NFPA Journal®, March/April 2008
The choice to attack a fire offensively or defensively is critically important, as civilian and firefighter lives will often hang in the balance. When a chief officer arrives on the fire scene, an in-depth, real-time evaluation may require a change in strategy. However, the first-arriving company officer must make the initial offensive-defensive decision.
The burden of making this decision can be heavy, as it may mean sacrificing property and abandoning attempts to rescue trapped occupants. This decision, known as the "burden of command," is most difficult when people are suspected or known to be in the building.
Firefighters are expected to accept significant risk to save a life, but they are not expected to sacrifice their lives when there is no reasonable hope of saving trapped occupants. Nor should they be placed in imminent peril to save property.
Section 8.3.2 of the 2007 edition of NFPA 1500, Fire Department Occupational Safety and Health Program, states that the concept of risk management at an emergency scene shall be used on the basis of four principles:
"(1) Activities that present a significant risk to the safety of firefighters shall be limited to situations where there is a potential to save endangered lives.
(2) Activities that are routinely employed to protect property shall be recognized as inherent risks to the safety of firefighters, and actions shall be taken to reduce or avoid these risks.
(3) No risk to the safety of firefighters shall be acceptable when there is no possibility to save lives or property.
(4) In situations where the risk to fire department members is excessive, activities shall be limited to defensive operations."
To drive home these points, Louisville, Kentucky, firefighters were required to carry a "mission" card that read: As a Louisville Fire Fighter I am willing to accept considerable risk to save another person’s life; I am willing to accept reasonable risk to save another person’s property; I am willing to accept no risk to save what is already lost.
Offensive attacks are usually considered more hazardous than defensive attacks, but defensive attacks are not without risk. When the incident commander (IC) decides a defensive attack is necessary due to structural conditions, building collapse is often a major consideration.
When a fire seriously threatens the structural integrity of a building, firefighters should be moved outside the collapse zone. Any collapse zone that is closer than the building’s height plus an allowance for debris scatter — usually one and a half times the building’s height — is a calculated risk, and the IC must ask whether the expected benefit is worth the increased risk. If the IC decides to conduct operations in the collapse zone, the building’s corners are usually safer than the sides.
If the collapse zone is wider than the effective reach of master streams, defensive attack options are further limited, and a non-attack strategy may be the only safe choice. If it is safe to place apparatus or personnel within the range of available master stream appliances, the IC can either operate fire streams directly into the burning building or use them to cover nearby exposures.
If the main body of fire can be "darkened down" with master streams, directing them into the building is generally the best option, as it reduces the threat to exposures and may reduce damage to the building of origin. However, determining the effectiveness of a direct attack on the building of origin is often impossible. When this is the case, the best fire stream position allows either a direct attack or exposure protection without moving the apparatus or master stream. If available fire streams cannot make a substantial impact on the fire, placing them directly onto nearby buildings is a better option.
Unlike the offensive attack where several firefighters are needed to advance a handheld line, the master stream-oriented defensive attack typically requires one firefi ghter to direct the stream and another to operate the pump. The officer should stand to the side of the master stream to direct it and supervise the operation.
In many cases, two fire companies are assigned to a single master stream, one to supply water and the other to supply the master stream appliance. This results in unassigned personnel at the scene. Unassigned firefighters can relieve firefighters so they can rotate through rehabilitation or be assigned to staging, making companies available for other responses or to augment the attack. Unassigned personnel must be managed to avoid freelancing.
Providing water at large defensive operations may prove more challenging than at most offensive attacks. Many master stream appliances can consume the total pumping capacity of an apparatus. Several operating appliances can exhaust the water system even in areas with reliable, adequate water supplies. To meet demands, supply lines should use large-diameter hose, and water may have to be relayed from more remote sources.
If the building does not collapse during the defensive attack, interior overhaul may be needed. Postdefensive interior overhaul can be extremely hazardous. The building may be structurally unsound, and the weight of water remaining in it could precipitate collapse. Consider positioning master stream appliances around the building for use if needed and establishing a fire watch while the building drains and a structural analysis is conducted. If the fire occurs at night, delaying overhaul until daylight will improve safety conditions. If the building suffers serious structural damage, firefighters must stay out of it, and it must be razed.
Although defensive attacks generally require more water and apparatus than offensive attacks, they require fewer personnel and reduce firefighters’ risks. Defensive fires tend to be more spectacular, but they are easier to handle if the proper precautions are taken.
The IC must always be cognizant of the many factors that lead to a defensive decision. When a fire is so large that the building’s structural support is threatened, a collapse zone should immediately be established. Firefighters should never be needlessly placed at risk.
This column is adapted from the authors’ book Stuctural Fire Fighting, available at www.nfpa.org or (800) 344-3555.