Somewhere in the country, a crew of firefighters will initiate a fast and aggressive interior attack at a residential structure fire only to be engulfed in a rapidly advancing and blinding wall of fire. As a result, the crew will instantly become disoriented and some will not be able to evacuate the structure.
Risk management often used by firefighters during interior structural firefighting operations involves the act of avoiding the anticipated danger within the structure. Another method to manage risk on the fireground consists of using a "risk-benefit analysis." Conversely, a risk-benefit analysis makes the assumption that the risk is known. However, a safety problem identified concerns the fact that in several fatal wind-driven fire cases examined, firefighters either overlooked or were totally unaware of the extreme danger associated with the wind speed and direction in relation to the position of the fire.
The oversight of this key fireground factor during the initial size-up was a contributing factor that ultimately and unfortunately lead to unfavorable outcomes. With appropriate planning, training, and tactical adjustments however, extremely dangerous wind-driven fires can be recognized so that firefighter fatalities may be prevented.
As 12 to 15 mph winds gusted up to 24 mph, pressurized a vented fire on the Charlie side, San Antonio, TX, firefighters were engulfed by a rapidly spreading, wind-driven wall of fire after advancing an 1 3/4-inch handline through the front door at this two-story residence (see Photos 1 through 4.) Although firefighters were temporarily disoriented by the fire, they all made a narrow escape.
Occupants managed to safely exit the structure prior to the firefighter's arrival (see Photo 1.) A 360-degree walk-around revealed fire venting out of the first floor windows on the Charlie side (see Photo 2.) During the incident, fire quickly spread from the first floor on the Charlie side, up to the second floor and into and across the attic space. The wind-driven fire then burned through the roof on the Alpha side of the home (see Photo 3.) A defensive attack was used to safely control this rapidly spreading fire. On the Alpha side, the force of the wind pushed fire through the home and out of the window on the left and the front door located on the right (see Photo 4.) Although the front door served as the firefighter's point of entry, it unfortunately also acted as a dangerous vent point for the wind-driven fire.
The Need To Consider The Wind
According to Dan Madrzykowski of the National Institute of Standards and Technology (NIST), the Fire Fighting Technology Group, FFTG, a branch of NIST, completed a seven-year study on positive pressure ventilation (PPV). As part of the study, the FFTG also conducted eight experiments to examine the impact of wind on fire spread through a multi-room structure involving a high-rise building.
Tests conducted determined that an external wind speed of as low as 10 mph could cause a vented room fire within a structure to quickly spread from an apartment unit to a vent point, represented by a stairwell door. The spreading fire had floor-to-ceiling and wall-to-wall fire involvement with blow torch characteristics.
In addition, temperatures within the flow path of fire measured in excess of 1,112 degrees F. These excessive temperatures were determined to be too high for even fully protected firefighters to survive. One aspect of these findings which should be of special concern to all firefighters is that although these results where determined during simulated high-rise apartment fire conditions, the effects of a 10 mph wind can have similar fire results even in residential structure fires; the types of structure fires firefighters respond to most often.