System: National Space Transportation System (NSTS)-the space shuttle Some observers still worry that, despite NASA’s late adoption of quantitative risk assessment, its internal culture and its fear of political opposition may be pushing it to repeat dangerous errors of the shuttle program in the new space station program. Political pressures, coupled with the lack of hard numerical data, led to differences of more than three orders of magnitude in the few quantitative estimates of a shuttle launch failure that NASA was required by law to conduct. Congress and had all the money it needed, the shuttle program was strongly criticized and underbudgeted from the beginning. Whereas the Apollo program was widely supported by the President and the U.S. This Catch 22–the agency lacks appropriate statistical data because it did not believe in the technique requiring the data, so it did not gather the relevant data–is one example of how an organization’s underlying culture and explicit policy can affect the overall reliability of the projects it undertakes.Įxternal forces such as politics further shape an organization’s response. But success is slow because of past official policy that favored “engineering judgment” over “probability numbers,” resulting in NASA’s failure to collect the type of statistical test and flight data useful for quantitative risk assessment. The program’s goals are to establish a policy on risk management and to conduct risk assessments independent of normal engineering analyses. 28, 1986, Challenger accident that killed seven astronauts. NASA started experimenting with this program in response to the Jan. He maintains that probabilistic risk analysis can go beyond design-oriented qualitative techniques in looking at the interactions of subsystems, ascertaining the effects of human activity and environmental conditions, and detecting common-cause failures. “The real value of probabilistic risk analysis is in understanding the system and its vulnerabilities,” said Benjamin Buchbinder, manager of NASA’s two-year-old risk management program. Navy, Washington, D.C., he still holds that risk is minimized not by statistical test programs, but by “attention taken in design, where it belongs.” His design-oriented view prevailed in NASA in the 1970s, when the space shuttle was designed and built by many of the engineers who had worked on the Apollo program. “They have no place in engineering anywhere.” Now director of reliability management and quality assurance for the U.S. “Statistics don’t count for anything,” declared Will Willoughby, the National Aeronautics and Space Administration’s former head of reliability and safety during the Apollo moon landing program. The article has been widely cited in both histories of the space program and in analyses of engineering risk management. To mark the anniversary, IEEE Spectrum is republishing this seminal article which first appeared in June 1989 as part of a special report on risk. Editor’s Note: Today is the 30 th anniversary of the loss of the space shuttle Challenger, which was destroyed 73 seconds in its flight, killing all onboard.
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