Operational Burdens of High-Rise Fire Stairwell Ascends: What the Climb Costs Before the First Drop of Water

Every high-rise fire is governed by a single, unforgiving variable: how fast a firefighter can complete a stairwell ascend in full gear while carrying the tools needed to fight the fire. When elevators fail — whether out of service on arrival, removed by protocol, or lost to heat and smoke during the incident — stairwell ascends become the only way up. The operational burdens that follow are not theoretical. They are measurable, predictable, and severe.

Captain James Davis of the Chicago Fire Department, a 30-year veteran assigned to Engine Company 43, devoted his article in the More Air, More Time FDIC 2025 Supplement — published by Fire Engineering in partnership with the Firefighter Air Coalition — to quantifying those operational burdens. Drawing on decades of fireground experience and published research from the Illinois Fire Service Institute, his work maps the physiological and logistical toll of a stairs-only high-rise response. This overview covers his central findings and sends every chief, company officer, and firefighter back to the full article with a sharper understanding of what the climb demands.

The Weight Firefighters Carry During Stairwell Ascends

Stairwell Ascends

Davis begins with a number that reframes the entire discussion. A firefighter in full personal protective equipment, wearing a self-contained breathing apparatus and carrying a standard complement of hose, forcible entry tools, and a high-rise bag, is hauling roughly 135 pounds of equipment up the stairs during a stairwell ascend. That figure accounts for equipment weight alone — it does not include the firefighter’s own body weight, the cardiovascular demands of the climb, or the thermal burden imposed by encapsulated gear in a warming stairwell.

The severity of the operational burdens during stairwell ascends is governed by three factors Davis identifies: the vertical distance to be covered, the total weight each firefighter is carrying, and the baseline physical fitness of the individuals making the climb. All three variables work against the fire department in a serious high-rise fire, and none of them can be altered once the alarm sounds.

Vertical Response Time and the Cost of Every Lost Minute

Every high-rise fire runs on a timeline, and Davis devotes considerable attention to defining the phases of that timeline in terms that incident commanders can apply.

The period from building entry to the moment water reaches the fire is the vertical response time. When elevators are functioning, this might take three to five minutes. When stairwell ascends are the only means of vertical movement, the vertical response time can stretch to fifteen, twenty, or twenty-five minutes depending on the height of the fire floor and the load each firefighter carries. The fire service has long recognized an operational benchmark of roughly eighteen minutes from arrival to water application, derived from case studies of major high-rise fires worldwide. Exceed that threshold during a prolonged stairwell ascend, and the data reveals a consistent pattern: fire extends beyond the compartment of origin, smoke conditions degrade to the point where interior operations become untenable, and the probability of civilian survival drops steeply.

Davis then distinguishes between two operational phases that shape the entire incident. The first phase — what the fire service often calls the primary reflex — covers everything from building entry through the stairwell ascend to the moment the first-due assignment achieves water on the fire. The second phase — the secondary reflex — is the time required for relief crews, fresh air cylinders, and logistical support to reach the fire floor and sustain uninterrupted operations. If the first crew took twenty minutes to complete their stairwell ascend, the relief crew will also need twenty minutes. The air cylinders being hauled up by the bottle brigade — a process that pulls firefighters away from search and suppression — are subject to the same vertical delay. There is no way to accelerate the secondary reflex without either adding personnel or accepting that the first crew will operate beyond the point where their air supply is sufficient.

What Goes Wrong During a Prolonged Stairwell Ascend

One of the most valuable contributions Davis makes in his article is cataloging the events that can occur while firefighters are still climbing — events that worsen fire conditions, complicate the operation, and endanger everyone inside the building, all while the first-due company is mid-ascent.

Window failure on or near the fire floor is the first vulnerability. Glass fails when exposed to heat beyond its rating, and when it does, fire dynamics inside the compartment change instantly. A broken window introduces oxygen that can trigger or accelerate flashover. It alters the flow path, pulling smoke and heat toward the opening in ways that compromise previously tenable access routes. For crews in the stairwell, a window failure between the lobby and the fire floor can turn a clear stairwell into a smoke-logged vertical shaft, forcing firefighters to don facepieces and consume air earlier than planned — shrinking the working time they will have once they reach the fire floor.

Compromised fire doors are the second vulnerability. High-rise buildings rely on compartmentation to contain fire and smoke within the unit of origin, but compartmentation only functions when doors remain closed and intact. A door propped open, a door that fails to latch because the frame has warped, a door held by a wedge never removed — any of these defeats the passive fire protection the building depends on. Once the stairwell door is compromised, smoke enters the vertical path that every firefighter and evacuating occupant is using. The stack effect amplifies the spread, and firefighters already fatigued from the stairwell ascend must now navigate smoke-filled conditions while their air supply continues to diminish.

Elevator failure is the third vulnerability — and Davis notes that it occurs not as a rare anomaly but as a predictable event roughly fifteen to twenty minutes into a high-rise fire. Even if elevators were operational on arrival, heat, water, smoke, and electrical damage typically disable them during the incident. When the elevators go down after the operation is underway, every resource that was being moved efficiently — personnel, air cylinders, medical equipment — must now be moved through the same stairwell ascends that are already stretching the operation past its limits. The secondary reflex absorbs a second wave of delay at the moment it can least afford one.

These three vulnerabilities interact, and they all share a common accelerant: the time consumed by stairwell ascends. The longer it takes firefighters to reach the fire floor and begin suppression, the more likely each event becomes and the more severe its consequences.

Operational Burdens Lead Back to Air

Davis does not present his findings as an argument against aggressive interior attack. He presents them as an argument for understanding what aggressive interior attack actually requires when stairwell ascends are the only way up.

The central thread running through every operational burden he examines is the finite nature of a firefighter’s air supply. A standard SCBA cylinder provides roughly fifteen to twenty minutes of working time before the low-air alarm activates. That is the entire budget for reaching the fire floor, searching for victims, applying water, and exiting safely.

In a single-story structure at grade, that budget is workable. In a high-rise fire where the fire is on the 27th floor and stairwell ascends are the only path, the arithmetic collapses. Research from the Illinois Fire Service Institute, cited throughout Davis’s article, demonstrated that stairwell ascends produce the highest peak oxygen consumption of any fireground activity — 8.1 METs — and that air consumption rates during these climbs approach 79 liters per minute, nearly double the standard service-time estimate used by NIOSH. The firefighter who reaches the 20th floor has already spent a substantial fraction of their air budget on the climb alone. Their heart rate is approaching 185 beats per minute. Their core temperature is rising. And the fire has had twenty minutes to grow unchecked.

Davis identifies the air standpipe system (Firefighter Air Replenishment Systems / FARS),  as the structural answer that removes air logistics from the list of operational burdens. These fixed, pressurized air distribution systems are built into the building’s infrastructure, running through stairwells and terminating in fill panels where firefighters can refill their cylinders in under two minutes without removing their SCBA or going off air. The bottle brigade disappears. Personnel freed from hauling cylinders can search floors, relieve exhausted attack crews, and support command. The building itself becomes part of the air supply solution.

The codes recognize FARS. The International Fire Code includes it in Appendix L. The Uniform Fire Code addresses it in Appendix F. NFPA standards reference it in Appendix D. More than four hundred jurisdictions across the country have adopted FARS requirements for qualifying structures. The technology exists. The operational case is settled. What remains, as Davis’s article makes plain, is the will to require it.

Preparing for the Stairwell Ascend Before the Alarm Sounds

Davis closes with recommendations that are practical, specific, and within the reach of any department willing to confront the operational burdens of stairwell ascends honestly.

He urges departments to examine their high-rise operational plans and ask whether those plans account for a stairs-only response — and if so, at what cost in vertical response time, air consumed, and personnel committed. He recommends an honest assessment of member physical fitness against the documented demands of a prolonged stairwell ascend under load. He encourages departments to evaluate equipment deployment methods and explore techniques for reducing the weight carried per firefighter during vertical movement. He insists that high-rise contingency training must include stair-only scenarios, because the calls that expose operational gaps are not the ones where everything goes according to plan.

Above all, he asks departments to identify every building in their response area where stairwell ascends during a high-rise fire would outrun the air their firefighters carry. Where the answer is yes — and for most departments with high-rise buildings, it will be — that gap must be documented, formally communicated to municipal leadership, and addressed. The window to solve the air problem is the design and permitting phase. Once the certificate of occupancy is issued, the leverage is gone, and the building will keep its operational burdens hidden until the next alarm reveals them.

Captain Davis has written an essential field guide for understanding what a high-rise fire demands when stairwell ascends are the only path to the fire floor. The full article is available in the More Air, More Time FDIC 2025 Supplement, published by Fire Engineering in partnership with the Firefighter Air Coalition.

Captain James Davis is a 30-year veteran of the Chicago Fire Department assigned to Engine Company 43. He instructs nationally and internationally on mid- to high-rise firefighting strategies and life safety concerns in tall buildings and serves as a technical panel member for the FSRI Study of Fire Dynamics and Firefighting Tactics in Multi-Story Residential Structures.

The Firefighter Air Coalition is the nation’s leading authority on firefighter air safety. Our mission is simple: More Air, More Time. Visit aircoalition.org for training resources, code adoption guidance, and the complete More Air, More Time supplement library.

Resources:

Visit Kitchen Table Resource Center

Read the full article:  Operational Burdens:  The Impact of Firefighter Stairwell Ascends at High-Rise Fires