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|Title:||A Study Analyzing the Trends in Accidents and Fatalities in Large Transport Airplanes|
|Author:||R.G.W. Cherry & Associates Limited|
This study was commissioned by the Federal Aviation Administration to analyze accident data to large transport airplanes registered in the United States of America and worldwide. It assessed trends in airplane safety in terms of number of accidents, accident rates, number of fatalities, fatality rates, the probability of an accident being survivable, and the probability of death in a survivable accident.
Over the study period, there has been a marked reduction in the total accident rate, both for the world fleet and the U.S. fleet. This reduction is apparent when the accident rate is measured on a per-flight, per-passenger, or per-revenue-passenger-mile basis.
The survivability of accidents has also shown a marked improvement over the study period with a greater proportion of accidents being survivable and the proportion of occupants surviving an accident increasing. These improvements are apparent in both the world fleet and the U.S. fleet.
It would seem that fatalities attributable to impact represent a larger proportion of the total number of fatalities in survivable accidents than those that are caused by fire. However, the extent to which the number of fatalities attributable to each of these two areas might be reduced is beyond the scope of this study.
|Title:||A PROBABILISTIC ANALYSIS OF PASS/FAIL FIRE TESTS|
|Author:||Richard E. Lyon and Natallia Safronava|
Several material fire properties were evaluated as sole explanatory variables for two pass/fail flammability tests using two different probabilistic models. The fire behavior and properties investigated span the range of commercial polymers and flame-retardant plastics. The flammability tests included a fire test used by the Federal Aviation Administration for regulatory purposes and a flame test used by Underwriters Laboratories, Inc., both with categorical outcomes. The probabilistic analysis involved nonlinear least squares regression of the fire test data coded as a binary (pass/fail) outcome on each of the continuous explanatory variables using the logistic response function and a new (phlogistic) response function. The chi-square test showed that both probability models were appropriate for describing the likelihood of passing fire and flame tests using the heat release capacity, heat of combustion, volatile fuel fraction, and heat release parameter as the sole explanatory variable, but neither model was appropriate for thermal decomposition temperature as an explanatory variable. The overall efficacy of the thermal and combustion properties for predicting flammability test results based on the correlation coefficient and mean deviation of the grouped data from the fitted functions is: heat release capacity ˜ heat of combustion > heat release parameter > volatile fuel fraction > thermal decomposition temperature. Both probabilistic models are suitable for determining the likelihood of passing a flammability test using the thermal and combustion properties investigated, but the phlogistic model provides a better fit of the data when the likelihood of passing the test approaches unity.
|Title:||Freighter Airplane Cargo Fire Risk, Benefit and Cost Model (Model Version 5)|
|Author:||R.G.W. Cherry & Associates Limited|
The FAA, Transport Canada, and the UK CAA jointly developed a Risk and Benefit Cost Model to assess the likely number of U.S.-registered freighter fire accidents, and the Benefit Cost Ratio associated with seven mitigation strategies identified by the FAA. This report is structured to explain the data used by the Model Version 5, its algorithms, and the way in which the model may be used.
Model Version 5 is a development of earlier models. Extra functionality has been added and data are now appropriate to the U.S.-registered freighter fleet in 2011.
The model addresses the potential fire threat from all forms of cargo, including that from the bulk shipment of lithium batteries (primary and secondary) since it is considered they are likely to have had a contribution to two of the five freighter fire accidents that have occurred on U.S.-registered airplanes. The model displays the number of accidents through to 2021, and costs, benefits and the benefit cost ratios through to 2026.
The model predicts that the average number of total accidents likely to occur during the next 10 years, 2012 to 2021, if no mitigation action is taken, is approximately 6, ranging from 2 to 12, at 95% percent confidence interval. If no mitigation action is taken, accident costs are likely to average approximately $50 million (U.S.) per annum over the period 2012 to 2026. The primary contribution to freighter fire accident costs is the value of the airplane - with values of approximately 90% of the total accident cost for the larger freighter airplanes. However, the model predictions of accident costs are based on the assumption that the composition of the U.S.-registered freighter fleet will be largely unchanged from 2011 through 2026 in terms of the size and value of airplanes.
The costs of implementing the proposed mitigation strategies are currently not known to a sufficient level of accuracy to make accurate determinations of benefit cost ratios. However, the model has been constructed to allow user inputs of costs once they become available.