Failure – lessons from disaster


Case study 1: The Comet


T


he Comet was the first passenger jet. It was a beautiful piece of mechanical engineering. Passengers and


aerospace professionals loved the plane. But several fatal crashes damaged its reputation. What caused the crashes?


A company called de Havilland designed and built the jet airliner in the UK in the late 1940s. The plane cost £250,000 to design and build. The first flight was on 27th


July, 1949,


and the Comet began commercial operations in 1952 with a flight from London to South Africa.


200 400 600 800 1000 1200


0


0 5000 10000 15000 20000 25000 30000 Altitude (meters)


Figure 1: Atmospheric pressure and altitude


The airliner flew at 10,000 m. At this altitude, the pressure of the atmosphere is 75% less than at sea level. Low pressure can lead to health problems and death, so the fuselage of the plane was pressurized every flight.


On 3rd people died. Two months later, on 2nd


March, 1953, a Comet crashed in Pakistan. Eleven May, another Comet


crashed in India. All 43 people on board were killed. Airline companies stopped using the planes. Scientists examined thousands of plane fragments. After many months, they found the cause of the accidents. It was metal fatigue. Some of the metal around the windows became soft and it developed cracks. They got bigger each flight, and finally the plane fuselage blew apart.


The Comet had four jet engines in the wings. The jetliner was 50% faster than competitor planes at the time. It had a top speed of 800 kph against 500 kph. For example, it could fly from London to Tokyo in 36 hours. Other commercial flights took 85 hours. In the first year of service, Comets carried 30,000 passengers. The jets had large square windows so passengers had wonderful views of cities, mountains and deserts. Other airliners had round windows.


Grammar for reading: Understanding pronouns and noun references


The Comet was the first passenger jet plane. It was a beautiful piece of mechanical engineering. Passengers and aerospace professionals loved the plane.


Pronouns (e.g., he, her, them, etc.) refer back to a previous noun. Sometimes a new noun is another way of referring to a previous noun. Check the reference of every noun and every pronoun. Read the case study again. How is the Comet referred to? Find all the ways.


117


Pressure (millibars)


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