National Wildfire Coordinating Group

Wildland Urban Interface Watch Outs


The primary consideration in wildland urban interface (WUI) is to assure firefighter and public safety. It is essential to assess potential fire behavior, ingress/egress routes, nature of the threat, hazardous materials, and available water supplies before engaging in the protection of any structures. The first step is to assess whether firefighting operations can be conducted safely.

Consider the Wildland Urban Interface Watch Outs in completing a risk analysis for the urban interface area to be protected. Remember there are three categories of structures:

  • Those that are not threatened.
  • Those that are threatened.
  • Those that have already been lost or are too dangerous to protect.

Wildland Urban Interface Watch Outs:

  • Poor access and narrow, one-way roads. A rapidly spreading fire could trap apparatus and personnel before they can turn around or move away from the flames and smoke.
  • Observe bridge limits. Exceeding bridge limits could lead to bridge failure with a resultant blocking of ingress/egress routes that could result in the loss of an escape route or loss of equipment.
  • Inadequate water supply. Without a reserve supply of water, the fire can overtake an area before the fuels can be cleared away.
  • Natural fuels are located 30 feet or closer to structures on level ground. Remember structures on slopes require greater clearance.
  • Structures are located on canyon slopes or in chimneys on slopes of 30% or more with continuous, flashy fuels. The resulting rate of spread of any fire in this terrain can quickly extend beyond control.
  • Extreme fire behavior:
    • Situations involving crowning, large flame heights, and erratic fire behavior can extend in an unpredictable manner beyond the control of any number of personnel.
    • Strong winds of 25+ miles per hour: Winds increase the chance of spotting over the heads of firefighters and trapping them between both fire areas. Winds also cause greater preheating of fuels in the path of a fire front.
  • The need to evacuate the public, livestock, pets, and/or animals. This critical activity can pull personnel from the firefighting activity and can distract attention from fire behavior at a time when the greatest alertness is needed.
  • Propane and above ground fuel tanks that are next to wooden structures or close to vegetation.
  • Power lines and poles:
    • What is their location in relation to the structures that are being protected? Watch for both overhead and downed power lines.
  • Local citizens are attempting suppression activities. Lack of knowledge in fire suppression may lead to unsafe tactics.
  • Airtanker retardant drops and helicopter bucket operations:
    • Establish communications and keep fire personnel out of the drop zone.


Operational Engagement
Page Last Modified / Reviewed: 
Mar 2022

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