9

Defensive

Operations

9

Learning Objectives (1 of 9)

• Compare and contrast a defensive

versus offensive fire attack, explaining

the key differences.

• Explain why an offensive attack is

preferred over a defensive attack.

• Enumerate conditions that would lead to

a defensive attack.

9

Learning Objectives (2 of 9)

• Describe how collapse zone dimensions are

determined.

• Evaluate the effectiveness of master streams

operated from distances required to maintain

a safe collapse zone.

• Discuss the positive and negative effects of

operating a hose stream into a window or roof

opening.

9

Learning Objectives (3 of 9)

• Describe conditions when a direct

defensive attack is preferred as

compared to an indirect defensive

attack (i.e., covering exposures).

• Describe how water should be applied

when protecting an exposure from

radiant heat.

9

Learning Objectives (4 of 9)

• Compare and contrast the use of

handheld hose streams versus master

stream appliances during defensive

operations.

• List two ways the water utility may be

able to increase the total water supply

at the incident scene.

9

Learning Objectives (5 of 9)

• Compare and contrast the use of fog

versus solid streams during a defensive

attack.

• Estimate staffing and apparatus needs

when operating master streams.

• Define conflagrations and group fires.

9

Learning Objectives (6 of 9)

• List common problems leading to

conflagrations.

• Explain tactics used to control a

conflagration.

• Discuss why conflagrations are likely to

occur immediately after a natural

disaster.

9

Learning Objectives (7 of 9)

• List reasons for a non-attack strategy.

• Given a scenario, calculate the

dimensions of the collapse zone.

• Prioritize exposures based on fire

conditions, occupancy, and weather

factors.

9

Learning Objectives (8 of 9)

• Develop an incident action plan for a

defensive fire.

• Develop an incident action plan for a

conflagration.

• Apply defensive tactics to a defensive

fire attack.

9

Learning Objectives (9 of 9)

• Apply defensive tactics to a conflagration.

• Evaluate staffing, water supply, and

apparatus needs for a large-scale defensive

fire.

• Apply NIMS to a defensive fire scenario.

• Determine the probability of a conflagration

for a specified response area.

9

Overview (1 of 2)

• Offensive fire attack

– Preferred strategy

• Defensive fire attack

– Limits operations to the exterior

– Results in larger property loss

– Limits rescue options

9

Overview (2 of 2)

• Offensive/defensive decision based on:

– Risk-versus-benefit analysis

• Solid fire-ground information

• Training and experience

• Staffing available to accomplish interior

attack, water supply, ventilation

9

Defensive Attack (1 of 2)

• Objective: save property and/or protect

the environment

• Easier to handle

• Pose fewer risks if the proper

precautions are taken

9

Defensive Attack (2 of 2)

• Situations:

– Structural integrity concerns, fire

conditions, or other hazards prohibit entry

– Resource needs outweigh resource

capabilities.

– Risk-versus-benefit analysis indicates that

the risk is too great.

9

Collapse Zone (1 of 2)

• Equal to the height of the building plus

an allowance for debris to scatter

– Anything less = calculated risk

• Distance equal to 1½ times the height of

the building

• Can be pre-planned

– Estimated floor height = 12′ per floor

9

Collapse Zone (2 of 2)

• Non-attack strategy: tall buildings

– Water application distance for master streams

• Width of street = limiting factor

– Building evaluated to determine safest position

• IC must consider expected benefits.

– Risk-versus-benefit analysis

9

Evaluating Exposures

• Two types: internal and external

• Internal

– Fire extends from one area to another

within a structure.

• External

– Surrounding buildings/property

9

Defensive Streams

• May spread the fire inside the building

• Fog streams may push fire.

– May also fill an area with steam, helping the suppression effort

• Exterior streams may push fire into concealed spaces.

• Elevated streams may push vented fires back into the building.

9

External Exposures

• Protecting external exposures is critical.

• Should be evaluated in terms of:

– Life safety

– Extinguishment

– Property conservation

9

Prioritizing Exposures

• Based on:

– Distance between exposed structures

– Volume and location of fire

• Radiant heat increases as flame front

increases.

– Extinguish main volume of fire

9

Radiant Heat

• Inversely proportional to the square of

the distance between the heat source

and the exposure

– Closer the buildings = greater radiant heat

– Exposures higher than the fire are also at

greater risk.

9

Protecting Exposures

• Options depend on:

– Available staffing

– Apparatus resources

• Wetting the exposure is most effective way.

• Directing a stream between buildings is less

effective.

– Radiant heat travels through transparent materials

such as water.

9

Master Streams (1 of 2)

• Defensive operations

– Can apply more water from a greater

distance with fewer personnel

9

Master Streams (2 of 2)

9

Elevated Master Streams

• May hinder upward and outward

movement of heat and smoke

– Usually detrimental to the operation

• May push fire back into the building

– Spreads fire into uninvolved areas.

– Reverses positive effects of ventilation

9

Water Supply Needs

• Defensive operations may be more

challenging than offensive attacks.

• Master streams can require total pump

capacity of apparatus.

– Even reliable water systems can be

exhausted.

– Large-diameter hose is effective.

– Water relay remains a possibility.

9

Exterior Stream Position

• Considerations:

– Safety

– Ability to apply water to exposures and

interior of the building

• Preferably will not push fire into uninvolved

areas

9

Nozzle Type

• IC should know the

advantages/disadvantages of nozzles.

• Solid-stream nozzle

– Greatest reach and penetrating ability

– Best suited for attack on main body of the fire

• Variable-stream nozzle

– Fog pattern

– Straight stream

9

Staffing/Apparatus Needs

• Offensive attack: personnel intense

– More fire fighters for hand lines

• Defensive attack: apparatus intense

– Master streams handled by one person

– Pumpers for water supply or drafting

– Tankers for water shuttle operation

9

Conflagrations (1 of 3)

• A fire with major building-to-building

flame spread over some distance

• Departments should recognize the

challenge.

– Determine the probability in their area.

• Special tactics needed

9

Conflagrations (2 of 3)

• Historical

– Rome, London, Constantinople

– Jamestown, Virginia

– Plymouth, Massachusetts

– Boston

9

Conflagrations (3 of 3)

• Recent

– Oakland/Berkeley, California

– San Jose, California

9

Wildland/Urban Interface

• Fires spreading from wildlands into an

urban area, destroying large numbers of

buildings

– Peshtigo, Wisconsin

• October 7, 1871

• Same day as The Great Chicago Fire

• Killed 1200 people (some estimate as many as

2000 fatalities) and destroyed 17 towns.

9

Contributing Factors (1 of 2)

• Closely built structures

• Wood shingle roofs (most often cited

cause)

• Poor water supplies

• Dilapidated structures

9

Contributing Factors (2 of 2)

• Large-scale, combustible construction

projects

• Developments near wildlands

• Built-up areas near high-hazard

locations

9

Group Fires

• Similar to conflagrations

– Fire is confined within a complex or among

adjacent buildings.

– Potential to become conflagrations

– Smaller in scale

9

Strategies and Tactics

• Important to understand how fires

spread

– High convected heat

– Flying brands

– High radiant heat

• Primary means of fire extension

9

Priorities

• Life safety

• Extinguishment

• Evacuating people before they are

threatened is key to success

– Proactive measure

9

Evacuation

• Area must be beyond the secondary

line of defense

– Wide-perimeter should be maintained

• Evacuation should be handled by police

department.

– A police branch in the IMS is a good

organizational tactic at large-scale fires.

9

Water Supply

• Will be challenged by large-fire tactics

• Priorities:

– Water conservation

– Maintaining fire break

– Protecting exposures

9

Tactical Elements (1 of 2)

• Evacuate and rescue people in

imminent danger

• Evacuate people in the endangered

area beyond the secondary line of

defense

• Set up a line of defense with natural or

artificial fire breaks

9

Tactical Elements (2 of 2)

• Establish a secondary line of defense

• Narrow the flame front

• Maintain brand patrol

9

Non-Attack

• Seldom used strategy

• ICs fail to recognize a total loss.

• Used when:

– Environmental concerns are paramount.

– Safe offensive attack is not possible.

– Defensive attack is not practical.

9

Summary (1 of 4)

• Three possible operations at a structure

fire:

– Offensive

– Defensive

– Non-attack

• A proper size-up will indicate which

operation is appropriate.

9

Summary (2 of 4)

• Offensive attack

– Best chance of saving lives and property

– Operation of choice when justified by

proper size-up

9

Summary (3 of 4)

• Defensive attack

– Rarely an effective means of saving lives in

the building of origin.

– May be the IC’s only reasonable option

– Indicated by proper size-up

– Strategic objectives:

• To protect internal and external exposures

while extinguishing the fire

9

Summary (4 of 4)

• Non-attack posture

– May be best option when:

• Offensive attack is not possible

• Building and surroundings are a total loss