Fire is a natural process that plays an important role in maintaining the health of many forest and grassland ecosystems, but wildland fire can also endanger the homes and lives of people living in or near wildlands. Areas where structures and other human development meet or intermingle with undeveloped wildland are commonly referred to as the wildland-urban interface. Forest Service and university researchers estimate that more than 42 million homes in the lower 48 states are located in such areas, though the risk from wildland fire in these areas varies widely. When wildland fires threaten homes, personnel and equipment from federal, state, local, or tribal firefighting organizations, as well as contractors or the military, may be mobilized for fire suppression. Effective communication among firefighters and other public safety personnel, primarily using handheld portable radios and mobile radios in vehicles, is needed to ensure safe and successful firefighting efforts. Although people choosing to live near wildlands may enjoy many benefits from their location, they also run the risk that their homes may be damaged or destroyed by a wildland fire. Wildland fires have destroyed an average of 850 homes per year since 1984, according to a National Fire Protection Association official. However, losses since 2000 have risen to an average of 1,100 homes annually. These losses occurred in many states throughout the nation, including Arizona, California, Florida, and New Mexico, although California has suffered the highest losses overall. Losing homes to wildland fires has long been a problem. Severe fires across the northern United States in 1910 resulted in the destruction of entire towns and, in California, homes have been destroyed in nearly every decade since 1930. The problem is not limited to the United States; wildland fires have damaged or destroyed homes in other countries as well, including Australia, Canada, and France. Most remote wildland fires are ignited by lightning; and humans, intentionally or unintentionally, start the rest. Fire requires three elements—oxygen, heat, and fuel—to ignite and continue burning. Once a fire has begun, a number of factors—such as terrain, weather, and the type of nearby vegetation or other fuels, including structures—influence how fast and how intensely the fire spreads. For example, fire can burn very rapidly up a steep slope. Adverse weather conditions—especially hot, dry weather with high winds—together with adequate fuels can turn a low-intensity fire into a high-intensity fire that firefighters may be unable to control until the weather changes. Any combustible object in a fire’s path, including homes and other structures, can fuel a wildland fire and sustain it. If any one of these three elements is removed, however—such as when firefighters remove vegetation or other fuels from a strip of land near a wildland fire, called a fire break—a fire will normally become less intense and eventually die out. Wildland fires can threaten homes or other structures in several ways: Surface fires burn vegetation or other fuels near the surface of the ground, such as shrubs, fallen leaves, small branches, and roots (see fig. 3). These fires can ignite a home by burning nearby vegetation and eventually igniting flammable portions of it, including exterior walls or siding; attached structures, such as a fence or deck; or other flammable materials, such as firewood or patio furniture. (In the electronic version of this report, a video clip illustrating surface fire is available at http://www.gao.gov/media/video/d05380v1.mpg.) Crown fires burn the tops, or crowns, of trees. Crown fires normally begin as surface fires and move up the trees by burning “ladder fuel,” such as nearby shrubs or low tree branches. Crown fires place homes at risk because they create intense heat, which can ignite portions of structures, if flames are within approximately 100 feet of the structure, even without direct contact. Figure 4 shows a crown fire burning in trees. (In the electronic version of this report, a video clip illustrating crown fire created in an experiment in the Northwest Territories of Canada is available at http://www.gao.gov/media/video/d05380v2.mpg.) Spot fires are started by embers, or firebrands, that can be carried a mile or more away from the main fire, depending on wind conditions. Firebrands can ignite a structure by landing on the roof or by entering a vent or other opening. Firebrands can ignite many homes and surrounding vegetation simultaneously, increasing the complexity of firefighting efforts. (In the electronic version of this report, a video clip illustrating a cloud of firebrands is available at http://www.gao.gov/media/video/d05380v3.mpg.) Homes can be more flammable than the trees, shrubs, or other vegetation surrounding them (see fig. 5). Wildland fires can cause extensive and costly damage, but when compared with losses from other natural disasters or even other residential fires, losses from wildland fires are relatively low. From 1983 through 2002, costs and damage from wildland fires in the United States exceeded $1 billion in 2 years and $2 billion in 3 years. During this same 20-year period, however, wildland fires accounted for only about 2 percent of total insured losses from all natural disasters. In contrast, tornadoes accounted for 32 percent of total insured losses and hurricanes for 28 percent. In 2003, severe fires in Southern California destroyed more than 3,600 homes, with total damages estimated at more than $2 billion but, in comparison, hurricanes in the Southeast in 2004 damaged an estimated one in five homes in Florida, with estimated total damages of $42 billion. Further, houses damaged or destroyed by wildland fires accounted for less than 1 percent of the estimated 400,000 residential fires that occurred annually from 1994 through 1998. Losses from wildland fire could increase in the future, as more people move to wildland-urban interface areas. Census Bureau data for 2000 through 2004 indicate that those states with the largest percentage increases in population growth are in the West and South, including Arizona, California, and Florida, where many wildland fires occur. Officials from California, Florida, and New Mexico told us that the wildland-urban interface areas in their states have grown significantly in recent years, and the growth is expected to continue. In California, an estimated 4.9 million of the state’s 12 million housing units are located in this area, and 3.2 million of these are at significant risk from wildland fire. Addressing threats from wildland fires is a shared responsibility. However, homeowners and state and local governments have the primary responsibility for ensuring that preventive steps are taken to help protect homes from wildland fires. While the federal government does not have a primary responsibility, it has played a role through its efforts to educate and assist communities in taking preventive steps. Because the vast majority of structures damaged or destroyed by wildland fires are located on private property, much of the responsibility for taking adequate steps to minimize or prevent damage from wildland fire rests with property owners. State and local governments, as well as the federal government and nongovernmental groups, help to educate homeowners and others about wildland fire and ways to minimize or prevent property damage. State and local officials also can establish and enforce land-use restrictions and laws that require defensible space and fire-resistant building materials. Finally, homebuilders choose the building materials and construction methods used, in accordance with local building codes, when building a home, and insurance companies reimburse their clients for losses, including those from wildland fires. Once a wildland fire starts, many different agencies assist in the efforts to manage or suppress it. To fight fires, the United States uses an interagency system whereby needed personnel, equipment, aircraft, and supplies are ordered through a three-tiered—local, regional, and national—dispatching system. Federal, state, local, and tribal government agencies; private contractors; and, in some cases, the military, supply firefighting personnel and equipment, which is coordinated through various dispatch centers. The National Interagency Coordination Center (NICC) in Boise, Idaho, is the primary center for coordinating and mobilizing wildland firefighting resources nationwide. NICC is also responsible for coordinating with the Department of Defense (DOD) if military assets are needed. When requests exceed available resources, fires are prioritized, with those threatening lives and property receiving higher priority for resources. Although this interagency response system is an effective way to leverage limited firefighting resources, communications challenges may arise because the various agencies responding to a fire may communicate over different radio frequency bands or with incompatible communications equipment. Problems with communications interoperability occur primarily during the early efforts to suppress the fire, called the initial and extended attack phases, before national and state caches of interoperable radios can be deployed to the incident. Land mobile radio systems are the primary means of communication among public safety personnel operating in a single area. These systems consist of a regularly interacting set of components including a base station, which controls the transmission and reception of audio signals among radios; mobile radios in vehicles and handheld portable radios carried by emergency personnel; and stations, known as repeaters, which relay radio signals (see fig. 6). Radio signals travel through space in the form of waves. These waves vary in length, and each wavelength is associated with a particular radio frequency. Radio frequencies are grouped into bands. Of the more than 450 frequency bands in the radio spectrum, 10, scattered across the spectrum, are allocated to public safety agencies (see fig. 7). The radio spectrum is finite, however, and additional frequencies cannot be added or created.