A key responsibility of the first-in officer is to conduct an on the spot analysis or size-up of the situation.   The first responder, be it the first-in company officer, an acting company officers or a chief, is always the incident commander until formally relieved.   A size-up is a rapid mental evaluation of various factors present at an emergency.   Strategic objectives, tactical objectives, and methods will be established based on information gathered during the size-up. The size up is the first building block in the hierarchy of fireground decision-making.


Without a proper size-up, the fire attack can be a hap-hazard operation with no apparent purpose or plan in mind. The operation may degenerate into one where water is simply squirted onto flame wherever it appears.   This results in a larger loss of life and property than when a property planned and managed fire attack is used.   The comparison between size-up versus no size-up is akin to building a house with a set of plans as opposed to building it without a set of plans.


The first-in officer is faced with the need to make proper and reasonable decisions under the immediate pressures of an emergency. A size-up system becomes an important tool to have in this situation. Initial decisions must be flexible and subject to change or modification as the changing fire situation may dictate.


Four systems of size up will be discussed in this section. They are:


*   The Layman system

*   The sequential size up system

*   The four questions method

*   The "SEE FIRE" system


Remember, a size up system is a mental process.  The new officer may want to make up a written checklist.  The experienced officer will probably complete his size-up in his head based upon his knowledge and experience.


The Layman System

The Layman system has five components

  1. Facts
  2. Probabilities
  3. Own situation
  4. Decision
  5. Plan of operation


Under each component of the system, there are a series of factors to consider. They are as follows.


Facts:  (the facts that the situation presents)


*   Time of  the emergency

*   Location of the emergency

*   Nature of the emergency

*   Life hazard

*   Exposures

*   Building or buildings involved

*   Fire

*   Weather

Probabilities:  (predictions based upon the existing situation)


*   Own situation:

*   Life hazard

*   Extension of fire

*   Explosions

*   Collapse

*   Weather changes

*   Preventable damage


Own Situation:            (your resources with which to handle the situation)


*   Personnel and equipment on scene

*   Additional assistance- available

*   Water supply available

*   Private fire protection on site

*   Action already taken


Decision:                                   (results of items 1,2, and 3)


*   Initial decision

*   Supplemental decisions


Plan of Operation:                                         


*   Orders and instructions

*   Supervision of operations







1. ALARM RECEIPT           





               2. EN-ROUTE  






                      3. ON-SCENE ANALYSIS





                                      4. PRIORITY OF FIRE ATTACK




The “Sequential System” is a second system that takes factors to be evaluated and organizes them sequentially, from time of alarm to the setting of strategic priorities.   In other words, “Size-up” begins when the alarm sounds.  The officer must not wait until he arrives at the scene.   He must focus his attention on the job before him as a first responder, rather than being concerned about other matters such as, how the apparatus is being driven.


The following is an outline of the “Sequential Size-up System”.





MODE                                                FACTORS TO BE CONSIDERED



ALARM RECEIPT                            Type of call

Where are we going?

Who's responding?

Water supply/topography


Proprietary systems

Life hazards

Special hazards

Time of day


Fuel type


MODE                                                            FACTORS TO BE CONSIDERED


EN-ROUTE                                       Response routes and arrival times of other units             

Map and preplan review

Visible signs (smoke, etc.)

Types of occupancies nearby

Further information from dispatcher

Access around fire

Hydrants and water

Street width

Exposure distances

What do I know about this place?


Special hazards listed in preplan

Call additional help?




Arrival and on the scene size-up                    What have I got?

Life hazard (factual or possible)

What's burning?

Where's it going?

Type of construction

Path of fire travel

What's in its way?

How fast is it burring?

Heavy fire or just smoke?

Does the exterior appearance indicate the type of interior construction?


MBO Priority of Fire attack                           Analyze safety factors


Extension control


Damage control

Ventilation needed?

Potential need for additional alarms?

Media notified?

Investigator needed?






A “Size-Up System” can be simplified into four (4) questions that pertain to fire travel.









The-"SEE FIRE" Method


This system uses an acronym to allow the first responder to recall strategic priorities in fire fighting and steps in size-up.      The words of the acronym are "SEE FIRE".


SEE stands for:

*   SAVE




These are the strategic priorities, or objectives, that are of concern. These strategic priorities can be disected into the tactical efforts necessary to carry them out.


Regardless of which is selected, a size-up system is a must for the first responder. There needs to be a logical basis for making strategic and tactical decisions. Such a system helps the incident commander to discipline himself to make a size up, even though a critical situation faces him and incoming officers are calling him on the radio and pressing for an assignment.


During the initial size-up, it is necessary to. give a report on conditions to incoming units and chiefs. The incident commander needs to briefly serve as the "television camera". This, will help to perform their size-ups while responding.   Remember, every responding officer needs to perform a size-up, whether he is to be first or fourth in. He needs a picture of what is happening so he can begin to plan. This is not to say that he should anticipate a command, but that he needs to tune in to the incident and begin some planning in his mind.


It is very difficult to respond to an incident, especially one where the smoke can be seen for miles, and not get a report of conditions from the first in officer. The report of conditions should give a snapshot of what is occurring. If possible, it should give some strategic orders to second in companies as well as request additional help if needed.


FIRE stands for: 




*   RISK




*   Path

*   Location

*   Fire-load




*   Extent

*   Speed of fire spread

*   Exposures




*   Occupants

*   Personnel

*   Property




*   Personnel needed

*   Equipment needed




Some examples of reports on condition follow.


As you say these to yourself, time them and you will find that they only take a few seconds to transmit. These reports can help to set the tone for the entire operation.  If the report is clear and concise and the first in officer portrays an air of calmness and professionalism, it will have an effect on other fireground personnel.  When the incident commander is excited and emotional, it seems that other officers (especially newer officers) may also become excited and emotional.


Here are some examples:


“Engine 915” at the scene.   Smoke showing from roof of a 1 story tilt-up industrial building.  Stand by for further report.   “Engine 914” support the sprinkler system.


“Engine 914” at the scene.   Four story brick and wood joist hotel. Smoke and fire showing at 3rd floor windows. We have possible jumpers.   We are committing to rescue.   Give me a second alarm. Engine 915 begin extinguishment Tower 909 handle exterior rescue operations.


Do these radio transmissions paint a good picture for you?  


Yet they only take a few seconds.  The company officer needs to discipline himself to conduct a methodical size-up

and give a good report on conditions.     The report of conditions in all probability will be given while the size-up is

still being conducted.