1.2 Wildfire Entrapment Avoidance – Basic Procedures

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Wildfire Entrapment

BCWS:

Fire entrapment is a life-threatening situation where fireline personnel are threatened by a sudden change in fire conditions and are unable to use escape routes to access safety zones.

CIFFC:

Entrapment occurs when firefighters are in danger of being burned over.

Wildfire Entrapment Avoidance

The use of fire suppression strategies and tactics that take into consideration current and predicted fire behaviour so as to avoid fire entrapment.

Fire entrapment avoidance requires that fireline personnel recognize the fuels, weather and topography that can cause hazardous fire behaviour and make use of lookouts, anchor points, communications, escape routes and safety zones to prevent fire entrapment. 

  • Never fight fire in any situation where safety is compromised.
  • Be situationaly aware at all times.
  • LACES in place at ALL TIMES.

Fire Behaviour Factors

  • Be aware of hazardous fuels.
  • Be aware of hazardous WX.
  • Be aware of hazardous topography.

Same fire, same day, firefighters had to withdraw. What changed?

Factors That Influence Fire Behaviour

FUELS WEATHER TOPOGRAPHY
Moisture Content* Wind* Slope*
Size Precipitation Aspect
Arrangement Relative Humidity Terrain/ Landform
Quantity Temperature Elevation
Continuity
*most influential factor

HAZARDOUS FUELS

  • Fine fuels, (cured grass, cured logging slash)
  • Dead or diseased fuels, (beetle-killed timber)
  • Low fuel moisture conditions, (drought, late summer)
  • Closely-spaced fuels, (coniferous regen)
  • Unburned fuels between personnel and active fire perimeter
  • Numerous deadfall, (impedes movement, increases fuel loading)

Discuss fuel hazards

HAZARDOUS WEATHER

  • Winds increasing or changing direction, erratic, (frontal passage, atmospheric instability, altocumulus lenticularis).
  • High temperature, (convection, instability, FF fatigue).
  • Low humidity, (cross-overs).
  • Periods of drought, (increasing fuel quantities, higher fire intensities).
  • Convective storms, frontal passage, (unpredictable winds, lightning activity, rain/ hail risk, impacts on aircraft ops).

Above: Examples of inversion, crossover, and cloud development.

Above: Examples of different cloud types.

Above: An example of how wind direction/speed can affect a wildfire.

HAZARDOUS TOPOGRAPHY

Steep slopes, (limits firefighter mobility, increased fire spread rates, rolling rocks and debris).

South or southwest aspect, (hotter, drier).

 

Discuss topographical hazards