Typical cases of software failure

Case 1:ariane 5 Rockets

June 4, 1996, the Ariane 5 rocket was first launched in the French Guiana Space Center. 37 seconds after the launch of the rocket off its flight path and a sudden explosion, and the Ariane5 rocket into Ashes with 4 solar wind observation satellite. This is a major tragedy in the history of the world's spaceflight, and it is also the most costly software failure event in history.

Subsequent investigations revealed that the computer controlling the inertial navigation system sent an invalid data to the computer controlling the engine nozzle because of an overflow when converting a 64-bit floating-point number into a 16-bit signed integer. This overflow value measures the rocket's horizontal rate, and when the developer designs the software for the Ariane 4 rocket, it carefully analyzes the rocket's level rate and determines that its value will never exceed a 16-digit number. The Ariane 5 rocket is nearly 5 times times faster than the Ariane 4, apparently exceeding a 16-digit range. Unfortunately, developers are simply reusing this part of the program when designing the Ariane 5 rocket, without checking the assumptions on which it is based.

Case 2:therac 25 Radiation therapy instrument

The Therac series of instruments is a medical high-energy electron linear Accelerator made by Canadian Atomic Energy Co., Ltd. (AECL) and the French CGL company, used to kill diseased tissue cells while minimizing its impact on surrounding healthy tissues, and Therac 25 belongs to the third generation of high-energy electron linear accelerators for medical use. In the mid 1980s, Therac 25 had several medical incidents in the United States and Canada, 5 patients died after treatment, while the remaining patients were severely burned by ultra-dose radiation.

The accident of the Therac 25 radiotherapy instrument is caused by operator errors and software defects. When an operator enters an error and corrects it immediately, the system displays an error message and the operator has to restart the machine. At the start of the machine, the computer software did not cut off the X-ray beam, the patient has been on the treatment stage to receive an excessive X-rays, the final radiation dose reached the saturation of 25000, and to the human body, the radiation dose of 1000 rad is already fatal.

Case 3: Tokyo Stock Exchange

November 1, 2005, Japan's Tokyo Stock Exchange stock trading system in a large-scale system failure, resulting in all the stock Exchange total stop, just 2 hours caused the loss of hundreds of billions of dollars. The failure was due to a defect in the trading process that was updated in October in order to enhance the system's processing power, which affected the use of the trading system because of incompatible files.

Case 4:12,306 train ticket online booking system

China's 12306 Railway train ticket online booking system lasted two years to develop successfully, costing 300 million yuan, put into operation on June 12, 2011. January 8, 2012 Spring Festival launch, 9th site clicks more than 1.4 billion times, the system appears the website crashes, log in slowly, cannot pay, deduct money not to issue the ticket and so on serious problem. September 20, 2012, due to the Mid-Autumn Festival and "11" Golden Week, the site hits 1.49 billion times a day, the sale of tickets more than the peak of the Spring Festival, the network congestion, repeated queuing and other phenomena. The root cause of the failure lies in the system architecture planning and the defect of ticket issuing mechanism, which cannot support such a large amount of concurrent transactions.

Typical cases of software failure