Building a Fire Organization 



489 



reach the fire, hit it hard, and bring it 

 under control quickly. 



An area that has a large number of 

 fires each year may require small sup- 

 pression crews strategically located and 

 in sufficient strength to assure rapid 

 control under normal conditions. The 

 location and strength of initial-attack 

 forces must be determined and ar- 

 ranged for in advance. 



Weather, fuels, and the efficiency of 

 personnel and equipment determine 

 the speed and strength of initial attack 

 needed for any fire. Planning the ini- 

 tial attack is primarily concerned with 

 the manpower and equipment that 

 should be readily available under dif- 

 ferent degrees of fire peril. 



Climatic conditions, especially rela- 

 tive humidity and wind velocity, 

 greatly affect fire behavior. Atmos- 

 pheric measurements and forecasts and 

 various devices for measuring dryness 

 of fuels are therefore valuable tools in 

 forest-fire control. However, weather 

 factors are too variable to be given 

 much consideration in planning an 

 organization for initial attack. Rather, 

 they are used to alert the entire or- 

 ganization and often influence the 

 temporary strength and placement of 

 initial-attack forces. 



Under a given set of weather condi- 

 tions, fire travels much faster in some 

 forest fuels than in others. The speed 

 with which a fire burns in a specified 

 type of fuel under normal circum- 

 stances is called the "rate of spread." 

 Also, different fuels may vary widely in 

 the relative ease or difficulty of con- 

 structing fire lines or otherwise fighting 

 a fire. "Resistance to control" is the 

 term applied to it. Forest fuels are, 

 therefore, rated according to those two 

 basic factors. 



Different methods can be used for 

 classifying major fuel types on the basis 

 of the two factors. 



One is to determine and assign a 

 composite rating for each important 

 type of fuel. For example, dead grass 

 would be designated "LE" indicating 

 "low" resistance to control and "ex- 

 treme" rate of spread. 



Another method designates the ma- 

 jor fuel types as I, II, III, and IV, 

 which represent in relative order the 

 greatest spread plus highest resistance 

 to control. 



Regardless of the system used, the 

 first step in the development of the 

 initial-attack plan is the mapping of 

 the major fuels and the rating of com- 

 bined effects of their respective resist- 

 ance to control and rate of spread. 



The second step is to set up stand- 

 ards for the time allowed the nearest 

 suppression force to reach a fire in 

 each major fuel-type zone. This is 

 called "travel" time. It must be fast 

 enough to permit effective attack on 

 the front of the fire before it becomes 

 too difficult to handle. 



Increasing the strength of the ini- 

 tial force by adding more men or mo- 

 bile equipment, such as tank trucks, 

 will provide more time to reach the 

 fire. In other words, the greater the 

 strength of initial attack, the slower 

 the travel time might be. 



The third step is to determine the 

 needed strength of the initial-attack 

 forces. The guide here is the antici- 

 pated size or perimeter of the fire in 

 the particular zone at the time the fire 

 is reached. That is determined by mul- 

 tiplying the rate of the spread by the 

 travel-time standard, both of which 

 have already been established. Even on 

 active, small fires not more than half 

 of the calculated perimeter requires 

 immediate action, because if the front 

 of the fire is controlled the less active 

 parts can be handled later. The forces 

 required to construct and hold a fire 

 line along the critical perimeter can 

 be determined from a study of initial- 

 control measures on previous fires in 

 the zone. For small fires in certain 

 areas, this theoretical calculation of 

 the number of men needed will prob- 

 ably be larger than can be economi- 

 cally justified. Other means should be 

 explored in such cases to reduce the 

 size of the crews. The solution may be 

 tank trucks, small tractor-drawn plows, 

 or other machines that will reduce the 

 needed manpower. 



