Fireground factors offer a standard list of basic items command must consider in the evaluation of tactical situation. This list should provide command with a "check list" of the basic items that are involved in size-up, decision making, initiating action, review and revisions on the fire ground.
The effective command officer soon learns that he can only deal with a limited number of factors of any kind on the fireground. Within the framework of that limitation, the identification of the critical factors is extremely important. All the factors are
Not critical in any one tactical situation. Command must identify the critical fireground factors that are present in each tactical situation - the list of factors offers a framework for that process.
Many times we begin operations before adequately considering the critical fireground factors. Size-up is a conscious process involving the very rapid but deliberate consideration of the critical factors and the development of a rational plan of attack
Based on those conditions. Attack is many times an instinctive action-oriented process that involves taking the shortest and quickest route directly to the fire. Action feels good in
Fireground situations while thinking delays actions; but beware of non-thinking attack situations and non-thinking attackers.
Fireground factors represent an array of items that are dynamic during the entire fireground process and the relative importance of each factor necessarily changes throughout that time frame. Command must continually deal with these changes and base
Directions on factor information that is timely and current. Beware of developing an initial plan of attack and sticking to that same initial plan throughout the fire, even though
Conditions continue to change. Effective fire operations require attack plan revisions that continually reconsider fireground factors based upon information feedback.
In critical fire situations, command may develop an initial plan and initiate an attack based on an incomplete evaluation of fireground factors. In such cases, he must continue throughout the operation to improve the information he bases his decisions upon. He will seldom operate with complete information during initial operations.
The effective management of each fireground factor requires command to apply a somewhat different form of information management.
Most tactical situations represent a complex problem with regard to how command deals with fireground factor information. There are factors that can be determined from his operating position on the outside of the structure and other factors that can only be determined from other operating positions - both outside and inside the structure. Fireground intelligence available to command is developed utilizing an overlapping variety of these information factors and forms. These forms of information revolve around the three following basic factors:
Visual factors - these factors include those obvious to visual observation and those absorbed subconsciously. This visual information is categorized as the type that can
Normally be gained by actually looking at tactical situation from the outside. This form of intelligence involves the perceptive capability of command.
Reconnaissance factors - these factors include information that is not visually available to command from his position on the outside of a tactical situation and must be gained by actually sending someone to check out a situation and advise command of findings. This generally involves command making a specific assignment and then receiving an information-oriented report.
Preplanning and familiarity factors - these factors include the intelligence that is gained from formal prefire planning and by general informal familiarization activities. Such intelligence increases the information initially available to command from the outside of a tactical situation. This information arms command with intelligence that he would normally gave to assign as a reconnaissance factor or do without.
Building
Tactical priorities identify the three separate tactical functions that must be completed in order to stabilize any fire situation - these priorities also establish the order in which these basic fireground function must be preformed.
These functions should be regarded as separate, yet interrelated, activities which must be dealt with in order. Command cannot
Proceed on to the next priority until the current function objective has been completed.
Basic tactical priorities are as follows:
1 - RescueRescue - the activities required to protect occupants, remove those who are threatened and to provide treatment for the injured.
2 - Fire Control
3 - Property Conservation
Fire Control - the activities required to stop the forward progress of the fire and to bring the fire under control.
Property Conservation - the activities required to stop or reduce additional loss to property.
The objective of each priority are reflected in the following bench marks of completion:
1 - Rescue - Primary Search (all clear)All three tactical priorities require somewhat different tactical approaches from both a command and an operational standpoint.
2 - Fire Control - Under Control
3 - Property Conservation - Loss Stopped
While command must satisfy the objective of each function in its priority order, he must, in many cases, overlap and "mix" the activities of each to achieve the current bench mark. Notable examples are the frequent need to achieve interior tenability with active/extensive fire control efforts before getting on with primary search, or the need to initiate salvage operations while active fire control efforts are being extended.
It is standard operating procedure to extend a primary search in all involved and exposed occupancies which can be entered. Command must structure initial operations around the completion of the primary search. Primary search means companies have quickly gone through all affected areas and verified the removal and/or safety of all occupants. Time is the critical factor in the primary search operations must necessarily be extended quickly and during initial fire stages.
The rescue functions that follow lengthy fire control activities will be regarded tactically as presenting a secondary search. Secondary search means that companies thoroughly search the interior of the fire are after initial fire control and ventilation activities have been completed. Secondary search should preferably be completed by different companies than those involved in primary search activities. Thoroughness, rather
Than time, is the critical factor in secondary search.
The completion of the primary search is reported utilizing the standard radio reporting term " all clear ". It is the responsibility of command to coordinate primary search assignments, secure completion reports from interior companies and to transmit the "all clear" report to command.
The stage of the fire becomes a critical factor that affects the rescue approach developed by command. The following items outline the basic command approach to fire stages:
In nothing showing situations or in very minor fire cases that clearly pose no life hazard, command must structure a rapid interior search and report "all clear". (The interior search for victims will also verify no fire).
In smoke showing and working fire situations, fire control efforts must be extended simultaneously with rescue operations in order to gain entry and control interior access to complete primary search. In such cases, command and operating companies must be aware the operation is in a rescue mode until primary search is complete, regardless of the fire control required. In working fire situations, primary search must be followed by a secondary search.
In cases of fully involved building or sections of buildings, immediate entry and primary search activities become impossible and survival of occupants is improbable. Command must initially report fully involved conditions and that he will not report an "all clear". As quickly as fire control is achieved, command must structure what is in effect a secondary search for victims.
Command and operating companies cannot depend upon reports from spectators to determine status of victims. Control forces should utilize reports as to the location, number and condition of victims as supporting primary search efforts and must extend and complete a primary search whenever entry is possible.
Command must consider the following factors in developing a basic rescue size-up:
1 -Number, location and condition of victimCommand must make the basic rescue decision:
2 -Affect the fire has on the victims
3 -Capability of the control forces to enter the building, remove/protect victims and control fire
Do we remove the victims from fire ? or do we remove the fire from the victims ?
In some cases, occupants are safer in their rooms than moving through contaminated hallways and interior areas. Such movement may also impede interior firefighting.
Command must realistically evaluate the manpower required to actually remove victims and then treat their fire-affected bodies. In cases involving such multiple victims, command must call for the timely response adequate resource and quickly develop an organization that will both stabilization the fire and provide for the removal and treatment of the occupants.
Rescue efforts should be extended in the following order:
1 - Most Severely ThreatenedCommand must make specific primary search assignments to companies to cover specific areas of large-complex occupancies and maintain ongoing control of such companies until the entire area is searched. When primary search companies or team(s) to continue to cover the interior positions that have been vacated.
2 - The Largest Number (Groups)
3 - The Remainder of the Fire Area
4 - The Exposed Areas
All initial attack efforts must be directed toward supporting rescue efforts and hose lines must be placed in a manner to control interior access, confine the fire, and protect avenues of escape. Hose line placement becomes a critical factor in these cases and command and all operating companies must realize that the operation is in a rescue mode. It may be necessary to operate in a manner that writes-off the structure in order to buy rescue time.
Normal means of interior access (stairs, halls, interior public areas, etc.) should be utilized to remove victims wherever possible. Secondary means of rescue (ladders, fire escapes, life lines, nets, etc.) must be utilized in their order of effectiveness.
Command must structure treatment of victims after removal. Multiple victims should be removed to one location for more effective treatment. Command should coordinate and utilize paramedic capability wherever available and provide emergency medical services as required.
Once the primary search has been completed and an "all clear" transmitted. Command must maintain control of access to the fire area; beware of occupants (and others) re-entering the building.
The most urgent reason for calling additional alarms is for the purpose of covering life safety - command must develop a "realistic" rescue size-up as early as possible.
The term "search and rescue" should be used when structuring a primary search over the radio; "all clear" should be used only as a completion report.
It is standard operating procedure to attempt to stabilize fire conditions by extending wherever possible an aggressive well-placed and adequate offensive interior fire attack effort and to support that aggressive attack with whatever resource and action is required to reduce fire extension and to bring the fire under control.
A critical command decision (both initial and on-going) relates to the offensive/defensive mode of the situation:
Many times offensive/defensive conditions are clear cut and command can quickly develop a decision that relates to that mode. In other cases, the situation is marginal and command must initiate as offensive interior attack, while setting up defensive positions on the exterior. The affect of the interior attack must be evaluated and the attack abandoned, if necessary. Mode changes can develop almost instantly or can take virtually all night. You may have to change your mode to a combination, offensive/defensive attack. This strategy embodies a vigorous attack against the main body of the fire, while taking adequate measures to control actual and potential extension of fire. Your major portion of the fire force operates directly on fire extinguishment problems and a lesser force on fire extension problems. Command must be aware and responsive to such mode changes.
Command must consider the most dangerous direction and avenues of fire extension particularly as it affects rescue activities, confinement efforts, and exposure protection. He must then allocate resource based upon this fire spread evaluation.
In some cases, the most effective tactical analysis involves an evaluation of what is not burning rather than what is actually on fire. The unburned portion represents where the fire is going and should establish the framework force fire control requirements.
Offensive fires should be fought from the interior-unburned side (interior capability is the principal offensive strategy factor).
Initial attack efforts must be directed toward supporting primary search - first attack must go between the victims and the fire and protect avenues of escape.
Determine fire location and extent before starting fire operations. Do not operate fire streams into smoke .
Command can not lose sight of the simple and basic fireground reality that at some point the fire forces must engage the fire and fight. Command must structure whatever operations are required to put water on the fire. The rescue/fire control/extension/exposure problem is solved in the majority of cases by a fast, strong, well-placed attack.
Effective fire control requires that water is applied directly on the fire or directly into the fire area. A direct attack is made on the seat of the fire on the immediate area involved in the fire. (Fire streams can be bounced off roofs and operated into smoke all night and the fire will progress until it runs out of fuel). Command must establish an attack plan that overpowers the fire with actual water application.
The offensive strategy is the strategy most commonly employed since, upon arrival, most fires are of rather small extent or can be attacked directly before the fire spreads. Its greatest virtue is that all problems are solved at one time, life safety, confinement, and extinguishment.
Where fires involve concealed spaces (attics, ceiling areas, construction voids, etc.) it becomes very important that ladders be placed and roofs/ceilings be opened up and assigned companies operate fire streams into such areas. Early identification and response to concealed space fires can save the structure. Officers who hesitate to open up because they do not want to beat up the building many times must attempt an hour later to hold the fire to the neighborhood of origin.
Command must consider six sides (or operational areas) of the fire: front, back, two sides, top and interior.
Where the fire is sizeable, establish a safe and remote position to begin operations from - then move in on the fire.
The basic variables relating to attack operations involve:
Time becomes an extremely important factor with regard to attack operations. The bigger the attack, the longer it takes to get it going; the more interior the attack is positioned, the longer it takes.
Command must balance and integrate attack size and position with fire conditions and his resources.
Tactical realities many times require that pure placement principles are violated. Such violations generally relate to the factor of time versus pure placement. When such principles are violated, command must implement back-up action to cover the "uncovered" area(s). Lacking direction, when fire is showing, companies will many times lay hose and put water on the fire utilizing the fastest, shortest, most direct route.
Attack from the burned side generally will drive the fire, smoke and heat back into the building and the interior fire control forces out of the building.
The fastest place to put water on the fire is generally from the outside at the point where the fire is burning out of the building - the very worst application point most of the time.
When fire is burning out of a building and not affecting exposures, let it burn out, and extend any interior attack from the unburned side. It is usually venting in the proper direction. It requires discipline on the part of control forces to do so.
Command must develop a fire control plan of attack that first stops the forward progress of the fire and then brings the fire under control. In large complex fires, command will not immediately have adequate resources to accomplish all of the attack needs he faces - at that point, he must prioritize attack efforts, act as a resource allocator and determine the response he will eventually require. Accurate forecasting of conditions by command becomes critical during this initial evaluation process.
Command must develop critical decisions that relate to cut-off points and must approach fire spread determinations with pessimism. It takes a certain amount of time to "get water" and the fire continues to burn while the attack gets set up. Command must consider where the fire will be when attack efforts are ready to actually go into operation if he misjudges, the fire may burn past his attack/cut-off position. Do not play "catch up" with a fire that is burning through a building: project your set-up time, write-off lost property and get ahead of the fire. Set up adequately and over power it.
Do not put water into burned property, particularly when there is unburned property left to protect. Many fire streams are directed into property that is already lost, many times at the expense of exposed unburned property. Write-off property that is already lost and go
On to protect exposed property based on the most dangerous directions of spread. Do not continue to operate in positions that are essentially lost.
A defensive/offensive mode
may be used as a "holding action" to keep the fire within reasonable bounds
while awaiting the availability of additional companies that are called
or units at the fire that will shortly become available upon completion
of the initial assignments. At such time an offensive attack can be initiated.
The decision to operate in a defensive mode indicates only that the offensive attack strategy has been abandoned for reasons of personnel safety and the involved structure has been conceded as lost (written off).
The announcement of a change to a defensive mode will be made as "vacate and attack" and all personnel will withdraw from the structure and maintain a safe perimeter. "Vacate and attack" will also be sounded on the fireground by using the multiple long blasts of the apparatus air horns and radio communications. Sector, sides and operational area officers will account for the safety of all personnel.
Interior lines will be withdrawn and repositioned when changing to a defensive mode. Lines should not be operated directly into doorways or windows but should be backed away to positions which will protect exposures.
All exposures, both immediately and anticipated, must be identified and covered. The first priority in defensive operations is to protect exposures.
The second priority may be to knock down the main body of fire. This may assist in the protection of exposures but does not replace it as a first priority.
When exposure is severe and water is limited, the most effective tactic is to put the water on the exposure.
Once exposure coverage is established, attention may be directed to knocking down the main body of the fire. The same principles of large volume procedures should be employed.
It shall be standard procedure to commit whatever fireground resource is required to reduce property loss to an absolute minimum. The activities that relate to effective property conservation require the same early and on-going command functions and aggressive action as both rescue and fire control. All members are expected to perform in a manner that continually reduces loss during fire operations.
When the fire is out, shut down the fire streams. Early recognition that the forward progress of the fire has been stopped is an important element in reducing loss. The earlier the salvage operations begin, the smaller the loss.
When basic fire control has been achieved, command must commit and direct companies/units into "stop loss" activities generally include:
Commit the same overall and sector, sides and operational area command resource to property conservation activities as were devoted to rescue and fire control.
Be aware that personnel involved in rescue and fire control operations are generally fatigued by the time property conservation functions must be completed - this can result in sloppy work and many injuries. Evaluate the condition of personnel and replace with fresh troops if needed.
Prompt fireground lighting, both interior and exterior, reduces fire loss and increases safety.
The provision of salvage functions must be integrated into the cause determination phase. When fire control becomes stable, back fire control companies out and let fire investigators develop a plan. Beware of personnel who want to quickly shovel
Out the interior and go home - they will generally shovel out the evidence with the debris .
Most fire personnel are more
attracted to active fire attack functions than to the less active operations
that relate to property conservation - simply, most firefighters would
rather operate nozzles than throw salvage covers. Command must integrate
effective follow-up to insure minimum property loss. (Such fire attack
inclinations are healthy, beware of firefighters who would rather throw
covers than operate hose lines .)
The following items represent an index of the tactical effectiveness of hose lines:
Hose lines should be advanced inside fire buildings in order to control access to halls, stairways, or other vertical and horizontal channels through which people and fire may travel.
Basic hose lines placement:
Use the size of hose line that will eventually be required from the beginning; if you need a big line provide it from the outset. If there is any doubt from the beginning go to the next size hose line. When you make a decision on what size fire stream to apply, select the size that is actually required. Beware of automatically going for the size you use most often; or the size that is fastest/easiest-we tend to rely on one size of fire stream.
When you change commitment from offensive to defensive and pull hand lines out of the fire building, do not continue to operate them as handlines - convert them to exterior master streams. Give priority to water supply and application. The operating
Positions of such streams must also be evaluated - do not continue to operate into burned property.
Fire control forces must consider the characteristics of the fire streams:
Offensive attack activities must be highly mobile - as their movement slows down, the necessarily become more defensive in nature and affect.
Offensive attack positions should achieve an affect on the fire quickly-consequently, back-up judgements should also be developed quickly. If you apply water to an offensive attack position and the fire does not go out - react; back it up or move on. Beware of hose lines that have been operated in the same place for long periods. Fire conditions change during the course of fire operations (most things will only burn for a limited time) and the affect of hose lines operation must be continually evaluated. If the operation of such lines becomes ineffective, move, adjust, or redeploy them.
Beware of the limitations of operating nozzles through holes. The mobility of such streams is necessarily limited and it is generally difficult to evaluate the effectiveness of such streams. Sometimes you must breach walls, floors, etc., to operate - realize the limitations of such situations.
Consider that hose lines pump as much air as they pump water (particularly fog streams). Think of them as fans when making line placement judgements and use the fan characteristics in a manner that provides for confinement and reduces loss. When entering basement fire(s), do not open nozzles until you can see and are near the fire, if you commit crews to inside operations, do not operate exterior streams into the same building. Do not combine interior and exterior attacks in the same building. It may be necessary to coordinate pulling crews out of the building while an exterior heavy stream knockdown is made. Know when to shut down nozzles - many times continuing operations of large streams prevents entry and complete extinguishment.
Do not operate fire streams into smoke - fire location must be determined before water can be effectively applied. If you use an exterior stream, use a big one. Straight bore tips provide better penetration for heavy streams.
Hand line companies should not engage in laying any more hose than they require to operate their own lines except for standard multiple line evolutions.
The more pumped water, the higher the overall attack capability. Have attack lines ready during forcible entry operations. Attack crews should be fully protected and supervised before forcible entry is effected.
Company officers must assume responsibility for the effectiveness of their fire streams. Such officers must maintain an awareness of where fire streams are going and their affect and report the general operational characteristics back to command. Do not apply water to the outside of a roof and think you are extinguishing the fire . Such water application may offer effective exposure protection; but, if part of the roof is intact, it will shed water just like it was built to do and will prevent water from reaching the seat of the fire. This is particularly true of ladder pipe operations. Do not operate fire streams down ventilation holes hurting offensive operations .
Apparatus function should regulate placement. Many times we reverse this rule by virtue of poor placement, limiting the options or eliminating functions we can assign to that unit.
Firefighters operate with a natural inclination to drive the apparatus as close to the fire as possible. Many times this results in positioning of the rigs that is both dysfunctional and dangerous. The placement of all apparatus on the fireground should be a reflection of one of the following:
Avoid tailboard bumper placement of the fireground. Later arriving companies and personnel should hold positions, stage a minimum of one block short of the immediate fire area and remain uncommitted until ordered into action by command. Units should select standby positions with a maximum of tactical options.
In some large, complex and lengthy fireground operations additional alarm companies should be staged together in one location under the command of a staging officer consistent with level ii staging procedures. Under these procedures, command communicates directly with the staging officer for additional resources.
On the fireground everyone wants to hold a line of their own - be aware of who has water from the standpoint of type of company position and function.
Command must maintain an awareness that access equals tactical options and that the immediate fire area can quickly become congested with apparatus. He must regard apparatus on the fire ground in two categories:
Command, sides and all operating units should attempt to maintain an access lane down the center of streets wherever possible.
Think of fire apparatus as an expensive exposure: position working apparatus in a manner that considers the extent and location of the fire and a pessimistic evaluation of fire spread and building failure. Anticipate the heat which may be released with structural collapse. Apparatus should generally be positioned at least 30 feet away from involved buildings, even with nothing showing. Greater distances are indicated in many situations.
Beware of putting fire apparatus in places where it cannot be repositioned easily and quickly - particularly operating positions with only one way in and out; i.e., yards, alleys, driveways, etc.
Beware of overhead power lines when positioning apparatus. Do not park where lines may fall.
If apparatus does become endangered, operate lines between it and the fire while you reposition it. When you do move it - move it to a position that is safe. It is dysfunctional to move a truck several times throughout the progress of a fire.
Take maximum advantage of good operating position and "build" the capability of units assigned to these effective positions. Initial arriving pumpers should be placed in "key" positions. These positions should offer maximum fire attack access to the fire area and be supplied with adequate supply lines as quickly as possible.
Subsequent arriving companies can operate the hose lines from this apparatus. Place these "key" companies first - before they are "buried" by later arriving units.
Key tactical positions should be identified and engines placed in those locations with a strong water supply.
Take advantage of the equipment on apparatus already in the fire area instead of bringing in more units. Connect extra lines to pumpers which already a good supply line.
Fire hose soon limits the general access as the fireground operation gets older. Command and sides must get apparatus well-placed positions. Lines should be laid with attention to the access problem they present.
Spot the command vehicle in a manner that will allow maximum visibility of the fire building and surrounding area and the general effect of the companies operating on the fire. Command vehicle position should be easy and logical to find and should not restrict the movement of other apparatus.
Ambulances and rescue vehicles should be spotted in a safe position that will provide the most effective treatment of fire victims and firefighting personnel while not blocking movement of the apparatus.
Tactical support activities are those functions that assist active fire control and rescue operations. They generally include forcible entry, ventilation and the provision of access.
Most confusion on the fireground is the result of lack of such support functions and activities. Command must cause these support functions to be completed in a timely and effective manner - he must support the end of the nozzle. We lose often because of a lack of support, not a lack of water.
You ventilate a building principally for these reasons:
The timing of ventilation
becomes important and must be coordinated with fire attack activities -
ventilation should be provided in advance of attack lines. Portable radio
communications between ventilation and command; command and attack facilitate
this interaction.
Fire will naturally burn out of holes in roofs, regardless if you cut the hole or if the fire does. If the fire burns through the roof (defensive ventilation) it will generally do so in the best location-directly over the fire. Locate ventilation holes in a manner that will support rescue activities and fire confinement. If vent holes are cut in the wrong place, the fire will naturally be channeled to them and expand loss.
When you cut a hole in a roof, cut a big one (at least 4' x 4') rather than several small ones.
Do not operate hose lines down ventilation holes. Be cautions of hose lines to roofs when fire and smoke come out vent holes. Operate roof lines only for the purpose of protecting personnel and external exposures.
Effective topside ventilation will tend to keep roofs intact longer and roof condition necessarily becomes extremely important to ventilation activities. If crews cannot get on the roof to ventilate because of advanced fire, command had best begin to react in marginal offensive/defensive terms. Hose line crews can probably get inside and stay inside longer than vent crews can stay on the roof.
The use of positive pressure ventilation provides a safe and effective method of attack mode ventilation. When entry is impractical due to fire and smoke conditions ppv should be utilized prior to entry.
Forcible entry involves a trade-off in time versus damage; the faster you force - the more damage you do. The more critical the fire, the less important forcible entry damage becomes and vise versa. If the fire is progressing and you must go in and attack from the unburned side, don't waste time; force entry.
The provision of access many times will determine if the fire is cut off and extinguished or not. These access-oriented activities generally involve pulling ceilings, opening up concealed spaces and voids, and the activities required to get fire attack efforts in to operate on hidden fire. Such operations beat up the fire building and must be done in a
Timely, well-placed manner. In such cases, do not hesitate - if you size up fire working inside a concealed space, get ahead of it, open up and cut it off.
Beware of the premature opening of doors, holes, access efforts, etc.., before lines are placed and crews are ready to go inside. Good timing requires effective communication between operational functions and command.
The decisions required to provide for adequate resources are an important factor in effective fire forecasting. Command must balance the tactical problems with the resource required to control those problems and stay ahead of the situation. Beware of "crisis management": situation grows at a rate faster than the response rate to that situation - command ends up with an out of control situation and inadequate resource to control it.
Many times command will reach a point where he begins to debate with himself to call another alarm or not - in such cases call for it. Always opt for the extra in the "should I or shouldn't I" stage. If the extra resource is not needed, it can easily be put back in service.
It is the continuing responsibility and function of command to determine the resource required to control the situation and to provide for the timely call for any additional resource required. The early call for additional resource will tend to consistently save the day.
Command must be aware of both the capability and response time of additional resource and effectively integrate these facts into calls for additional resource.
Some tactical situations move slowly, while some move very quickly. Command must call for additional resource at a rate that stays ahead of the fire. Some situations require the categorical call for additional alarms open knowledge of particular characteristics or conditions; in other situations, command will initiate some fire control activities, ask for reports, and based upon receipt of bad news, will strike more alarms.
As command calls for additional
resource, he must build a corresponding command organization-structure
to manage that additional resource. Command cannot encounter a big fire
situation, call additional alarms and then expect to effectively manage
that additional resource in a single alarm command mode.
An actual or potential fire situation exists and the life hazard exceeds the rescue capabilities of initial alarm companies.
The number, location and condition of actual victims exceeds the rescue and removal capabilities of companies.
An actual or potential fire situation exists and the property protection demand (both internal and external) exceeds the fire control capabilities of initial alarms companies.
Fire conditions become more severe or the situation deteriorates significantly.
All companies have been committed and the fire is not controlled.
Forces are depleted due to exhaustion or injury or are trapped or missing: command must forecast the affect the fire will have personnel and provide for the support of such personnel in advance.
Command runs out of some resources (men, apparatus, water, equipment, command, etc.)
There is evidence of significant fire but companies are unable to determine location and extent.
Companies cannot effectively perform early salvage operations.
Situation becomes so widespread/complex that command can no longer effectively "cope" - the situation requires larger command organization and more operational functions.
Command instinctively feels the need to summon additional resource-(do not disregard fireground hunches)
Weather conditions also play a part in additional resources. Hot, humid and cold weather all lead to early depletion of a firefighter's physical capabilities.