Truss Roof, Possible Victim, One Engine
At 03:47 you, a lieutenant, are first to arrive at a fire in a 60-foot-wide, one-story strip of eight retail units in a 1970s shopping center. Heavy smoke is pushing from the front of unit 3 and from the rear of units 3 and 4. The roof is 2x10 parallel-chord truss with plywood sheathing under a 20-year-old membrane. A police officer says he saw someone enter unit 3 about ten minutes ago. You have three firefighters and 750 gallons. Ladder 2 is four minutes out; Engine 2 is six minutes out. The nearest hydrant is 300 feet away, 52 psi static on a 6-inch main. No sprinklers. The roof over unit 4 is visibly sagging at the parapet and fire is showing through the soffit.
1. State your initial action plan and your mode of attack, and justify it against the survivability and collapse indicators you have.
Read the worked answer
Declare a working fire, take command, and plan an offensive attack on unit 3 with a pre-committed transition to defensive - not an offensive firefight across the whole building.
The case for offensive: one story, fire confined to units 3 and 4, heavy smoke indicating a fire that has not yet vented through the roof, and a reported occupant. Early water on the seat can still make this a room-and-contents fire.
The case for caution, and it is stronger: parallel-chord truss, 20 years old, plywood sheathing, no sprinklers, and visible sagging at the parapet over unit 4 with fire through the soffit. That last indicator is not speculation - it is the roof telling you it has been burning. Lightweight truss fails as a system, usually without warning, and typically in the 10-to-20-minute window from ignition. The report is already ten minutes old.
Initial plan:
- 300 feet of supply to the hydrant, but do not let the lay consume the crew; 750 gallons on board is the working water for the first two minutes.
- One 1¾-inch line to the front door of unit 3, straight stream, coordinated with vertical ventilation only if a ladder company can do it from outside the collapse zone. No unvented interior advance.
- No entry into unit 4. Fire through the soffit means the cockloft is involved; that is a defensive problem, not an interior one.
- Establish a collapse zone at least equal to the wall height beyond the parapet, and keep police and bystanders out of it.
The honest framing: I am offensive on unit 3's front third and defensive on everything behind it. If I cannot get water on the seat of the fire in the first two to three minutes of arrival, I pull everyone out.
2. How do you handle the "possible victim" report alongside the truss and roof conditions? What are your trigger points?
Read the worked answer
Treat the report as credible but degraded, and buy the search with time, not with depth.
A ten-minute-old sighting of someone entering a heavily smoke-filled store with a truss roof is a low-probability survivability profile. That does not make the search optional - it makes the depth and duration of the search the decision.
Search parameters:
- Search the front third of unit 3 only - entry area, aisles, and the first bays near the door - off a charged line, two-person teams, with a wall of water available before anyone commits.
- Absolutely no search of unit 4 or anything under the sagging roof section.
- A rapid intervention crew must be in place before the search team commits. Engine 2 arrives in six minutes. If the search cannot wait for a RIC, that is itself an argument for a fast grab by the attack crew rather than a wide-area search.
- Search on the way in, not on the way out. The window is short.
Trigger points that end the interior operation:
- Fire through the roof or a visible increase in smoke velocity and heat at the door.
- Any change in the parapet line, new sagging, or the sound of truss movement.
- No knockdown within two to three minutes of water application - the "two rules": if you have not knocked it down and you are not making the room, you leave.
- Loss of water or a supply problem.
- Failure of PAR within five minutes.
Personally hold the accountability point. The officer at the door with the line is the one who decides the search team's depth, and the chief who arrives later will not be able to see what you can see. Make the call early and make it once.
3. What do you communicate, to whom, and at what points, from arrival through the first ten minutes?
Read the worked answer
Communication is the control measure that keeps this from becoming a mayday. Script it.
Arrival report, before you leave the rig: "Command to dispatch, 1400 block Main, one-story strip center, heavy smoke from units 3 and 4, working fire, possible occupant in unit 3, lightweight truss roof, Main Street Command, give me a full first alarm and a second alarm." Two alarms on a strip center with a possible victim and a truss roof is not panic - it is buying the RIC and the water you will not otherwise have.
To the incoming companies, on arrival: "All companies, operating on channel 2. Truss roof, visible sagging over unit 4 - do not commit past unit 3. Collapse zone is 20 feet off the parapet. Ladder 2, I need vertical ventilation over unit 3 from the exterior only, and a ladder to the roof edge only if the roof is sound. Engine 2, water supply from Commerce and Second, then a RIC at the A/B corner before you do anything else."
To the crews inside: the attack team and the search team hear the same words: front third only, off the line, and the trigger points. State the PAR interval out loud - "PAR every five minutes starting now" - so it is not a habit that stops when the fire gets busy.
When you transition: an explicit, unambiguous order on the tactical channel - "All units, we are going defensive, everybody out of the structure, PAR now." Not "let's back out" or "pull the lines." Then account for every member by name before the master streams start.
The most common failure in this scenario is not a bad tactic; it is two crews operating under two different mental pictures. One channel, one picture, repeated out loud.