How safe must a potential crewed launcher be demonstrated to be before it is crewed?

Fragola, J.R.

doi:10.1016/j.jlp.2009.05.009

Cited by 8 publications

(6 citation statements)

References 13 publications

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“…If all Centaur flights could be considered samples of the same distribution, then that interval would be representative of the actual vehicle reliability. But this is contrary to basic engineering judgment and previous results [12] [13], by which the latest versions of the vehicle are much less risky than the original flight, as testified to by 5 failures in the first 10 flights versus a series of 54 successes between 1993 and 1999. When using historical surrogates, a common approach is to produce an alternate ratio by discounting the historical failures using an arbitrary relevance factor [14].…”

Section: Centaur Reliability Growth At Family Levelcontrasting

confidence: 61%

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Reliability growth and the caveats of averaging: A Centaur case study

Morse¹,

Putney²,

Fragola³

2011

2011 Proceedings - Annual Reliability and Maintainability Symposium

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Section: Centaur Reliability Growth At Family Levelcontrasting

confidence: 61%

“…For all practical purposes, this makes the 4.1% -10.7% confidence interval particularly meaningless. Note that those same caveats apply to the confidence intervals for single launch vehicle families in Figure 1, as reliability growth existed within each family [13].…”

Section: Analysis Of Centaur Failures In Terms Of Defectsmentioning

confidence: 91%

Reliability growth and the caveats of averaging: A Centaur case study

Morse¹,

Putney²,

Fragola³

2011

2011 Proceedings - Annual Reliability and Maintainability Symposium

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“…The FEDS: Then, by substituting equation (14) in equation (6), the FEDS has a CDF 65,66 shown in equation (15)…”

Section: The Environmental Profile Discussion For Correlated Reliabilitymentioning

confidence: 99%

“…Such corrections should result in reliability asymptotically approaching steady state or the design reliability value. Reliability growth approach is not yet practical for landers due to limited history, but Fragola’s 14 approach for LVs can be applied in the future.…”

Section: Estimating Reliability Of Landersmentioning

confidence: 99%

Correlated reliability and an application: Propulsive landing on Mars

Sarper

2019

Proceedings of the Institution of Mechanical Engineers, Part O:

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This article discusses reliability of landers and provides a review and examples of correlated reliability. Examples are cited to show generally beneficial effects of correlation in system reliability. Then, reliabilities of two near future landing systems are studied using two analytical (Downton, and Marshall & Olkin) bivariate exponential distributions and two simulation methods that incorporate correlation in reliability calculations. Both landing systems are composed of correlated two-unit subsystems. Numerical examples show mean system life, standard deviation of the system life, mean system life confidence interval, and reliability for each lander’s propulsive descent. Both simulation method results are in between the results obtained from the two analytical methods and Downton’s method yields the most conservative reliability. This article also shows how the Downton method–based reliability value can be predicted as a function of the reliabilities obtained from the other three methods. An up-to-date literature review of all related topics is also provided.

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“…We have already recently used the methods and ideas discussed here and in our book [5] to risk, failure rate and reliability prediction for many important cases. These include human errors and recovery actions in nuclear power plants [26]; predicting rocket launch failures and space crew safety for new systems [27]; the time it takes for restoration of power following grid failure (or "blackout") [28]; predicting the rate of failure of heat exchanger tubing in new designs [29]; and the quantitative tracking of learning trends ("safety culture") in management and operation of large offshore oil and gas facilities [30]; and about 30 other key examples. While each case has its own fascinating and unique experience and data, all examples and cases can be reduced to the common learning basis, and all follow the universal laws and rules for the outcomes due to us, as humans, functioning in modern society and technological systems, whether we know it or not.…”

Section: Figure 5 the Prediction For Rare Aircraft Crashesmentioning

confidence: 99%

The Quantification of Systemic Risk and Stability: New Methods and Measures

Duffey¹

2011

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We address the question of the prediction of large failures, busts, or system collapse, and the necessary concepts related to risk quantification, minimization and management. Answering this question requires a new approach since predictions using standard financial techniques and statistical distributions fail to predict or anticipate crises. The key points are that financial markets, systems, trading and manoeuvres are not just about money, debt, stocks, instruments and assets but reflect the actions and motivations of humans, which includes the presence or absence of learning effects. Therefore we have the possibility of failures or rare or low frequency events due to human involvement. The rare or unknown event is directly due to human influence, and reflects both learning and risk taking, with the presence of the finite and persistent human error contribution while taking or exposed to risk. This presence of humans in the marketplace explains the failure of present purely statistical methods to correctly estimate, predict or determine the onset of financial crises, busts and collapses. In this essay, we unify the concepts for predicting financial systemic risk with the general theory for outcomes, trends and measures already derived for other technical and social systems with human involvement. We replace words and qualitative reasoning with measures and quantitative predictions. The paper is therefore written with an introductory section devoted to the measures relevant to risk prediction in other modern technological systems; and is then extended and applied specifically to risk prediction for financial and business systems. The resulting measures also provide useful guidance for risk governance.

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How safe must a potential crewed launcher be demonstrated to be before it is crewed?

Cited by 8 publications

References 13 publications

Reliability growth and the caveats of averaging: A Centaur case study

Reliability growth and the caveats of averaging: A Centaur case study

Correlated reliability and an application: Propulsive landing on Mars

The Quantification of Systemic Risk and Stability: New Methods and Measures

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