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.

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

R.G.W. Cherry & Associates Limited

The Federal Aviation Administration (FAA), Transport Canada, and the United Kingdom Civil Aviation Authority requested a Risk and Benefit Cost Model be developed 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 explains the data used by the Model, its algorithms, and the way in which the Model may be used.

The Model addresses the potential fire threat from all forms of cargo, including the bulk shipment of lithium batteries (primary and secondary) because they likely contributed to two of the five freighter fire accidents that have occurred on U.S.-registered airplanes. The Model displays the number of accidents through 2020 and costs, benefits, and the benefit/cost ratios through to 2025.

The Model prediction of the average number of accidents likely to occur from 2011 to 2020, if no mitigation action is taken, is approximately 6—with a 95-percentile range of approximately 2 to 13. If no mitigation action is taken, accident costs are likely to average approximately $44 million (U.S.) per annum over the period 2011 to 2025. 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 2010 through 2025 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)

R.G.W. Cherry & Associates Limited

The National Transportation Safety Board has recommended that fire suppression systems be installed in the cargo compartments of all cargo airplanes operating under 14 CFR Part 121. Currently, Class E cargo compartments, which are the primary cargo compartment type used in US cargo airplanes, do not require fire suppression systems. In response to this recommendation, FAA has requested that a cost/benefit analysis be carried out relating to the installation of on-board fire detection and extinguishment systems in cargo airplanes. This report contains the results of this analysis and a description of the methodology used.

The analysis assessed whether fire suppression systems, fitted to the cargo bays of cargo airplanes, type certificated to FAR Part 25 and operating under FAR Part 121, are likely to be cost beneficial. Potential benefits will result from a reduction in Injuries (Fatal and Serious) to personnel, a reduction in the damage incurred to the aircraft and its cargo, and a reduction in the damage that might be incurred to property on the ground. Potential costs are those that might be incurred from the installation and operation of fire suppression systems.

A mathematical model has been developed to assess the benefit. The model utilizes statistical distributions derived from data on in-service airplanes and accident information. Cost assessments were made for modifying cargo aircraft to the new Type F Cargo Compartment being considered for combi aircraft. These cost assessments were based on the installation of a Halon type fire suppression system together with suitable cargo compartment liners. The data used in the cost assessment was based on that contained in the ARAC document relating to main deck class B cargo compartments.

The results of the study suggest that crew injuries (Fatal and Serious combined) and the loss of the aircraft and cargo in freighter fire accidents are likely to be a significant factor in the prediction of benefit. Collateral ground damage does not appear to contribute significantly to the prediction of benefit. It is concluded that Halon fire suppression systems, or alternatives that are likely to be developed for below floor cargo compartments, are unlikely to be cost beneficial for the cargo compartments of cargo aircraft. Fire suppression systems, of the kind currently being considered for the cargo compartments of combi aircraft, may prove to be cost beneficial, particularly on larger cargo aircraft.

RGW Cherry and Associates

The objective of this analysis was to assess the number of Serious Injuries and Fatalities that might be avoided from the use of ’16g dynamic seats configured without enhancements to head injury criteria’ and to compare this with the assessed benefit from ’fully compliant dynamic seats’.

R G W Cherry & Associates Limited

A benefit analysis has been carried out to derive the life saving potential of a Cabin Water Spray system in conjunction with enhanced Fuselage Burnthrough Protection from large external pool fires. The effects of fire and evacuation related requirements that were introduced after the accident date have also been taken into account.

All benefits derived are based on the number of lives saved for the world fleet of western-built aircraft type certificated for more than 30 seats and are relative to the period 1967 to 1996.

Two configurations of Cabin Water Spray system have been considered in the benefit analysis - a Modular and a Singular system. It is assumed that a Modular system would consist of three separate water supplies located in the front, mid and rear sections of the fuselage and would be activated only in the areas affected by fire. A Singular system would have only one source of supply located in the centre section of the fuselage. It would provide benefit in this area should the nose and/or tail sections became detached in the accident.

Benefit has been determined for aircraft configurations having either enhanced Fuselage Burnthrough Protection or a Cabin Water Spray System. In addition, the study reassesses the benefit from Cabin Water Sprays on aircraft already configured with enhanced Fuselage Burnthrough Protection.

The analysis has been accomplished by analysing past accidents to western-built aircraft over the period 1967 to 1996. Two methodologies were used to determine the total assessed benefit for all accidents studied. The first was based on an assessment of the number of lives saved in each accident from which a determination was made of the average number of lives saved per year and its likely range. The second method was to determine the rate of occurrence per year of the number of accidents from which the improvements considered might yield benefit.

The merits of each method are discussed and it was considered that the best prediction of benefit is that derived from Method 2.

Enhanced Fuselage Burnthrough Protection has been reassessed and the life saving benefit increased from that previously estimated. The number of lives saved per year is estimated to be approximately 12.

The assessment for a Singular Cabin Water Spray system on aircraft that are configured without enhanced Fuselage Burnthrough Protection is approximately 27 lives per year.

The number of lives saved per year, by a Modular Cabin Water Spray system, on aircraft that are configured without enhanced Fuselage Burnthrough Protection is assessed to be approximately 34 lives per year.

The assessment for Singular Cabin Water Spray systems and enhanced Fuselage Burnthrough Protection combined is approximately 34 lives per year.

The number of lives saved per year by Modular Cabin Water Spray systems and enhanced Fuselage Burnthrough Protection combined is assessed to be approximately 46 lives per year.

For aircraft that are configured with enhanced Fuselage Burnthrough Protection, Cabin Water Spray systems would save a further 22 lives per year for a Singular system, and 34 lives per year for a Modular system.