A number relating to the potential amount of effort needed to contain a single fire in a particular fuel type within a rating area. NFDRS uses a modified version of Bryam's equation for flame length - based on the Spread Component (SC) and the available energy (ERC) - to calcuate flame length from which the Burning Index is computed.
The equation for flame length is listed below:
FL=j[(SC/60)(25(ERC))]0.46where (j) is a scaling factor, (SC) is the spread component, and (ERC) is the energy release component.
Consequently, the equation for the Burning Index is:
BI=j1*FLwhere j1 is the Burning Index scaling factor of (10/ft). Therefore, dividing the Burning Index by 10 produces a reasonable estimate of the flame length at the head of a fire. A unique Burning Index (BI) table is required for each fuel model.