Differentiate between a backing fire and a heading fire.

• A. A backing fire moves with the wind and spreads rapidly; a heading fire moves against the wind and spreads slowly
• B. A backing fire moves against the wind and spreads slowly; a heading fire moves with the wind and spreads rapidly
• C. Both types move with the wind but differ in flame color
• D. A backing fire is always hotter than a heading fire

Answer: (B)

The key idea is how wind direction relative to the fire front affects spread and intensity. A heading fire is the front that moves with the wind, so the flames and heat are pushed into unburned fuel ahead of it. That preheats and ignites fuel quickly, making the fire spread rapidly and with higher intensity.

A backing fire travels into the wind, against the direction the fire is moving. The wind Opposes the flame front, so heat transfer to fresh fuel is slower, flames stay closer to the burned area, and the fire progresses much more slowly and with lower intensity.

This difference is why backing fires are used to establish control lines or burn out areas methodically, while heading fires advance quickly and can be more dangerous to firefighters and resources. The idea that both move with the wind or that flame color dictates spread isn’t the reliable way to predict behavior, and backing being hotter isn’t correct—the opposite is usually true.