Fire Captain Practice Test

Slope determines how quickly a fire front moves upslope because heat radiates and convection preheats fuels ahead of the flames more effectively on inclined terrain. As the slope increases, the flame tilts toward fuels upslope and radiant heat reaches them sooner, creating a feedback that speeds ignition and front advancement. In many fire-training contexts, this relationship is summarized by the rule of thumb that the rate of spread doubles for roughly a 20 percent increase in slope. That geometric and heat-transfer effect is why slope is the best answer here—the others influence spread but don’t produce that consistent doubling pattern with slope increments.