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.

Click here to download the model (MS Excel 2007 or later, 140 MB)

The principles and practice of pyrolysis combustion flow calorimetry as embodied in the Federal Aviation Administration microscale combustion calorimeter (MCC) are reviewed to produce a technical basis for a standard set of operating parameters and procedures that produce accurate, repeatable, and reproducible thermal combustion properties of materials as codified in the American Society for Testing and Materials (ASTM) D7309 Standard Test Method for Determining Flammability Characteristics of Plastics and Other Solid Materials Using Microscale Combustion Calorimetry. The relationship between MCC thermal combustion properties of materials and the results of fire and flammability tests are presented and discussed.

A quantitative understanding of the processes that take place inside a burning material is critical for predicting the ignition and growth of fires. To improve this understanding and enable predictive modeling, a numerical pyrolysis solver called ThermaKin was developed. This solver computes the transient rate of gaseous fuel production from fundamental physical and chemical properties of constituents of a pyrolyzing solid. It was successfully applied to the combustion simulation of a broad range of materials. One limitation of ThermaKin was that it could handle only one-dimensional burning problems. As a consequence, flame spread, which is an important contributor to fire growth, could not be simulated. This technical note presents a new computational tool, ThermaKin2D, that expands the ThermaKin model to two dimensions and combines it with a flexible analytical representation of a surface flame. It is expected that this tool will enable highly accurate simulations of flame-spread dynamics. This technical note contains a description of this new computation tool, reports results of a series of verification exercises, and demonstrates some of the ThermaKin2D capabilities.