The Empire State Building (July 28, 1945)
 Jake Pollack BAE Penn State 2011
Keywords: Weather conditions, miscommunication, human error

Abstract

In the early 20th century, there was a boom in skyscraper construction. Each new building was to be taller than the last. The city of New York was one of the cities during this boom that continued to advance in high-rise construction. On March 17, 1930, vertical construction began on the Empire State Building and concluded on November 13 of the same year. The Empire State Building stood at 1,454 feet from ground level to the top of the lightning rod. This made it the tallest building in the world for 41 years until the World Trade Center's Twin Towers were built.

This enormous structure created a large target to hit for a low flying aircraft. On a foggy July day in 1945, a United States Military plane struck the Empire State Building. Weather conditions, miscommunication and human error led to this building failure.


Summary of Events
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Figure 1: B-25 Mitchell Bomber. Source: aerospace.web. Permission Pending.

At approximately 8:55 a.m., on Saturday July 28, 1945, an Army Air Corps B-25 Bomber took off from Bedford, Massachusetts en route to Newark, New Jersey with three passengers aboard. (Levy, Mathys, Salvadori and Mathys 2002). Around 9:30 a.m., the plane was flying over New York City in a dense fog and at 9:40 a.m., crashed into the 79th floor of the Empire State Building. The plane, as seen in Figure 1, weighed approximately ten tons and was flying at 250 miles per hour during impact. One engine continued through the 79th floor, exited out the other side of the Empire State Building and fell through the roof of a neighboring building. The other engine went down an elevator shaft in the building. The gasoline of the B-25 Bomber caught fire on impact and was deemed the cause of 11 of the 14 deaths that resulted from this incident. The other three deaths were from the members aboard this plane who died upon impact. No major structural damage was done to the Empire State Building.


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Figure 3: The location indicated shows where the B-25 Bomber came in contact with the Empire State Building. This picture was adapted from a sketch in the book Why Buildings Fall Down by Levy, Mathys, Salvadori and Woest.

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Figure 2: Empire State Building. Source: mapsofworld.com
Building Description

The Empire State Building is 103 stories, stretches 1,454 feet high and weighs approximately 365,000 tons. There are 6,500 windows, 73 elevators, 10 million bricks, 210 columns and 200,000 cubic feet of Indiana Limestone in this structure (ESBNYC 2010). The masonry façade is supported by steel spandrel beams attached to cast-iron columns. The beams are linked to posts which support the weight of the floor. These beams also extend from the frame to support the weight of the windows and walls for each story (Tauranac 1995). The foundation of the building extends to 55 feet below grade. The Empire State Building can be seen in comparison with neighboring buildings in Figure 2. More building statistics can be found at www.esbnyc.com



Additional Information

In 1945, there were flight rules stating that any aircraft flying over New York City had to maintain an altitude of 2,000 feet (Scott 2007). Due to the dense fog, the pilot of the B-25 bomber was having great difficulty maintaining visibility. In order to gain greater visibility the pilot decided to fly lower to the ground, not realizing that he was flying into downtown Manhattan. The pilot had to fly below 1,000 feet to see the ground and as he descended to this altitude he almost hit the Chrysler Building. As he swerved away from the Chrysler Building he crashed into the north side of the Empire State Building (History.com). The location of the impact can be seen in Figure 3.



Fire Protection

The original fire-detection system in the Empire State Building consisted of call boxes on each floor that made a “bong” sound when manually activated. In the event of a fire, the “bong” noise would sound corresponding to the story that the fire was on. For example, if the fire was on the fourth floor, the fire-detection system would sound four times.
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Figure 4: Section of the 8" concrete covering on each column.


All structural steel was protected by iron oxide and linseed oil paint, which was applied at the steel mill in order to prevent corrosion. The steel was then covered with an asphalt coat, which was applied in order to protect the steel when it came in contact with concrete. All steel columns were enclosed in cinder concrete for additional fire-proofing and column strengthening (Penafiel, 2006). This can be viewed in Figure 4.

The Empire State Building’s water delivery system was state-of-the-art at the time of installation. The water tanks were inside the building rather than on the roof. This provides seventy miles of piping to deliver water to the entire building (Penafiel, 2006). Despite the initial intensity of the explosion, the standpipe system exhausted most of the fire within 35 minutes of the crash. Fireproof stairwells were required for all high-rise buildings in 1930. The fireproof stairwell in the Empire State Building saved the lives of hundreds of people during this near-catastrophe (Scott 2007).

The Empire State Building is compartmentalized and each floor is self-contained. Each floor and each room are separated by fire partitions. Each story utilizes its own heating and cooling ducts. It also has its own elevator and utility shafts which are enclosed by thick masonry walls. These features make it difficult for fire to spread throughout the building.



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Figure 5: Diagram showing where the plane entered the building and the flight paths of the two plane engines. Diagram adapted from a drawing in Why Buildings Fall Down by Levy at al.
Damage and Debris

Once the plane crashed into the Empire State Building three separate fires started. The engine that traveled straight through the Empire State Building continued through the roof of a neighboring 12-story building creating a fire. The other engine fell down an elevator shaft in the Empire State Building and started a fire within the shaft. The elevator fire ignited the plane's fuel, which had spread throughout the 78th and 79th floors on impact. It resulted in 11 of the 14 deaths (Levy, et al 2002 and Scott, 2007). A diagram of the point of the contact and the path that the two engines traveled can be seen in Figures 5 and 6.

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Figure 6: This image shows how the B-25 Bomber entered the Empire State Building

Figure 5 shows how the plane entered the Empire State Building and the path the engines followed after impact. As seen in Figure 6, the left wing and the body of the plane penetrated the building façade while the right wing hit the building and sheared off.

The majority of the damage created from this crash was done to the façade of the building which absorbed most of the plane's impact. Most structural components remained intact; however, bent girders needed to be replaced, the building needed to be resealed and both the 78th and 79th floors needed to be reconstructed. This crash caused $1 million in damages in 1945. This translates to just under $12 million in 2010 based on inflation.




Casualties and Injuries

There were 14 deaths and 26 injuries resulting from this incident. Six of the 20 present National Catholic Welfare Conference employees died immediately on impact and died instantly at their desks. More workers tried to escape, but succumbed to flames in their efforts. One woman was thrown through a window by the blast and fell to her death. One man, fearing he had no way to escape the flames, jumped from his window and struck a ledge a few stories down and died. A janitor lost his life while trapped by fire on the 78th floor, and another man fell to his death down an elevator shaft following the blast (Scott 2007).

An office worker near the crash site named Catherine O’Connor recalled the events from this disaster: “The plane exploded within the building. There were five or six seconds—I was tottering on my feet trying to keep my balance—and three-quarters of the office was instantaneously consumed in this sheet of flame. One man was standing inside the flame. I could see him. It was a co-worker, Joe Fountain. His whole body was on fire. I kept calling to him, ‘Come on, Joe; come on, Joe.’” Fountain managed to escape both the fire and the building, but died days later in the hospital because his injuries were too severe.
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Figure 7: Photograph of the Coast Guard helping injured civilians following the B-25 Bomber crash. Source:aerospace.web. Permission Pending.


The other three deaths were the pilot and two passangers on the B-25 Bomber. Though these 14 deaths were devastating, this disaster could have been much worse. Because the events happened on a Saturday there were roughly 1,500 workers within the building. However, on a normal week day there were usually about 15,000 workers in the building. Additionally, the 78th floor is used solely for mechanical equiptment and storage space therefore limiting its occupancy (Scott, 2007).

For each tragic death there was an amazing survival story to match it. The most incredible tale of survival belonged to a 20-year-old elevator operator named Betty Lou Oliver. Oliver had just opened the door to her elevator as the blast occurred. The explosion threw Oliver across the hall where she was found by two other women. Badly burned, Oliver was treated with first aid by these women and helped into another elevator in order to reach additional medical care. As the elevator descended the cables snapped and the elevator began to plummet towards the ground. An emergency hydraulic braking system slowed the plunging car as severed cables acted like a coiled spring to slow the elevator to a less sudden halt at impact with the ground. All of the women were injured and shaken up, but still alive. At ground level they were helped immediately by Coast Guard first aid pharmacists (Scott, 2007). Figure 7 shows a photograph taken on July 28, 1945 in the Empire State Building. In the photograph a woman is being helped by the Coast Guard and other nurses.

For more accounts of survival and other information please visit http://www.aerospaceweb.org/question/history/q0311.shtml.


Investigation

Many people ask why the Empire State Building did not collapse, while the World Trade Centers did during the September 11, 2001 attacks.

The B-25 bomber weighed approximately 10 tons and was flying approximately 250 miles per hour. See Figure 8 for plane dimensions. The kinetic energy released from this collision was approximately 45,500,000 ft-lb and the plane traveled approximately 66 feet into the building. Upon impact, a 69,000 lb force on the Empire State Building (Delatte 2009). The Empire State Building utilized a portal frame depending on rigid beam-to-column connections to resist lateral loads (Nair, 2007). Upon impact the building shook as debris began to fall from the building. However, the structure did not displace drastically because of the relatively low weight of the aircraft in relation to the building. The damage caused by the plane was done mostly to the masonry façade creating limited structural damage. As stated above, the cost of the damages was roughly $1 million. Bent girders needed to be replaced, and the damaged floors had to be reconstructed and re-sealed (Scott, 2007).

The World Trade Centers (1 and 2) were struck by Boeing 767 jet airliners. See Figure 9 for plane dimensions. These planes weigh 15 times the amount of a B-25 bomber and were traveling at twice the speed upon impact. Due to large increase in speed and weight the planes traveled deeper into the building and struck the structural core of World Trade Centers 1 and 2.
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Figure 9: Wingspan: 156'-1" Height: 64'-7" Length: 156'-2" Photograph and information obtained from Boeing.com.

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Figure 8: Wingspan: 67'-6" Height: 16'-9" Length: 53'-0" Photograph and information obtained from nationalmuseum.af.mil
Fuel used in the B-25 is called avgas, a high octane
gasoline, while the 767 planes used Jet-A, a derivative of kerosene that fuels all commercial jet airliners (Scott 2007). Jet fuel burns at much higher temperatures than B-25 Bomber fuel thereby releasing much more energy within the structure. The B-25 had limited fuel because it only had enough for the short trip from Massachusetts to New Jersey. The 767 planes had full fuel tanks which are approximately 35 times the size of the B-25 Bomber's fuel tanks. In the Empire State Building, the fuel had exhausted itself within 35 minutes of the crash, while the fuel burned much hotter and longer in the World Trade Centers. This caused the already weakened structural core to fail and the buildings to collapse.


More information about the collapse of World Trade Centers 1 and 2 can be found here. The World Trade Centers 1 and 2 wiki discusses the September 11, 2001 terrorist attacks and their effects on the twin towers.

Had the B-25 Bomber been carrying bombs that could have detonated upon impact, then this accident could have been catastrophic. Depending on the types of bombs that this aircraft may have been carrying, the Empire State Building could have received much more extreme damage, raining shrapnel down on the city and perhaps even collapsing. This potential collapse would kill thousands, if not millions of people. Luckily this bomber was not carrying bombs on this flight (Scott, 2007).



Lessons Learned

Freak accidents can occur at any time for numerous reasons. This collision shows why it is always good to be prepared. The B-25 Empire State Building collision provides a great example of how fireproofing systems can and should work and how important they are to a building.

The Empire State Building took many precautions during the design phase of the building pertaining to fire protection. The building had a compartmentalized structure so that fire could not spread, each floor had its own heating and cooling ducts and each room was separated by fire partitions. This building also utilized a fire stairwell that saved hundreds of lives. These precautions taken by the designers of the building saved the lives of many and also helped save the building from further damage.

In the event of a fire it is never safe to use an elevator. Instead, stairwells should always be used because mechanical equipment and other mechanisms which rely on electricity are not dependable. However, this account does show the success of an emergency braking system in elevators. Betty Lou Oliver can attest to this.

There is a reason why planes were not to fly lower than 2,000 feet above New York City. The pilot of the B-25 Bomber was instructed to land in New York Municpal Airport (now called LaGuardia Airport), but the pilot ignored the warning. Human error was the major factor causing this disaster. Had the pilot listened to warnings and not flown into downtown Manhattan, this tragedy could have been avoided. Following this crash, the Air Force began strictly enforcing flight rules and created mandatory training for pilots who transition from combat flying to domestic flying (Scott, 2007). Also, flight rules over New York City were strengthened to prevent this from occurring again. Nonetheless, an almost identical incident occurred less than one year later as a plane got lost in the fog over New York City and crashed into 40 Wall Street. A U.S. Army Air Force C-45 Transport Plane en route to Newark, NJ crashed into the building at approximately 8:10 p.m., killing its crew of four (Alexander, 2007).

Worthington, Skilling, Helle & Jackson was the structural engineering firm that designed World Trade Center's Twin Towers. Due to the plane crashes at the Empire State Building and 40 Wall Street, the structural engineers accounted for blast resitance in the design for the Twin Towers. This is why the towers did not collapse upon impact. However, their design did not account for a fuel fire. The fuel fire burned at an extremely hot temperature, which melted structural members and ultimately led to the collapse of the towers. More detailed information about this building failure can be found here.



Conclusions

This collision could have easily been avoided, had the pilot observed the local flight rules in New York City. However, in spite of his foolish behavior, the casualties – to both the building and its inhabitants – were limited and reasonably well contained. By including state-of-the-art safety features, the Empire State Building’s designers safeguarded the structural integrity of the building against potentially catastrophic effects. And, quite fortunately, a great number of additional casualties were avoided because the collision occurred early in the day during the weekend instead of a busy weekday when ten times more people would have been present.

Pilots must learn from previous mistakes. For this incident to happen twice in the span of one year is unacceptable. Pilots must be extremely cautious in undesirable weather conditions, especially fog. If given a warning, then it is probably warranted. If it is recommended that the pilot should land based on the future safety of civilian lives then he or she must adhere to this advice. Pilots may be confident in their abilities, but must follow local flight rules and heed the advice of air traffic controllers.


Bibliography


ABC News. (July 28, 2010). "Empire State Building Sustained Crash - ABC News." ABCNews.com. <**http://abcnews.go.com/US/story?id=92525&page=1**> (Sept. 23, 2010).
This article explains the logistics of the plane crash. It goes into detail about the conditions during the time the plane struck the building and specifics following the crash.

No Author Listed. "Bomber Crash into Empire State Building."NSDL Materials Pathway.<**http://matdl.org/failurecases/Building Cases/Bomber.htm**> (23 Sept. 2010).
This article goes more in depth on the mathematical and physical impacts that the plane had on the building. It provides approximate values for velocities, weights and forces of the crash.

Delatte, Norbert J. (2009). “Beyond Failure: Forensic Case Studies for Civil Engineers.” Aircraft Impacts.ASCE Publications. 38-41.
This text explains that the lives lost in this accident were due to gasoline fires and not by the impact of the B-25 bomber that hit the building. It further explains the mathematics and physics behind the crash as well.

Esbnyc.com. “Empire State Building Facts.” Empire State Building : Official Internet Site. Web. 11 Nov. 2010. <**http://www.esbnyc.com/tourism/tourism_facts.cfm?CFID=40025537&CFTOKEN=48719984**>.
This is the official website for the Empire State Building. This site provided various facts about the building that were useful for this wiki.

History.com. "Plane Crashes Into Empire State Building." History.com — History Made Every Day — American & World History. <**http://www.history.com/this-day-in-history/plane-crashes-into-empire-state-building**> (23 Sept. 2010).
In this article, History.com explains about the extent of the crash and compares its relevance to today’s standards.

Levy, Matthys, Mario Salvadori, and Kevin Woest. (2002.) “Why Buildings Fall Down.” How Structures Fail. New York: W.W. Norton. 24-30. (23 Sept. 2010).
In this text there are diagrams showing the exact point of entry into the building and the location of debris resulting from the crash. It explains the impact and path of the plane and said debris.

Nair, Rshankar. "You Can Never Know Too Much." Www.arcplusonline.com (2007): 2-4. Web.
This journal provided insight to the lateral system of the Empire State Building.

NYC-Architecture.com. "New York Architecture Images- Empire State Building." Nyc-architecture | New York Architecture- Historic and Contemporary.<**http://www.nyc-architecture.com/MID/MID073.htm**> (23 Sept. 2010).
This article goes in depth about the extravagance of the Empire State Building and its contributions in the world of architecture. It also explains the effect of the crash on the building.

Penafiel, Karen. "The Empire State Building: An Innovative Skyscraper." Buildings | Facility Managers, Commercial Building Resource | Www.buildings.com. June 2006. Web. 11 Nov. 2010.<http://www.buildings.com/ArticleDetails/tabid/3321/ArticleID/3180/Default.aspx>.
This website provides information about the fireproofing in the Empire State Building.

Petroski, Henry. (2006) “Success through Failure: the Paradox of Design.” Princeton: Princeton UP. 110, 125-127. (23 Sept. 2010).
Petorski writes about the Empire State Building pre-crash including its impact on the city and the world. He also explains how it was the tallest building in New York for over 30 years until the World Trade Centers were constructed.

Richman , Joe. 28 July 2008. "The Day A Bomber Hit The Empire State Building : NPR." NPR : National Public Radio : News & Analysis, World, US, Music & Arts : NPR. <**http://www.npr.org/templates/story/story.php?storyId=92987873**> (23 Sept. 2010).
NPR provides the reaction of people involved in the accident and how they were affected. These accounts give more detail as to the conditions of the day and the impacts on their lives.

Scott, Jeff. "Aerospaceweb.org | Ask Us - B-25 Empire State Building Collision." Aerospaceweb.org | Reference for Aviation, Space, Design, and Engineering. 17 June 2007. Web. 11 Nov. 2010. <http://www.aerospaceweb.org/questions/history/q0311.shtml>.
Aerospace web provides various quotes from the day of the event as well as an in depth analysis of the events leading up to and after the plane crash.

Tauranac, John. The Empire State Building: the Making of a Landmark. New York: Scribner, 1995. Print.
This text gives in depth information about fire protection and structural systems regarding the Empire State Building.

Additional Resources

http://www.aerospaceweb.org/question/history/q0311.shtml

http://www.boeing.com/commercial/767family/specs.html

http://docs.google.com/gview?url=http://www.arcplusonline.com/papers/7009.pdf&chrome=true

http://www.mapsofworld.com/travel-destinations/empire-state-building.html

http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=476