Wildfire Knowledge Graph · Fire Behaviour
A side portion of a wildfire located between the faster-moving head and the slower rear.
In plain language
Flanks often spread across the dominant direction of travel and can become new heads when wind or terrain changes.
Why it matters
Evacuation and response analysis must account for changing fire orientation rather than treating the perimeter as static.
What does flank fire mean in wildland fire?
Flank fire is a firing technique, not the name for the side of a wildfire. NWCG defines it as lines of fire set into the wind that burn outward roughly at right angles to the wind.
The flanks of a fire are a different concept: they are the portions of the wildfire perimeter roughly parallel to the main direction of spread. Confusing the two terms can make incident reports harder to interpret.
NWCG — flank fire · NWCG — flanks of a fire
See Parts of a Wildfire: head, flanks and rear for the perimeter terminology.