There are so many different ways to put out so many different types of fire. For our sake we’ll discuss the general techniques behind wildland fire attacks. You’ve probably heard a lot of fires over the radio and know the lingo, but now we can put that lingo into action and you can better understand what’s happening over the scanner.
Wildland fires get big with wind, fuel, and terrain. Where the fire starts is the origin of the fire. Once it starts the winds will push it in one direction. There are common terms used by all departments to describe each part of the fire and they resemble parts of the body (see diagram). The head of the fire is the active fire that is being pushed by the wind. Back where the origin is, usually opposite of the head is the heel of the fire. There is minimal burning since the wind is forcing the flames to “creep” into the already burned area. Left and right are determined by standing at the heel of the fire and looking out towards the head of the fire. Left and right are to the observer’s left and right.
The left and right flanks are the sides of the fire. There is usually active flame here but it is much lower than the flames at the head of the fire. Where the flanks meet with the head of the fire, are the fire’s shoulders. The shoulders designate where the head can move at any time since winds can vary 10 degrees here and there. A finger is produced during a rapid wind change. Winds can change erratically on hot days, in canyons, or over large fires. When that happens, what usually was the flank, now has become the head of fire. If the wind shifts back and the original head takes off again, the short lived head is now a finger, a small piece of fire jutting out the side of the main burn.
A spot fire is created by embers flying in the air ahead of the head of the main burn. These are very dangerous because they make any direct attack on the head of the fire worthless. Black is everything that has burned. Islands are unburned areas surrounded by black. And finally the green is the unburned area outside the fire. Obviously, the goal is to keep as much green from becoming black.
Geography (terrain) can really affect fire behavior. Fires can travel up chimneys (small drainage off the side of a hill that can look like wrinkles in between hills.) and up the sides of chutes (shallow, rounded canyon typically made by drain water). Gullies are a little bigger then a chimney. These are dangerous places to be. Fires can travel up steep slopes very fast with minimal wind.
Along with geography, the fuel also affects the fire’s behavior. Fuel is whatever the fire consumes that makes it continue to live. Fuel types can be grass, scrub oak, mazanita, forest or timber, rock (doesn’t burn), snags and many other types of vegetation. Fuel characteristics describe the state of the fuels. Are they dry, or are there lots of snags? A canopy is a bunch of leaves on tops of trees that create a roof effect on the forest floor. If a fire burns below, the heat can get trapped inside the canopy and when the fuel reaches a combustible point, the entire canopy can suddenly explode into flames. Dead snags, frost or bug damaged trees are ripe fuels, Live trees usually survive fast moving fires but a number of dead trees and snags around a live tree can slow the fire down and prolong the exposure to the live tree.
If tall trees are close together creating a common canopy, fire can travel through the tops of the trees above ground and never burn the ground. This is VERY dangerous and is called crowning. Firefighters can suddenly be trapped all around by fire if the fire sneaks above them and behind them. This also creates danger of falling burning snags and limbs from above to the ground, which help start the ground fires. With a little wind’s help, this scenario creates a firestorm. Firestorms are a 100-400ft tall walls of flame advancing forward with intensity. The survival rate of living through a firestorm is very low if a firefighter gets caught in one. All life, fuel and structures in the path will be destroyed. Firefighting efforts stop at this point until the firestorm dies down to a manageable level. I’ve survived a firestorm during the Jones Fire in Shasta County, California. While standing in a 5 acre clearing the forest around us exploded in flames as the advancing fire approached and passed over and around us. After it passed, all the engines and fighters hopped back in and started chasing the fire down. What an experience.
The fuel moisture is how much moisture the fuel is retaining. Higher fuel moisture prevents fuel from easily burning. Fuel temperature also affects the fuel’s ability to burn. If the fuel has been sitting out in direct sunlight increases the fuel temperature.
Of course weather is a big player in fire behavior. Wind and air temperature are the two enemies of fire fighting. Wind can spread a fire into an uncontrollable inferno and high temperatures can lower the performance level of a fire fighter, forcing them to work slower, take frequent breaks, and heighten the safety awareness of heat exhaustion etc.
If winds get fast enough a fire can travel fast across all sorts of terrain. Watching clouds and tree tops can help determine what the winds are doing. Having winds stay in one direction at least allows firefighters to focus in one direction, however shifting winds make a fire unpredictable, and impossible to determine where to place resources to fight the fire. The head of the fire can be anywhere at any given time. Probably the worst aspect of wind is the role it plays on firefighting aircraft. Due to ever increasing safety, firefighting aircraft such as air tankers and helicopters can’t fly over a fire with fast winds. Without the brute force of the aerial units, a fire can burn unchecked for a long time until the winds die down. Shifting winds can also cause fire whirls, small tornado vortexes of flames.
As a scanner listener who is in the area, you can observe the smoke column on the fire and determine how the winds are at the incident. Is the smoke column leaning in one direction (surface winds pushing the fire along?) Does the column go up and then get sheared off at the top (typical of a wind current above ground,) or the column going straight up when no wind is on the incident.
Now that you know how a fire works, behaves and causes grief to firefighters, how do the firefighters attack it? There are two methods, a direct attack and an indirect attack. In a direct attack, firefighters are on the fireline putting out active flame, putting water directly on the fire, attacking the head, and in the most danger. An indirect attack occurs when the fire is too dangerous to be close to. This usually happens in large forest fires where the fire travels too fast to keep up on the fireline edge. In this case, firefighters will set up a defense barrier ahead of the advancing fire.
Direct attacks are the philosophy of many fire departments, pounce on the fire with everything they have to keep it small and in control. In a direct attack however, a fire’s actions will determine the response from a firefighter. This forces the firefighter to constantly be alert and ready to change a tactic or ideas. A technique called Mobile Attack (see diagrams) takes 4x4 fire engines off road and putting out fire quickly. The engine pulls off the road and creates an anchor point, usually a spot along the road so the fire can’t go around the fire line. Once an anchor point is established, a fire fighter takes a hose off the front of the engine and walks (or runs) in front of the engine spraying water and creating a wet line along the edge of the fire. The engine follows, driving off road. This attack is usually along the flanks of the fire, approaching the head at the end. The pincer attack is when two engines start a mobile attack on both flanks of the fire. They advance towards the head of the fire, meeting at the head and “pinching” the fire out, like the pincers of an earwig. In a tandem mobile attack, 2 engines start on a mobile attack on the same flank. The lead engine creates the wetline and advances forward. The rear engine follows, putting out any little hot spots missed from the lead but conserving their water. When the lead engine runs out of water, the second engine immediately takes lead and continues the wetline with no break. The lead engine goes back for more water and tries to get back to the second engine before it runs out of water also. There can be 3 or 4 engines in a tandem attack, creating a never-ending source of water for a wetline. After a wetline is laid, a scratchline is created (by quickly scratching away light fuels with hand tools) to keep flames from advancing.
If the terrain is too rough for mobile attack, the engine will stay on the road, and firefighters will grab a hoseline and walk along the fire’s edge, pulling the hose along. When they run out of hose, they clamp it shut at the end, and a second firefighter carrying 100ft of more hose on their backs attaches it to the existing hose. They unclamp, putting water into the extended hose and fight more fire for 100 more feet. This can go on until they run out of hose or lose water pressure. This technique is called a progressive hoselay.
Indirect attacks allow firefighters to stay out of the fire’s danger. They look ahead of the fire’s path and determine where the best location is to take stand against the fire. Here they start bulldozing and hand line cutting (with hand tools) a large swath of dirt across the path of the fire. This technique takes away any fuel for the fire to consume and it dies out. It also allows firefighters to control the fire’s actions, rather then the fire’s actions control the firefighters. Large forest fires are almost always fought indirectly.
Aircraft help control fire from the air. An airtanker or water bomber can unleash fury on a fire. While water bombers directly attack fires, air tankers with retardant drop their load just ahead of the fire’s path to retard or slow the fire’s advance so the ground pounders (firefighters as seen from the air) ahead have more time to build a large fireline. Helicopters are used to drop precise bucket loads of water on hot spots near the edge of a fire to keep it from spreading or spotting over a fire line. When a copter first arrives on scene, it lands and drops off an elite crew of firefighters to help the ground pounders fighting the fire. Helicopters can also drop their bucket and pick up an injured firefighter off the fireline and to help quickly.
When a fire has a fireline all around the fire, and the imminent threat of spread has stopped, the fire is contained. Once all threats of spread beyond the fire line are taken away, the fire is controlled. At this point, mop up occurs. Firefighters go through the entire fire and put out the hot spots, make sure the fire line is intact, and clean up the equipment used. Fire fighters head back to the station, clean off the engines, and get ready for the next fire.