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Fighting forest fires often has the image of helmeted Smokey Bear heading off into the woods with his shovel over his shoulder, digging hand guards and using fire hoses to put out a raging forest fire. These techniques are still a large and vital part of modern fire fighting but a look at the other side of the story shows they are only a part of the many actions needed to fight a large forest fire.

Fires are driven by three things: oxygen, fuel, and heat. Simple in concept, these elements become increasingly complex in their interactions. The current Lonesome Lake fire in the West Chilcotin is a good case in point. The terrain there is as complex as it gets. From rugged boulder-strewn flats to cliff faces dropping 2000 feet sheer to the lakes below, the jumbled topography creates wind patterns that are unpredictable. The winds can blow one way for part of the day then shift in an instant to another direction. An up draft becomes a down draft. A cross wind becomes a down wind or an up wind. Wind speed is constantly changing in response to local heating, amount of cloud cover, heat generated by the fire front and things like ice fields. There are often inversions which separate the ground winds from the upper winds. When a column of heated air breaks through the inversion, it can suck the upper level air flow down to the ground and cause mixing and an increase in wind speed. All of this puts more oxygen the fire. These interactions are studied by the weather specialists working the fire. They run computer models on an hourly basis to provide information to the fire crews on the ground.

The fuel loading, or burnable material, also determines the rate and extent of the fire spread. For ground fires, blow-down and the duff layer are the major components. More slow-moving, these ground fires are easier to control with the usual methods of fire breaks and hand guards where the material and the duff are removed down to mineral soil.

The terrifying crown fires are the ones that race through the canopy, throwing up columns of heat and smoke in mushroom clouds that can push up to 14,000 feet or more. Standing dead trees are not the real problem. It is the live evergreen trees with their needles full of resins and oils that explode into flame all at once. The sparks created by this ignition ride the air column, putting embers into the air which often land ahead of the fire, "spotting" new fires and causing the fire to leapfrog erratically across the landscape.

These crown fires are very dependent on tree type, density, and age. Old growth with dense crowns are the worst. These are the types that produce the walls of fire up to several hundred feet high which race across the land, unstoppable.

Heat is caused both by the fire itself and the usual heating caused by the sun as the day proceeds. Relative humidity is also important in the heat equation. In the morning, when humidity is higher, the fire is damped down somewhat because of the high heat absorption that the water vapour has. As the temperatures rise the humidity drops, making the heat levels rise and the fire more volatile.

These are the basics. The challenge is to put together a fire-fighting strategy that takes all of these factors into account on an hour by hour basis. It is like trying to walk across a gymnasium floor that is covered with marbles while trying to balance a glass of water on your nose. Balance the inputs, make a decision, monitor the action and then reassess.

To do all of this requires many different specialists. The ground initial-attack crews are highly trained professionals, used to working in dangerous conditions. Making fire breaks, assessing fuel loading, wind direction, fire speed and direction, these crews are always on high levels of alert while working under gruelling physical conditions of heat and smoke.

Just getting these crews on the ground is a huge task. Helicopter flights must be co-ordinated, smoke conditions determined, rate and spread of fire forecasted, drop areas built.

Helicopters are also used to lay in retardant lines of a fertilizer mix dyed an orange red colour so the pilots can see where the drop landed. Heavy water bombers also drop these lines which can stop the trees from burning. Effective in some situations such as small fire fronts, retardant lines are an important part of the arsenal.

Water can be bucketed up to put out small local hot spots. The larger helicopters called "heavies" can lift 1,000 gallons at time up to the fire sites. These methods are effective on a small scale but they cannot control the larger fire fronts.

The best way to approach large fires is fight fire with fight fire. Literally. This is a very tricky and dangerous business. The usual way is to get well ahead of the fire, build a guard using bulldozers, excavators and other heavy equipment. This guard is then used as a boundary from which to start a backfire. The idea is to burn the fuel ahead of the fire, creating a "blackline" which will stop the advance of the forest fire. Sometimes large areas of tens or hundreds of hectares are burned off to remove fuels. In some cases the backburn is designed so that it will burn to the fire front itself; other times, the backburn can be used to move the fire front in a different direction. The updraft from the backburn can cause a shift in the wind patterns to suck the fire into a new position.

Backburns are often hand lit on the ground by specialized crews that use drip torches to light the forest afire, a very risk-filled job indeed.

To cover larger areas, helicopters are used to start backfires but conditions have to be just right. Wind speed and direction, topography, fuels, and immediate forecasts are weighed and the decision is made. Two helicopters are deployed to the burn spot. One heavier machine has the drip line on board. The pilot hovers above the target spot and presses a release button which drops flaming gasoline/jet fuel mixture onto the ground.

Above and off the side of this helicopter is the bird-dog helicopter. He hovers just above the fire machine and gives directions as to where to move to next and how effective the burn is, all the while watching for freak winds, smoke eruptions and other factors which would influence the burn as well as the safety of the other helicopter.

To see these two machines moving in tandem against a black cloud of smoke, dripping yellow fire into the forest is like watching two huge dragonflies locked in a surrealistic mating ritual.

The resources needed to successfully accomplish these very sophisticated procedures are huge. To fight a fire of the size of the Lonesome Lake one, a small town of 500 hundred people is set up complete with everything from laundry, food services and sewage treatment to satellite communications which download the latest infrared imagery from satellite for accurately determining the position of the fire front often hidden from ordinary observation by heavy smoke.

Specialists in wildfire fighting are imperative. They must handle local and regional weather forecasting, flight coordination, crew logistics and operations, radio, telephone and computer networks, safety and security, and communications to the community and the media. These components must be carefully thought out and planned for. For example, getting the 6,000 litres of fuel that the air fleet uses each hour of air time delivered when and where it is needed is just one of the thousands of details that must dovetail with everything else in order to make modern fire-fighting the effective machine that it is.

Smokey may still need his spade and bucket, but they are just part of the complex system that has evolved to fight wildfire in the forest.