigging gear.

[edit] Standing Stem Heli-logging

Standing stem heli-logging is fairly new to the forestry scene and involves more detailed preparation in the removal of trees. In this form of heli-logging, quality of timber takes precedence over quantity. It is also more expensive than conventional heli-logging because trees are marked in advance and the helicopter extracts each tree individually, leaving much of the surrounding landscape still intact. In this manner, standing stem heli-logging offers a variable retention approach to a cut block.

There are typically four stages involved in the operation. The first stage is engineering—the selection of each tree. The size of the tree is one factor to be considered. The bigger the tree, the more cost-effective its removal becomes. Another factor is the value of the timber. Trees removed in standing stem heli-logging must be of high value to justify the cost of such an operation. A number and a marker, usually a colored ribbon, indicate which trees have been selected for harvesting. The tree will also be measured according to its diameter at breast height (DBH).[4] This measurement allows the engineer to determine at what height the tree should be topped. All this information gets put on a map to assist the jiggers, climbers, and helicopter crew.

The second phase of the operation involves climbing. A ground crew supports a crew of four to five climbers wearing climbing spurs, who ascend the tree from ground level. As they climb, they delimb the tree branch by branch using specialized chainsaws. Each climber is also outfitted with a special harness equipped with a wire rope that encircles the entire tree, with both ends attached to the climber. The climber will reach a specified height, top the tree, and then repel back down again to the ground. The tree is then ready for jigging.

The third phase, jigging, is the actual felling of the tree. Jigging must be completed by a professionally certified faller, or by a faller trainer under the supervision of a certified faller as it is very dangerous work. The faller uses a tool called a jigging table to help calculate how much of the tree should be left standing to so that the helicopter is able to break the tree at the stump.

The final phase of the process is flying the wood out of the forest. A helicopter pilot and crew use the information provided on the map to identify the marked tree on the ground. The trees, once prepared, are called "stems." The trees get lifted from the forest floor using a horizontal grapple connected to a cable that is attached to the underside of the helicopter. The trees located at the lowest elevation within a cut block are taken out first. Lighter-weight trees also get removed first, when the helicopter is carrying more weight in fuel; heavier trees are removed as the fuel level decreases. Since heli-logging is so expensive, the average time a helicopter will stay in the air lifting trees and making drops is about an hour and a half. The lift and drop of a tree is often referred to as a "turn." The more turns a helicopter achieves within a given timeframe, the more cost-effective the operation becomes. A turn can last anywhere from 20 seconds to one minute.[5]

It is also required that pilots in a helicopter logging operation have previous flying experience—about 1,000 to 1,500 flight hours. They will often train first as a co-pilot, having 2,500 to 3,000 flight hours under their belt before getting trained as a logging pilot.[6]

[edit] The Downside of Heli-logging

One of the biggest drawbacks of heli-logging is the cost. At $5,000 per hour—about $100 per minute—time is of the essence.[7] When things go wrong, it literally translates into thousands of dollars lost. That is why preparation and an organized ground crew are essential in keeping the flow of a heli-logging operation moving. In some operations, for example, chokers are preset on the ground by workers called "chasers" to create quicker turns for the helicopter. The chasers also work at the drop point to retrieve the chokers and rigging gear from the helicopter after it unloads a tree or bundle of trees. Operational costs are often offset by using a smaller helicopter to run errands or even fly chokers back into the woods, as using a larger helicopter such as a Skycrane is just too expensive.

Another drawback is the apparent safety hazards associated with heli-logging. Aside from the dangers common in felling, adding a helicopter to the mix introduces additional risks. For example, the rotor wash—wind—generated by the helicopter can exceed speeds of 62 miles (100 km) per hour.[8] This means that any loose debris such as limbs, snags, or non-wind-safe trees have to be cleared before a tree can be flown out of the cutblock. A dropped load is also another risk. The helicopter has to stick to a marked route making sure not cross the path of the crew working on the ground.

[edit] Equipment Used

[edit] References

  1. Helicopter Logging's Bumpy Ride. Timberwest. July-Aug 2003. 05-03-2009.
  2. Aerial Logging Systems. Forest Encyclopedia Network. 05-03-2009.
  3. RHelicopter Logging's Bumpy Ride. Timberwest. July-Aug 2003. 05-03-2009.
  4. Heli-logging's High-end Niche. Helicopters Magazine. 05-03-2009.
  5. Helicopter Logging. Vannattabros. 05-03-2009.
  6. Heli-logging's High-end Niche. Helicopters Magazine. 05-03-2009.
  7. Helicopter Logging. Vannattabros. 05-03-2009.
  8. Logging's Bumpy Ride. Timberwest. July-Aug 2003. 05-03-2009.

[edit] External Links