What are the three primary inputs for wildland fire behavior calculations in S-390?

• A. Fuel, Weather, Topography
• B. Fuel, Wind, Terrain
• C. Fuel, Temperature, Terrain
• D. Fuel, Humidity, Area

Answer: (A)

Wildland fire behavior calculations hinge on three essential inputs: the fuels present, the weather conditions, and the topography of the landscape. The fuel determines how much material is available to burn and how easily it will ignite, dry out, and sustain combustion. Weather provides the driving forces that influence spread and intensity—wind speed and direction, temperature, and humidity all shape drying rates and flame propagation. Topography shapes how a fire preheats fuels and accelerates, with slope, aspect, elevation, and terrain features changing the rate and direction of spread.

This is why the best answer lists Fuel, Weather, and Topography. Wind is part of weather, not a separate input, so singling it out misses the broader weather influence. Temperature alone doesn’t capture the full weather impact, since humidity and other factors also matter. Area isn’t a primary driver of fire behavior, as it reflects scope rather than the mechanisms that govern spread and intensity.