Common Denominators Of Fire Behavior On Tragedy Fires

Weather - Fire Behavior
Page Last Modified / Reviewed: 
May 2020


Five common denominators that contribute to accidents/incidents have been identified through studies of tragedy fires. It is important for firefighters to readily recognize the following common denominators so that future tragedies can be prevented:

  • Most incidents happen on smaller fires or on isolated portions of larger fires.
  • Most fires are innocent in appearance before unexpected shifts in wind direction and/or speed result in flare-ups or extreme fire behavior. In some cases, tragedies occur in the mop-up stage.
  • Flare-ups generally occur in deceptively light fuels, such as grass and light brush.
  • Fires run uphill surprisingly fast in chimneys, saddles, gullies, and on steep slopes.
  • Some suppression tools, such as helicopters or airtankers, can adversely affect fire behavior. The blasts of air from low-flying helicopters and airtankers have been known to cause flare-ups.

Discussion Points:

  • Talk about some instances in which you have been in any of the above situations or experienced any of the overly common denominators.
  • Discuss the frequency of the above situations on a fire, speak about complacency towards the end of a shift/fire season. Come up with examples of ways to combat and/or deal with situations in which you are involved in a common denominator situation.


Additional Resources

Incident Management Situation Report (IMSR)
Incident Response Pocket Guide (IRPG), PMS 461
NWCG Standards for Helicopter Operations, PMS 510
RT-130, Wildland Fire Safety Training Annual Refresher (WFSTAR)
Interagency Standards for Fire and Fire Aviation Operations (Red Book)
Wildland Fire Lessons Learned Center

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