When engines entrap
Over the past few decades, agencies and departments involved in the suppression of wildland fires around the world have grown more and more dependent on the use of engines.
Ranging from the smallest units that hold less than 100 gallons of water to those that carry nearly 1,000 gallons and can apply foam and retardant, engines are the backbone of wildland operations in areas with roads all around the world. The engines transport firefighters and their tools and carry water and hose. With their ability to pump water extended distances via hose lays, engines give wildland firefighters an increased ability to break the fire triangle by cooling the fire and allowing hand crews to complete the job.
The use of engines in suppression activity isn't limited to the United States. Volunteer firefighters in Australia are almost exclusively tanker based, and European countries like Spain, Greece and France depend heavily on engines. As in the United States, the engines used in these countries have grown much more specialized — and expensive — during recent years.
Although engines fill a vital role in fire suppression around the world, they are subject to some unique problems in addition to those faced by “ground pounders.” Probably the most significant of these problems to wildland firefighters is the risk of burnover while operating the engine on the fireground.
Over the past 20 years or so, U.S. firefighters have too often found their lives at risk when they and their engines were burned over by fast-moving fires.
Fire engine entrapments have occurred from California to Idaho to New York, with engines damaged or destroyed and firefighters burned or killed. Several of the burnover instances have been well documented for training purposes, including the 1990 Wenatchee Heights burnover in Washington; the July 1995 Point Fire outside of Boise, Idaho; and the October 1996 Calabasas Fire burnovers during a Santa Ana wind event in Los Angeles County.
Of course, U.S. firefighters aren't alone in becoming trapped with their engines. Bruce Paix, a volunteer captain with South Australia's Country Fire Service near Adelaide, has documented most of the tanker burnovers that have occurred in Australia since 1980.
Paix details nearly 20 separate burnover events, including the seven that occurred during the horrific Ash Wednesday Fires that plagued Australia on Feb. 16, 1983. On that day, eight tankers in Victoria and South Australia were trapped by fast-moving bush fires, and 14 firefighters died.
In December 1998, another major loss of life occurred in Victoria when five volunteer firefighters on a Country Fire Authority engine died during a brief flare-up in the Linton Fire. Just a few feet away, five firefighters in another engine were spared when their protective spray system had enough reserve water to protect them.
Other significant firefighter fatalities involving engines have occurred in Spain and Greece in the late 1990s, reinforcing the international scope of the problem.
The nature of the engine/tanker burnovers and the resulting injuries or deaths of the firefighters are nearly identical around the world. In short, firefighters are trapped by fast-moving fires, and they must decide to remain with their engines or attempt an escape.
Some of those who choose to stay with the engines must later abandon them when the windows crack and blow out from the intense heat. High levels of radiant heat also can cause the cab's interior components to smolder and give off gases. These factors, combined with heavy smoke, can cause firefighters to abandon the apparatus and risk exposure to high levels of radiant and convective heat.
In late 1995, an investigation report was issued for the Point Fire fatalities. Two volunteer firefighters from the Kuna (Idaho) Fire Department had died when their engine stalled out and was burned over on a Bureau of Land Management fire outside of Boise. Neither of the two firefighters had wildland protective clothing or fire shelters, and they remained in their engine's cab.
The report asked that the U.S. Forest Service's Missoula Technology and Development Center study the survivability of engines and fire shelters under identical conditions, so that fire agencies could train their firefighters in the appropriate response when trapped in an engine burnover situation. MTDC personnel obtained old and surplus engines from the Florida Division of Forestry, Los Angeles County Fire Department and Montana's Department of Natural Resources and Conservation. Burnover tests were conducted in 1996 under field conditions that compared conditions inside both engine cabs and fire shelters.
The MTDC studies showed that the engine cab could be a survivable environment during short duration, low- to moderate-intensity fires, but that the cabs were subject to filling with smoke and the plastic and vinyl interior components would release gases. Of course, external components such as tires, mud flaps and other accessories would catch fire. The unstated conclusion of the study: You may survive in an engine cab, but your chances are greatly improved in a fire shelter.
The technical report on the study and an accompanying video are available from the Technology and Development Center in Missoula, Mont. The extensive photo and video documentation since have been used for training purposes.
Over the past 25 years, recurring burnovers around the world have resulted in an ongoing effort on numerous fronts to improve the safety of firefighters in engines and tankers. Because the problem is common to so many regions, an improvement developed in one area may have a direct and immediate application half a world away.
For example, while most of the Australian bushfire organizations don't use fire shelters, they have been strong proponents of keeping a heavy wool blanket in their tanker cabs for each firefighter aboard. Although the wool has no reflective capability, it does reduce the amount of radiant heat that can reach the entrapped firefighters.
There were problems, however. The bulk of the wool blanket doesn't fit well in tankers that are already crowded with other essential fire equipment, so systems were designed that fasten the blankets to the interior roof of the tanker's cab. Even so, there are questions concerning the ability of firefighters in the cab to quickly deploy the blankets, which measure 2 meters by 1.8 meters.
In both Spain and Australia, tanker spray protection systems are widely used and accepted as an integral part of a firefighter's safety system. The mechanics of engineering such a system, as well as ensuring that it will have an adequate volume of water when needed, is a constant challenge for fire managers and equipment developers alike.
The system developed by Spain's Andalusia Fire Service uses a deluge system configured around the engine to adhere closely to the engine's outer shell. It has been successfully used on numerous occasions in southern Spain, where the Mediterranean fuels are very similar to those found in Southern California. In Australia, many of the states have adopted a spray nozzle system that's mounted to provide a heavy mist above the tanker, creating a survivable zone for firefighters both in the cab and in the rear-facing “crew haven” area behind the cab.
A constant challenge to fire safety personnel, managers and engineers is developing a system that forces firefighters to retain the critical volume of water needed to protect their engine, and ultimately themselves. Crew members shouldn't, under any circumstances, be able to use water intended for tanker protection on regular fire operations.
That tenet was emphasized following the December 1998 Linton Fire fatalities in Victoria. Those deaths became even more tragic when it was discovered that one of the engines driving along the primitive trail had used all of its water for firefighting before going back to refill. As a result, all five firefighters aboard perished when the fire overtook them. Another engine had kept a reserve of water in its tank for protection and escaped unscathed.
In conjunction with the New South Wales Rural Fire Service in Sydney and Commonwealth Science and Industry Research Organization, the Australasian Fire Authorities Council is conducting studies to quantify not only the amount of radiant heat flux that a vehicle can withstand, but also how much water volume is needed in the reserve tank to lower the levels of heat reaching the interior in a set amount of exposure time.
To do that, the researchers are developing a full-sized radiant heat test chamber where engines can be exposed to carefully measured and fully repeatable conditions. The chamber will allow for the analysis of heat effects on engine components and design, as well as on protection devices such as spray systems.
Because the market for engines and tankers is relatively small in countries like Australia and Spain, departments are often forced to accept a standard, off-the-shelf truck model offered for the general commercial market. These vehicles can pose a serious challenge to those trying to enhance firefighter survivability in an engine's cab area.
Sometimes the only option is to alter these stock trucks. With data from the MTDC study showing the off-gassing from components in the interior of the engine's cab, it became apparent that materials such as dashboard liners and sound-deadening materials in the doors could pose serious risks to firefighter health and safety. Paix has been working to remove those components from South Australia's County Fire Service engines, and replacing the door panels with a non-combustible material that can absorb the exterior radiant heat without off-gassing or catching fire. These tankers are leading the way Down Under with a relatively simple fix to a widespread problem affecting firefighter safety.
Off-the-shelf models can pose other harder-to-solve problems. For example, these trucks are often designed with large window areas, including in-door panels and front windshields that extend nearly to the ground. While these features enhance driver visibility and safety in the commercial arena, they may endanger firefighters in an entrapment or burnover situation as glass transfers much of the radiant heat it receives, in this case into the cab.
An American company, Storm King Mountain Technologies, is working with fire agencies in both the United States and Australia to develop window fire curtains and fire shelter panels for the exterior crew compartments. These window curtains and shelter panels will greatly reduce the level of radiant heat that reaches the interior of the engine cab, especially if the windows fail under moderate to extreme heat conditions.
Another American company, KME, is producing customized fire engines designed with the protection of the firefighter in mind. The manufacturer's urban-interface FlameShield engine incorporates double-pane thermal windshield glass and high temperature — tempered side windows with a track-mounted window protection screen system. The vehicles also have high-temperature door gasket materials and insulated cab interiors.
The introduction of motorized firefighting equipment has made firefighters' lives considerably easier over the past 50 years. The tankers and engines we use today are generally reliable, well designed and expensive to replace — but they can be replaced if necessary. Individual firefighters are the only piece of the wildfire equation that is irreplaceable. No matter how much they care about their engine or its monetary value, it's not worth dying over.
For wildland firefighters to reduce the risk of being involved in a burnover, they need to recognize those situations that have historically led to engine burnovers:
- Poor communications with those who have a good view of the fire,
- Protecting indefensible structures,
- Using roads that deadend or don't have adequate turn-around space, and
- Taking the engine onto the fireground with out a good anchor point to protect your flank.
Although there are plenty of rules, policies and guidelines to help keep a fire crew and its engine out of these situations, events sometimes degenerate to a point where entrapment or burnover become inevitable. What then?
The first step is to analyze the surrounding terrain and fuel conditions to position the engine where it will receive minimal radiant heat load. Next, look at the engine: Does it have a standard interior, with lots of plastics and poly-vinyls that can off-gas and smoke up the interior? Is it equipped with any special protection features? Will it be a survivable environment for the next 15 to 30 minutes based on fire behavior?
If the engine isn't viable, do all crew members have fire shelters? Is there a good deployment site with either very sparse fuels or “good black”? Is there a nearby structure that can offer protection when the flame front passes?
Consider all these factors, and then make a decision. Once you decide to ride out a burnover in an engine, you're committed. Knowing the risks will help ensure its the best choice in a deadly situation.
Dick Mangan has been the fire and aviation program leader at the Missoula Technology and Development Center since 1989. His major responsibilities include developing equipment for wildland firefighters, primarily personal protective equipment and equipment for smokejumpers. He serves on the National Wildfire Coordinating Group's fire equipment and safety and health working teams, and is chair of the National Fire Protection Association's technical committee for wildland fire personal protective equipment. Mangan has a bachelor's degree in forestry and more than 20 years of experience at ranger districts and national forests in Oregon and Washington.
The KME Flameshield Interface pumper provides crew safety in a custom apparatus. Built on the Renegade Square MFD chassis, the unit features a burnover protection system that allows a fully geared crew to survive a burnover of up to 2,000°F for five minutes.
Flameshield is a thermally insulated, track-mounted window protection system that includes double-panel thermal windshield glass and high temperature — tempered side windows. The track system is set for rapid deployment to minimize setup time during emergencies. There are also high-temperature door gasket materials, a fully insulated cab interior and an all-aluminum cab for maximum heat dissipation.
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