Lessons From One N.Y. Plaza

Lessons From One N.Y. Plaza

Details of how the fire at One New York Plaza was fought by New York City fire fighters are described for the first time in this article by Chief of Department John T. O’Hagan, who was in charge of operations at the then new office building in Manhattan’s financial district. Previous articles about this fire, regarded as a classic in modern, central-core, high-rise construction, have been concerned with design and construction failings.

On August 5, 1970 at 5:59 p.m., an alarm was transmitted for a fire in a 50-story modern office building at One New York Plaza and ushered in a new era in the annals of fire fighting. It was the first time that a fire initiated by a local source of ignition in a high-rise fireproof building spread with lightning speed to involve two floors and a total of 40,000 square feet of floor area before the arrival of the fire department.

The building was recently completed except for some interior finish and was partially occupied. The fire floors were being prepared for occupancy. Telephones were being installed, floors finished, rugs laid and furniture arranged. Wiring was being installed and ceiling tiles had been removed to expedite the procedure. Before the fire was brought under control two lives were lost, over 50 people hospitalized and there was over $10 million in losses to the structure and its contents. These results were traceable to the building design, the assemblies systems and materials employed and, in some cases, the workmanship. The contributing elements included:

  1. Central core design;
  2. Highly insulated climate control design with locked sash;
  3. Central air conditioning—with common ceiling plenum;
  4. Heat, flame and smoke-sensitive elevator call buttons;
  5. Exterior wall construction;
  6. Spray fireproofing of structural members;
  7. Lack of evacuation procedure;
  8. Workmanship and materials used.

Start of fire

The fire started on the 33rd floor and spread rapidly to the 34th floor. Physical evidence and available testimony indicate that the fire probably started in the southeast corner of the building. At 5:50 p.m., a guard inspecting the 33rd floor discovered smoke coming from an opening in the ceiling. He alerted the other occupants of the floor and they proceeded to the lobby. One of the occupants notified the building management of the fire.

Four men on the 32nd floor detected an odor of smoke and failing to find the source proceeded to the 33rd floor where they were met by heavy black smoke coming from the office space in the southeast corner. At about the same time, another guard on the 35th floor saw heavy black smoke rolling past the windows at the southeast corner. He sounded the building fire alarm and noted the time at 5:59 p.m. This was a local alarm and was not transmitted to the fire department.

At 5:50 p.m., two men working in the lobby were checking the time when they noticed flaming debris and glass falling into the building plaza. They also noted a concentration of smoke in the lobby and proceeded to inquire about the safety of their fellow employees. They agreed that it was at least 10 minutes later before the fire department arrived.

Finally, an employee of 4 New York Plaza seeing flames emitting from two windows on the 33rd floor at the southeast corner, called the fire department. The time was 5:59 p.m.

The last persons known to have been in the vicinity of the fire area were three secretaries who were inspecting their new office. As they proceeded to the 32nd floor at approximately 5:45 p.m., they noticed an odor of smoke but took no action. The ensuing 14 minutes delay in the transmission of the alarm allowed the fire to develop to the extent that it had full possession of the southeast corner of the building generating sufficient heat to fracture two ¼-inch panes of plate glass and vent itself to the outside before an alarm was transmitted. The rapid acceleration of the fire was of, and by, itself unusual.

to Mayor John V. Lindsay.Fire conditions at One New York Plaza, right, are described by Chief John T. O'Hagan

New York Daily News photo, right, and New York Fire Department photo

At left, arrows show how 33rd floor heat and smoke traveled to 34th through open recess in telephone wiring closet floorPlenum area, not involved in the fire, is typical of such areas at One New York Plaza.

N.Y. Fire Dept. photos.

Meanwhile an occupant of the 34th floor noticed smoke in the vicinity of the climate control console at the southwest corner of the building. After verifying the presence of a light smoke condition, he turned to alert some fellow employees and to guide their evacuation. In a matter of seconds, the light haze had changed to a thick black smoke which completely obscured the exterior wall of the building and immediately began to fill the 34th floor forcing a hasty retreat by the occupants via the interior stairs. The time was between 6 and 6:05 p.m.

These actions set the stage for one of the most difficult fires the New York Fire Department has encountered in recent years.

Confusion and misinformation

On their arrival the fire department found a fire of unbelievable proportions issuing from both the east and south sides of the building on the 33rd floor. Shortly thereafter, the windows on the 34th floor virtually exploded, issuing great volumes of fire. Confusion was the order of the day. Reliable information regarding the condition of the building, its systems, its staff or its occupants was unavailable. Rumor and misinformation abounded. From this starting point the battle proceeded and continued for the next six hours.

The first-arriving units, Engine 10 and Ladder 15, under the command of the 1st Battalion, proceeded to the 32nd floorJn elevator car 46 operated by two civilian employees. After discharging the fire forces, the operator pressed the button to return to the first floor. However, the car did not descend, but rather continued upward to the 33rd floor. When the elevator car doors opened, the two occupants were hit with a blast of heat and heavy black smoke. Fortunately, this time the doors closed and now the elevator proceeded to the 36th floor where it stopped. One of the men made his way to the fire tower and finding firemen there, requested their help in rescuing his colleague. Firemen searching the 36th floor located the distressed man and administered resuscitation and first aid prior to removing both men to the hospital for prolonged periods of confinement. Both recovered. Elevator car 46 was now out of service.

Battalion 2 and Rescue 1 attempted to proceed to the fire floor to search two elevator cars that were registered as stalled on the 33rd floor on the elevator console. They used car 36, which was in a bank of elevators servicing the 31st to the 40th floor. They elected to proceed to the 31st floor and walk to the 33rd floor. However, seconds after the elevator left the first floor, it stalled. The chief of the 2nd Battalion reported his predicament via his walkie-talkie radio. There was no immediate way of determining their location because the elevator console registers an “X” when cars that only service upper floors are traveling through the blind shaft of the lower floors. Since they were not in any immediate danger and no resources could be committed to extricate them, they were left to resolve their own predicament. They forced the elevator door, breached the shaft walls and lowered themselves to the fourth floor. Eventually they found a serviceable elevator in the 21st to the 30th floor bank and went to work on the fire floor. In the meantime, precious time and resources were wasted. It was assumed that the insulation on the safety interlocking circuits had been destroyed and the circuit shorted. When this safety system is not completed, elevator car travel stops. For this reason, cars in this bank were not used.

Initially, first-alarm units Engines 6 and 32 and Ladder 10 were able to travel to the 28th floor in an elevator operated by a building service employee. However, he failed to return to the ground floor and because of the malfunction of the cars in the other serviceable banks, a period of approximately 20 minutes elapsed during which time no elevators were available.

Engine 7 was assigned to search interior stairs for distressed occupants. They walked up and encountered people in need of help from the 11th floor and higher levels. They assisted them to safety and when satisfied that the stairs were cleared, made themselves available for fire fighting. At this time, they found an available elevator and proceeded to the 28th floor. Eventually two cars were made continually available, but the delay was costly.

Fire fighting reflex time, the period from the sounding of the alarm until the fire department was operating on the fire, was probably at least 20 minutes. The fire fighting efforts consisted of a direct attack on the fire at its point of origin with 2 1/2-inch hand lines operating from the fire tower and the enclosed stair in the southeast corner of the building. Progress was thwarted at this location by the intensity of the fire as well as the arcing of the high tension power cables in the electrical closet adjacent to the interior halls. Several fire fighters were actually burned while attempting to maintain this position.

Positions reinforced

Due to the length of the stretch, the unavailability of elevators and the necessity to concentrate on rescue operations, only one line was placed in operation by the first-alarm units. Second-alarm units reinforced the original position with two additional lines and also operated from the two interior enclosed stairs at the northeast and northwest end of the core, in an attempt to contain the spread of the fire. These positions were also reinforced by additional lines. While the attack was being pursued, ladder companies searched all floors, stairs, and elevator cars. Ladder 6 walked from the 28th floor to the roof and down again searching each floor and the roof. Under cover of a house line stream, three trapped occupants were located in the elevator cars on the 33rd floor. Car doors were forced, first aid given, and victims removed to safety. One victim survived.

Once control was established on the 33rd floor, third-alarm units began the attack on the 34th floor using the same vantage points and containment strategy. When the floor buckled on the northern end of the building, a deluge set was substituted for hand lines and the companies withdrew to the comparative safety of the enclosed stairs. Each stage of the attack consumed a number of hours and another hour passed before the heat subsided to the point where we could examine the 35th floor closely, even though there was only minor extension at this level.

Structural damage made caution a byword and prolonged the operation considerably. Few of the building’s systems were of any assistance in containing the fire. Fan controls were damaged and although an attempt was made to use them to dissipate the heat, they were ineffectual and too late.

The lesson to be learned from the experience of this fire is that at these elevated locations, fires of this magnitude leave very little opportunity for innovative attack procedures. Ventilation at the location and time that it is desired is difficult to accomplish due to recessed windows, heavy plate glass, the injury potential in the street, untenable environment on the floors above, and the lack of special tools designed to overcome these problems. Fire suppression is limited to a lateral approach at floor level from the enclosed stair in the core, the point where temperatures are the highest. We are currently engaged in designing tools to overcome these difficulties but they are in the development stage and are of limited capacity. These new tools being developed include floor cutters which will cut holes in the fire floor from the floor below the fire to allow the insertion of applicators with fog heads; and lever arms with applicators which, when used from the floor below, will break windows and insert the applicator from the exterior. In the meantime, interior attack from the core under the most adverse conditions of heat remains the simplest and virtually the only strategy available.

Heat: the big enemy

The primary obstacle to the fire fighter in high-rise fires is heat. The fire-resistive construction has always contained heat to a much greater extent than non-fireproof construction. Complete climate control in the newer high-rise construction, with careful consideration to heat transfer, complicates the problem. When we add to these conditions large interconnected fire areas, forced draft from air-conditioning and ventilating systems, and an increase in the flammability of contents, we create the high temperatures, rapid spread and destruction that this fire produced.

At the temperatures encountered, a fire fighter’s effective work time is about 5 minutes. Further exposure reduces him to a nonambulatory casualty requiring the assistance of two or more additional fire fighters whose services are temporarily lost in the control of the fire. Furthermore, it is detrimental to the man’s health and also results in a loss of his services while on medical leave. Consequently, large numbers of companies were called, and the men rotated frequently, to keep injuries to a minimum. Over 50 companies and 300 men were committed at this incident.

The logistics problem was of major concern. Providing adequate manpower, tools, water, breathing equipment, hose, extra compressed air bottles, medical attention and continuous communications, required extensive staff assistance and planning. Additional chief officers were special-called and assigned exclusively to these functions. They kept an adequate supply of resources available until the fire was under control.

The air-conditioning system played a significant role in the severity of the fire and in the horizontal spread. Oxygen supply controls the rate of fire development and the degree of fuel consumption. The best information available indicates that the supply fans of the air-conditioning systems continued to operate until approximately 6 p.m. The forced draft increased the supply of oxygen and the ultimate intensity of fire, leading to the subsequent failure of the double-paned glass windows in the exterior walls and a full supply of oxygen. Following the control of the fire, the initial inspection of the office spaces in the periphery of the building gave the appearance that the area had not been occupied or furnished because there was no residue from the contents. However, closer examination indicated that the incineration of the combustible contents was so complete that it only gave this appearance. Melted metal parts were identifiable and subsequent examination of records helped identify the furnishings and equipment that were present.

Return Air System

The return air system in a building of central core design depends on a common ceiling plenum with connections to one or more return shafts. A slight negative pressure in the shaft will cause a steady flow of air from the occupied spaces within a given floor and in effect, provides one overall fire area. Heat generated in a fire travels by convection into the plenum and is drawn toward the return shafts in the core. With the quantities of heat that are being developed in these fires and with the insulation and limited means for heat dissipation that are available, the heat transfer proceeds at a substantial rate. As the heat accumulates in the plenum, it seeks the points of least resistance in this chamber and finds them in the open return registers located in the ceiling spaces adjacent to the fire area. When this occurs, the blanket of heated air banks down through the register and, being above the ignition temperature of paper, causes ignition to take place at remote locations without flame contact and in the absence of a common source of ignition. At this point In the process, the environment of the high-rise building is introduced and the development of another intense fire is under way. Eventually the individual fires merge and you have a mini-conflagration.

The direction of the heat travel and the path of the fire spread will generally be toward the return shaft in the core which is accepting the air flow from the space involved in the fire. This process was evident at this fire, based upon an examination of the structural damage and the extent and direction of the fire. Although it has been well established that the fire started in the southeast corner of the building, the air flow in the return system and the convection currents generated by the fire were not toward the southeast return shaft. This phenomenon can generally be verified by examining the office spaces in proximity to the shaft.

Distorted beam, which sheared fastening bolts, is one of 133 that were replaced. Arrow points to drop in this floor beam.Gypsum block partition stood in dotted line area before it collapsed, leaving 35-floor drop down shaft

N.Y. Fire Dept. photos.

A reception area adjacent to the shaft was involved in fire and its furnishings did sustain deep charring and heavy damage. However, the fire did not propagate and the areas adjoining it were not involved. One office at the least end of the building was heavily involved. The fire issuing from its windows caught the attention of people of 4 New York Plaza, which led to the transmission of the alarm. This fire did not extend to the next office on the east end of the building and it appears that the actual communication of the fire to the east end was by direct flame contact from the original fire on the southeast corner. There was no structural damage to the floor beams or the flooring at this east end, indicating that the temperature levels in the plenum at this point were not excessive. Even the light metal supports for the ceiling tiles only suffered minor distortion.

The explanation for this effect appears to center on a full cinder block partition that extended from the flooring on the 33rd floor to the underside of the 34th floor and along the south wall of the interior corridor around the core. It was provided to enclose three conference rooms at this location. This partition served as a barrier to the flow of air and convected heat and appears to have diverted the flow toward the west end of the building. It is, indeed, in this direction that the fire traveled, consuming almost the entire south floor area and extending to involve all the interior offices at the west end of the building on the north side. One interior office space was involved.

Furthermore, it was the floor beams in the immediate vicinity of the west end of the core that suffered the most distortion and where the damage to the floor above was the greatest.

It is, therefore, reasonably certain that the central air-conditioning system not only affects the rate of development of the fire and its intensity but also contributes to its extension and helps determine the direction of its spread.

The recirculation of contaminated air can also have detrimental effects on life safety in a building. Products of combustion, including carbon monoxide, can be recirculated until fusible link-actuated dampers close on the openings ,to the return shaft, or until heat or smoke controls on supply or return fans activate. In this fire, the return fan detection devices failed to operate and it was hours before they were shut down. However, the dampers did close when the fusible links melted and this did correct the problem of recirculation in part. In the meantime, however, recirculation did cause serious problems for the occupants until they could be evacuated.

The heavy black smoke described on the 34th floor by the occupants in the vicinity of the air-conditioning and ventilating consoles could also be attributed to the blocks of styrofoam insulation in the exterior walls which were easily accessible to flames and which were totally consumed in the fire.

In any event, whether by direct production or through recirculation, smoke distribution is a problem complicated by central air conditioning. The problem is reduced somewhat by the limited capacity of the ventilation system which is designed to provide something on the order of three changes per hour. If the exchange rates were any higher, they would certainly provide a much greater hazard.

Vertical spread a major problem

Vertical spread was also a major problem at this fire. A universally recognized characteristic of “fireresistive,” “fireproof,” or “Class I” construction is that such buildings will confine fire to one floor unless unusual conditions are present. These would be explosions, renovations in progress, fire doors blocked open or missing, or special shafts or stairways within certain occupancies. The acceptance of “skyscrapers” by the public and by the authorities has been predicated on the belief and assurance that only a limited number of people would be exposed to the perils of a single fire. And that the elevators and stairways need only accommodate a relatively small percentage of the total population of such buildings evacuating the limited area of fire involvement. Also, that only a limited number of fire streams would be needed to control any fire.

One area that was covered in detail was the possibility that fire may have extended to the 34th floor via the air-conditioning ducts. A thorough examination of the ducts, the dampers, and the extension points of the fire eliminated this possibility. All dampers operated properly and vertical ducts were not involved with fire, nor were the shafts. In no location did the pattern of fire spread indicate that the fire extended via ducts or shafts of the air-conditioning system. Vertical fiber glass connections in the periphery airsupply system did play a part. They were not properly firestopped and left spaces of up to 1 ½ inches in the floor openings through which they passed. When subjected to high temperatures, the connections disintegrated leaving 8-inch openings which allowed the passage of fire. The other possible points for the vertical extension of the fire were floor openings for electrical conduits and vertical openings in the exterior walls. Because of the extensive damage sustained in this area, it was impossible to identify conclusively which of the foregoing was the primary artery and, at one time or another, all were probably involved.

Poor pre-fire planning

As mentioned before, one of the obvious problems that existed was the lack of a coordinated notification and evacuation plan. The consequences of the deficiency was mitigated by the low occupancy rate at the time of the fire. If the same conditions developed during normal working hours, the loss of life could have been staggering.

The original discovery was not immediately communicated to the building maintenance and management office, which resulted in a delayed notification of the fire department and of the occupants of the building. There was no coordinated effort to identify the location and confine the fire, and little intelligence available for the fire department on its arrival. There was an absence of a satisfactory evacuation plan and two of the employees who attempted to render assistance made an error, due to lack of experience and training, that cost them their lives.

The only alarm system provided was the one associated with the standpipe system. It consisted of 58 pull lever stations located on the corridor wallnorth side—outside of the standpipe riser stairwell, as well as stations on the roof, in the lobby, in the cellar, and in the second subcellar.

Alarm gongs are located on the roof, 45th floor service corridor, and every 10 floors below. They are also located in the cellar and second subcellar. This system failed to provide a meaningful alert or adequate information regarding the fire.

Structural deficiencies

Other structural features that contributed to the fire problem, but to a lesser degree, were:

Fire-stopping. Fire-stopping is a critical feature of construction and its proper installation requires an appreciation of its functions and its importance by the contractor and the tradesman. It also requires continued surveillance by the building inspector. In this building it was not applied properly around exterior “I” beams, in the exterior walls, around vertical connections in the peripheral airconditioning system, around soil pipes, and in the openings from the ceiling plenum into the power and communication closets.

Sprayed insulation. Sprayed insulation to be effective must be applied on clean steel. From examination of the insulation in both the involved and uninvolved areas, it is apparent that the insulation was applied over rust. This probably contributed to the loss of adhesion and the subsequent beam distortion. In addition, in many locations it was apparent that the insulation had been omitted and/or removed by other tradesmen making their installations and never replaced. There was a wide variance in the consistency of the insulation, as well as its depth. It is apparent that its use requires closer supervision during the application and a re-evaluation of its effectiveness.

Integrity of gypsum block partitions. The gypsum block partitions forming the interior wall of the air-conditioning return shaft collapsed during the fire. Subsequent inspection revealed that it had not been secured on either top or the side and was, in effect, free standing. For each ounce of pressure differential in the shaft, a force of over 2700 pounds is applied to the wall. This, combined with the weakness of the wall, led to its failure. This failure increased the air circulation while the return fans continued to operate, increasing the rate of burning. This condition also creates a hazard potential to occupants or fire fighters who may fall through the opening to their deaths. Every similar partition requires a reinspection.

Floors. The problems created by the “Q” floor construction include thickness and heat insulation capacity. Its qualification for designation as fireresistive is open to question. It transmits heat at a much faster rate than previous floor constructions and intensifies conditions on upper floors.

Windows. The windows were difficult to open, requiring a special wrench for the five locks, four of which are beyond the reach of an average man. They are double-paned, ¼-inch glass and in some instances, the exterior skin of the building failed before the windows. They are most difficult to break from the floor above. Windows of this type should be considered fixed-sash and not allowed credit for ventilation requirements.

Open stairs. The lack of appreciation of the principle of compartmentation, which is basic to the acceptance of a high-rise structure, is best indicated by the open stair from the 35th to the 36th floor. Although this did not lead to fire extension in this area, the potential is present and provides a good indication of the need for the education of engineers, architects, and plan examiners and inspectors.

Floor beams. There were approximately 133 secondary floor beams showing serious distortion which had to be replaced. This was due to the failure of the spray insulation. Floor sagging occurred over wide areas.

Fire loading

Of major importance was the fire loading on each floor. What appeared to be conventional furnishings and a below-average amount of office correspondence and paper storage, proved to emit larger quantities of energy than was anticipated. This appears to have been due to the synthetic cushioning and coverings used in new office furnishings. Materials such as polyurethane foam have varying formulas, and the flammability and heat emission characteristics range over a wide spectrum. In this instance, the materials proved to be so highly flammable that in his report on this fire, W. Robert Powers, superintendent of the New York Board of Fire Underwriters, recommended that they be prohibited from use.

Lessons learned

  1. Central core design accompanied by common ceiling plenums presents a potential for large-area involvement of fire on the upper floors of high-rise buildings that are beyond our previous experience.
  2. Central air conditfoning, if allowed to continue to supply fresh air, will increase the rate of fire development and complicate our problems.
  3. Vertical extension to floors above the fire floor is more likely in the new lightweight fire-resistive highrise construction.
  4. Inductance-type elevator call buttons will register unsolicited calls for the fire floor in the presence of heat, smoke, or flames causing the elevator car to stop and the doors to open. Warping of the shaftway doors may prevent them from closing and occupants of the cars may be trapped. Insulation on interlocking circuits can be damaged by heat, and if shortcircuiting occurs, the travel of the car will be interrupted and the occupants stranded.
  5. Supervised, pre-evacuation planned procedures are a must for high-rise buildings to provide immediate action prior to the arrival of the fire department. A trained building staff is vital.
  6. Spray-type insulation for structural steel members has questionable effectiveness and caution must be exercised at fire situations where it has been used.
  7. Central communication systems for high-rise buildings are essential for evacuation and reports on the status of the occupants and the condition of the building.
  8. New synthetic materials have contributed substantially to the fire loading. They produce highly toxic products of combustion and increase the threat to life safety.
  9. Command procedures are of primary importance, and adequate staff assistance is essential. Control of manpower and rotation of personnel to minimize the effects of the high concentrations of heat are critical.
  10. Smoke distribution throughout the building, seriously threatening the occupants, can take place independently of the air-conditioning system through the “stack effect” and can delay fire suppression efforts.

Reprinted from WNYF Magazine

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