The meter is designed for general fire danger forecasting purposes and is based on the expected behaviour of fires burning for an extended period in high eucalypt forest carrying a fuel quantity of 12.5 tonnes per hectare and travelling over level to undulating topography. The behaviour of individual fires can be predicted with reasonable accuracy providing the effect of fuel quantity and slope is taken into account. The rate of perimeter spread is generally three times the rate of forward progress but may increase to a factor of four on a large irregular fire.
Fires travel upslope with the prevailing wind faster than on level ground.
Corresponding reductions occur on downslopes. Fires in low quality eucalypt forest tend to spread at faster rates than those shown, due to greater wind movement near the ground. However, the spotting potential is generally lower. The meter can be used to determine broad control burning conditions although a high degree of precision should not be expected. The rate of forward spread refers to a moving flame front which is only affected by relatively short distance spotting.