Wildland Fire Suppression Flashcards

The fire behaviour triangle consists of fuel, weather, and:

Answer: Topography

Wildland fire behaviour is governed by the triangle of fuel (type, arrangement, moisture), weather (temperature, relative humidity, wind), and topography (slope, aspect, terrain features). Ignition source starts the fire but does not drive its ongoing behaviour.

In wildland fire suppression, a 'crowning' fire is MOST dangerous because:

Answer: It spreads through the tree canopy and can move faster than firefighters can escape

Crown fires travel through the upper canopy at speeds that can far exceed ground fire rates—sometimes outpacing even vehicles on roads. They dramatically reduce firefighter safety margins and are a primary reason for emergency escape route and safety zone planning.

When constructing a hand guard line around a wildland fire, the correct technique is to:

Answer: Scrape all vegetation and duff down to bare mineral soil along the line

An effective guard line removes all combustible material—vegetation, duff, leaf litter—down to bare mineral soil, eliminating the fuel pathway. Building inside the flame front is unsafe; applying water without a mineral soil line is inadequate for a lasting fuel break.

A wildland firefighter observes that the wind has shifted and the fire is now burning toward their position. The FIRST action they should take is:

Answer: Move to a pre-identified safety zone via the designated escape route immediately

The 10 Standard Firefighting Orders and LCES (Lookouts, Communications, Escape Routes, Safety Zones) framework require immediate retreat to a safety zone when the fire situation changes and positions become unsafe. Suppression, air support requests, and shelter deployment are secondary to immediate escape.

The Canadian Forest Fire Danger Rating System (CFFDRS) Fire Weather Index (FWI) primarily measures:

Answer: The potential intensity and spread rate of a wildland fire based on weather inputs

The FWI system uses temperature, relative humidity, wind speed, and rainfall to produce indices—including spread rate, fuel consumption, and fire intensity—that describe potential fire behaviour under current weather conditions. It does not count active fires or measure specific fuel classes directly.

Aspect (the compass direction a slope faces) affects wildland fire behaviour primarily because:

Answer: South-facing slopes in the northern hemisphere receive more solar radiation, producing drier fuels

In the northern hemisphere, south-facing slopes receive more direct solar radiation throughout the day, which dries fuels and raises temperatures relative to north-facing slopes. This typically produces higher fire danger and faster spread rates on southern exposures.