Friday, September 9, 2011


B-25 Empire State Building crash

Crash by a U.S. Army B-25 bomber on July 28, 1945
Accident summary
DateJuly 28, 1945
TypeControlled flight into terrain(building)
SiteEmpire State BuildingNew York City
Fatalities14 (11 in building and 3 crew)
Aircraft typeB-25 Mitchell
Aircraft nameOld John Feather Merchant
OperatorU.S Air Force
Tail number41-30577
Flight originNewark, New Jersey

Date:July 28, 1945
Location:New York, New York
Aircraft:North American B-25D bomber
Flight No:N/A
Fatalities:3 : 3 +11

A U.S. Army Air Forces B-25 crashed into the 79th floor of the Empire State Building in New York in heavy fog. The crash killed both crew members and eleven people in the building.




Within 10 seconds of the onset of its destruction -- when none of the rubble had yet reached the ground -- most of the South Tower was already reduced to dust and shredded steel.

Later that day not even plane impacts were necessary to level skyscrapers -- as simply being in the vicinity of the World Trade Center was sufficient to level Building 7.!:--

Photographs of Building 7 prior to its collapse show only small areas of fire.

In under seven seconds Building 7 was transformed from a skyscraper to a tidy rubble pile

 In fact Building 7 was separated from the North Tower by Building 6 and Vesey Street. A photograph of its north facade taken in the afternoon shows isolated small fires, and not even a single window was broken.

Sampoong Department Store collapse

The Sampoong Department Store (삼풍백화점三豊百貨店collapse was a structural failurethat occurred on June 29, 1995 in the Seocho-gu district of SeoulSouth Korea. The collapse is the largest peacetime disaster in South Korean history – 501 people died and 937 were injured.
Sampoong Department Store collapse
DateThursday, June 29, 1995
Time5:52 PM KST
LocationSeoulSouth Korea
501 dead
937 injured

Civil engineering experts were invited to inspect the structure, with a cursory check revealing that the building was at risk of collapse; the National Geographic documentary series Seconds From Disaster indicates that the facility's manager was examining the slab in one of the restaurants on the fifth floor, eight hours before the collapse, when, unknowingly, vibration from air conditioning was radiating through the cracks in the concrete columns and the floor opened up.
Five hours before the collapse, the first of several loud bangs was heard emanating from the top floors, as the vibration of the air conditioning caused the cracks in the slabs to widen further. Amid customer reports of vibration, the air conditioning was turned off, but the cracks in the floors had already widened to 10 cm.
At about 5:00 p.m. Korea Standard Time (UTC+9:00), the fourth floor ceiling began to sink, resulting in store workers blocking customer access to the fourth floor. According to Seconds From Disaster, the store was packed with shoppers 52 minutes before the collapse, but the owner did not close the store or carry out repairs at that time. When the building started to produce cracking sounds at about 5:50 p.m., workers began to sound alarms and evacuate the building, but by then it was too late.
Around 5:57 p.m., the roof gave way, and the air conditioning unit crashed through into the already-overloaded fifth floor.[1] The main columns, weakened to allow the insertion of the escalators, collapsed in turn, and the building's south wing pancaked into the basement. Within 20 seconds, all of the building's columns in the south wing gave way, trapping more than 1,500 people and killing 501.
The disaster resulted in about 270 billion (approximately US$216 million) worth of property damage.


In terms of structural system the twin towers departed completely from other high-rise buildings. Conventional skyscrapers since the 19th century have been built with a skeleton of interior supporting columns that supports the structure. Exterior walls of glass steel or synthetic material do not carry any load.  The Twin towers are radically different in structural design as the exterior wall is used as the load-bearing wall. (A load bearing wall supports the weight of the floors.) The only interior columns are located in the core area, which contains the elevators.

 The outer wall carries the building vertical loads and provides the entire resistance to wind.

The wall consists of closely spaced vertical columns (21 columns 10 feet apart) tied together by horizontal spandrel beams that girdle the tower at every floor. On the inside of the structure the floor sections consist of trusses spanning from the core to the outer wall.

                            BEARING WALLS AND OPEN FLOOR DESIGN

When the jet liners crashed into the towers based upon knowledge of the tower construction and high-rise firefighting experience the following happened: First the plane broke through the tubular steel-bearing wall. This started the building failure. Next the exploding, disintegrating, 185-ton jet plane slid across an open office floor area and severed many of the steel interior columns in the center core area. Plane parts also crashed through the plasterboard-enclosed stairways, cutting off the exits from the upper floors. The jet collapsed the ceilings and scraped most of the spray-on fire retarding asbestos from the steel trusses.  The steel truss floor supports probably started to fail quickly from the flames and the center steel supporting columns severed by plane parts heated by the flames began to buckle, sag, warp and fail. Then the top part of the tower crashed down on the lower portion of the structure. This pancake collapse triggered the entire cascading collapse of the 110-story structure. 

                                                                STEEL FRAMING

            The most noticeable change in the modern high-rise construction is a trend to using more steel and shaping lightweight steel into tubes, curves, and angles to increase its load bearing capability. The WTC has tubular steel bearing walls, fluted corrugated steel flooring and bent bar steel truss floor supports.  To a modern high rise building designer steel framing is economical and concrete is a costly material. For a high-rise structural frame: columns, girders, floors and walls, steel provides greater strength per pound than concrete.  Concrete is heavy. Concrete creates excessive weight in the structure of a building. Architects, designers , and builders all know if you remove concrete from a structure you have a building that weights less. So if you create a lighter building you can use columns, girders and beams of smaller dimensions, or better yet you can use the same size steel framing and build a taller structure. In News York City where space is limited you must build high. The trend over the past half-century is to create lightweight high buildings. To do this you use thin steel bent bar truss construction instead of solid steel beams.  To do this you use hollow tube steel bearing walls, and curved sheet steel (corrugated) under floors. To do this you eliminate as much concrete from the structure as you can and replace it with steel.  Lightweight construction means economy. It means building more with less. If you reduce the structure’s mass you can build cheaper and builder higher. Unfortunately unprotected steel warps, melts, sags and collapses when heated to normal fire temperatures about 1100 to 1200 degrees F.

Interior wall studs made with light-gauge steel

            The fire service believes there is a direct relation of fire resistance to mass of   structure. The more mass the more fire resistance. The best fire resistive building in America is a concrete structure. The structures that limit and confine fires best, and suffer fewer collapses are reinforced concrete pre WWII buildings such as housing projects and older high rise buildings like the empire state building, The more concrete, the more fire resistance; and the more concrete the less probability of total collapse. The evolution of high- rise construction can be seen, by comparing the empire state building to the WTC.  My estimate is the ratio of concrete to steel in the empire state building is 60/40. The ratio of concrete to steel in the WTC is 40/60.  The tallest building in the world, the Petronas Towers, in Kula Lumpur, Malaysia, is more like the concrete to steel ratio of the empire state building than concrete to steel ratio of the WTC.  Donald Trump in New York City has constructed the tallest reinforced concrete high-rise residence building.

File:World Trade Center Building Design with Floor and Elevator Arrangment.svg


File:Wtc floor truss system.png

File:WTC bathtub east.JPG
                       South Tower and slurry wall "bathtub" under construction in 1969

World Trade Center under construction in 1971

The towers were designed as framed tube structures, which provided tenants with open floor plans, uninterrupted by columns or walls. This was accomplished using numerous closely spaced perimeter columns to provide much of the strength to the structure, along with gravity load shared with the core columns. The elevator system, which made use of sky lobbies and a system of express and local elevators, allowed substantial floor space to be freed up for use as office space by making the structural core smaller. The design and construction of the World Trade Center twin towers involved many other innovative techniques, such as the slurry wall for digging thefoundation, and wind tunnel experiments. Construction of the World Trade Center's North Tower began in August 1968, and the South Tower in 1969. Extensive use of prefabricated components helped to speed up the construction process. The first tenants moved into the North Tower in December 1970


A plane that only weighted 10 tons struck the Empire State Building and the high-octane gasoline fire quickly flamed out after 35 minutes. When the firefighters walked up to the 79 floor most of the fire had dissipated. The Empire State Building in my opinion, and most fire chiefs in New York City, is the most fire safe building in America. I believe it would have not collapsed like the WTC towers. I believe the Empire State Building, and for that matter any other skeleton steel building in New York City, would have withstood the impact and fire of the terrorist’s jet plane better than the WTC towers. If the jet liners struck any other skeleton steel high rise, the people on the upper floors and where the jet crashed may not have survived; there might have been local floor and exterior wall collapse. However, I believe a skeleton steel frame high rise would not suffer a cascading total pancake collapse of the lower floors in 8 and 10 seconds. Hopefully some engineer using computer calculations, can reconstruct the effects of a 767 jetliner crashing into another New York City high building. In any other high rise in New York City, I say,

 the floors below the crash and fire, would not

 collapse in such a total a cascading pancake cave-

in.  Most of the occupants and rescuers killed in the

 WTC tower collapse were on the lower floors.


           Perhaps builders should take a second look at the Empire State Buildings construction. There might be something to learn when they rebuild on ground zero. The empire state building has exterior Indiana limestone exterior wall, 8 inches thick. The floors are also 8 inches thick consisting of one-inch cement over 7 inches of cinder and concrete. All columns, girders and floor beams are solid steel covered with 1  to 2 inches of  brick terracotta and concrete. There is virtually no opening in the floors. And there are no air ducts of a HVAC heating cooling and venting system penetrating fire partitions, floor, and ceilings. Each floor has its own HVAC unit. The elevators and utility shafts are masonry enclosed. And for life safety there is a 4-inch brick enclosed so-called “smoke proof stairway”. This stairway is designed to allow people to leave a floor without smoke following them and filing up the stairway. This is accomplished because this smoke proof stairway has an intermediate vestibule, which contains a vent shaft. Any smoke that seeps out the occupancy is sucked up a vent shaft.

                                                        CONCRETE REMOVAL

             Since the end of WWII builders designed most of the concrete from the modern high-rise constriction. First concrete they eliminated was the stone exterior wall. They replace them with the “curtain walls of glass, sheet steel, or plastics. This curtain wall acted as a lightweight skin to enclose the structure from the outside elements. Next the 8-inch thick concrete floors went. They were replaced with a combination of 2 or 3 inches of concrete on top of thin corrugated steel sheets.
 Next the masonry enclosure for stairs and elevators were replaced with several layers of sheet rock.

  Then the masonry smoke proof tower was eliminated in the 1968 building code. 
It contained too much concrete weight and took up valuable floor space.  
Then the solid steel beam was replace by the steel truss. And finally the concrete and brick encasement of steel columns girders and floor supports was eliminated.  A lightweight spray-on coating of asbestos or mineral fiber was sprayed over the steel. This coating provided fireproofing. After asbestos was discovered hazardous vermiculite or volcanic rock ash substance was used as a spray-on coating for steel. Outside of the foundation walls and a thin 2 or 3 inches of floors surface, concrete has almost been eliminated from high-rise office building construction. 

If you look at the WTC rubble at

ground zero you see very little concrete and lots of

 twisted steel.


           How did lightweight high-rise construction evolve since WWII?  It evolved with the help of the so-called performance code. After WWII the builders complained about   building codes. They said they were too restrictive and specified every detail of construction. They called the old building codes “specification codes”.  They complained the codes specified the size and type and some times even the make of a product used in construction. They decried the specification code as old fashion. They wanted the building codes changed to what they called “performance codes.” They wanted the building codes to specify the performance requirements only; and, not specify the size and type of building material to use. For example, with fire resistive requirements they wanted the code to state just the hours of fire resistance (one, two, three or four hours) required by law; and not to state the specific type and material used to protect structural steel and enclosures for stairways and elevators shafts. For example, a performance building code states: the steel has to be protected against heat of flames for one, two, three or four hours during a fire. It does not state what to use as a fire resisting material. This performance code signaled the end to concrete encasement fire protection and allowed a spray on fire protection for steel and plasterboard enclosed stairs and elevator shafts.  Builders hailed the New York City building code of 1968 as a good performance code. 

However, some fire chiefs decried it as a law that substituted frills for real construction safety. 

The asbestos spray on coating of steel trusses used in the WTC towers was considered by Chief of the New York City Fire Department, at the time, John T. O’ Hagan to be inferior to concrete encasement of steel. Writing in his book, High Rise Fire and Life Safety. l976, he listed the following problems of spray-on fire protection of steel:
  1. Failure to prepare the steel for spray-on coating adhesion. Rust and dirt allowed spray-on fire retarding coating to scale and fall away from steel during construction
  2. Poor or uneven application of the spray-on fire retarding was discovered during post fire investigations
  3. Variation of spray-on material during manufacture makes it ineffective
  4. Lack of thoroughness in covering the steel during application is a problem
  5. Failure to replace spray-on material dislodged by other trades people performing work around the steel during the construction of the building.
           The WTC started construction in the 1970s. And the WTC towers built by the Port Authority of New York did not have to comply with the minimum requirements of the new1968 performance building code.




  • The steel columns, girders and floor beams should be encased in masonry or other  more effective fire retarding material. Spray-on fire retarding is ineffective. Post fire investigations reveals the spray on fire retardant has scaled off and steel beams and concrete and steel floor slabs crack and allow flame spread.

  • Lightweight bar joists should not be used to support floors in high-rise buildings. The National Fire Protection Association has shown unprotected steel bar joist fail after five or ten minutes of fire exposure.

  •  For life safety in high-rise buildings bring back the smoke proof tower. This allows people to escape fire using smoke free stairways.

  •  Stairs and elevator shaft ways should be enclosed in masonry to prevent smoke spread.

  • Heating ventilation and air condition HVAC systems should be provided by unit system serving only one or two floors. Central air system serving 10 or 20 floors creates shaft ways and duct systems that penetrate fire rated floors walls partitions and ceilings. Smoke spreads throughout ducts of central HVAC systems.
  • The high rise building framework should be skeleton steel framing not center core steel column framing. There should be no bearing wall high rise construction. Reduce the size of open floor design.
  •  Increase the thickness ofoncrete in floor construction. The two or three inches of concrete over corrugated steel fails during most serious high rise fires and must be replaced.
  • Automatic sprinklers should protect all high rise buildings. Firefighters can extinguish approximately 2,500 square foot of fire with one hose line. Two hose steams may quench 5,000 square feet of fire. The World Trade Center floor areas were 40,000 square feet in area.
  • Federal, State and Port Authority buildings should comply with New York City building codes and actually in some cases should exceed them. Remember building codes are only minimum standards.


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                               El Al Flight 1862

On 4 October 1992, El Al Flight 1862, a Boeing 747 cargo plane of the Israeli airline El Al, crashed into the Groeneveen and Klein-Kruitberg flats in the Bijlmermeer (colloquially "Bijlmer") neighbourhood (part of Amsterdam Zuidoost) of Amsterdam, the Netherlands. Due to the location in the Bijlmermeer, the crash is known in Dutch as the "Bijlmerramp" ("Bijlmer disaster"). A total of 43 people were killed, consisting of the plane's crew of three and a non-revenue passenger in a jump seat, plus 39 people on the ground. Many more were injured.[1][2][3][4]

Boeing 747–200 of El Al

From Wikipedia, the free encyclopedia
El Al Flight 1862

               Aftermath of the disaster.

File:Bijlmerramp2 without link.jpg

Accident summary
Date 4 October 1992
Type Mechanical failure
Site Amsterdam Zuidoost
Passengers 1
Crew 3
Injuries 11 serious, 15 minor (on ground)
Fatalities 43 (4 on board, 39 on ground)
Survivors 0
Aircraft type Boeing 747-258F
Operator El Al
Tail number 4X-AXG
Flight origin 
JFK Int'l Airport
, New York City, USA
Stopover Amsterdam Schiphol Airport
Amsterdam, The Netherlands
Destination Ben Gurion Int'l Airport
Tel Aviv, Israel
Coordinates: 52°19′8″N 4°58′30″E







structural weakness caused collapse of WTC like a pack of cards?i think so


Rwandair plane crashes into airport buildingBY WOLFGANG H. THOME | NOV 12, 2009when a CRJ aircraft, leased from Kenya’s Jetlink to Rwandair, rammed into a building at the airport.Both pilots were also injured, and in particular the First Officer appears to have been trapped in the smashed cockpit for a while – no information is available right now over the status of his injuries. Thankfully, the aircraft did not catch fire

[2]Pilot Crashes Into Texas Building in Apparent Anti-IRS SuicideThursday, February 18, 2010The FBI identified the pliot as Joseph Stack, a 53-year-old software engineer. Stack was confirmed dead, but his body has not yet been recovered.


The Plane That Crashed Into the Empire State Building

On the foggy morning of Saturday, July 28, 1945, Lt. Colonel William Smith was piloting a U.S. Army B-25 bomber through New York City. He was on his way to Newark Airport to pick up his commanding officer, but for some reason he showed up over LaGuardia Airport and asked for a weather report. Because of the poor visibility, the LaGuardia tower wanted to him to land, but Smith requested and received permission from the military to continue on to Newark. The last transmission from the LaGuardia tower to the plane was a foreboding warning: "From where I'm sitting, I can't see the top of the Empire State Building."
The Crash
At 9:49 a.m., the ten-ton, B-25 bomber smashed into the north side of the Empire State Building. The majority of the plane hit the 79th floor, creating a hole in the building eighteen feet wide and twenty feet high. The plane's high-octane fuel exploded, hurtling flames down the side of the building and inside through hallways and stairwells all the way down to the 75th floor.
Confronted with dense fog, Smith dropped the bomber low to regain visibility, where he found himself in the middle of Manhattan, surrounded by skyscrapers. At first, the bomber was headed directly for the New York Central Building but at the last minute, Smith was able to bank west and miss it. Unfortunately, this put him in line for another skyscraper. Smith managed to miss several skyscrapers until he was headed for the Empire State Building. At the last minute, Smith tried to get the bomber to climb and twist away, but it was too late.
The Crash
At 9:49 a.m., the ten-ton, B-25 bomber smashed into the north side of the Empire State Building. The majority of the plane hit the 79th floor, creating a hole in the building eighteen feet wide and twenty feet high. The plane's high-octane fuel exploded, hurtling flames down the side of the building and inside through hallways and stairwells all the way down to the 75th floor.
World War II had caused many to shift to a six-day work week; thus there were many people at work in the Empire State Building that Saturday. The plane crashed into the offices of the War Relief Services of the National Catholic Welfare Conference. Catherine O'Connor described the crash: [blockquote shade="no"] 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." He walked out of it.2 Joe Fountain died several days later. Eleven of the office workers were burned to death, some still sitting at their desks, others while trying to run from the flames.
One of the engines and part of the landing gear hurtled across the 79th floor, through wall partitions and two fire walls, and out the south wall's windows to fall onto a twelve-story building across 33rd Street. The other engine flew into an elevator shaft and landed on an elevator car. The car began to plummet, slowed somewhat by emergency safety devices. Miraculously, when help arrived at the remains of the elevator car in the basement, the two women inside the car were still alive.
Some debris from the crash fell to the streets below, sending pedestrians scurrying for cover, but most fell onto the buildings setbacks at the fifth floor. Still, a bulk of the wreckage remained stuck in the side of the building. After the flames were extinguished and the remains of the victims removed, the rest of the wreckage was removed through the building.
The plane crash killed 14 people (11 office workers and the three crewmen) plus injured 26 others. 

Though the integrity of the Empire State Building was not affected,


B-25 Mitchell

Though the integrity of the Empire State Building was not affected,

Jet crashes into building from you tube

September 07, 2006

The El Al Boeing 747 crashed on 4 October 1992 shortly after take-off from Schipol

On 4 October 1992, El Al Flight 1862, a Boeing 747 cargo plane of the Israeliairline El Al, crashed into the Groeneveen and Klein-Kruitberg flats in theBijlmermeer (colloquially "Bijlmer") neighbourhood (part of Amsterdam Zuidoost) of AmsterdamNetherlands. A total of 43 people were killed, consisting of the plane's crew of three and a non-revenue passenger in a jump seat, plus 39 persons on the ground. Many more were injured


The integrity of the Empire State Building was not affected, AFTER PLANE CRASH IN 1945