Update of aircraft crash rates used by HSE in assessing hazards from chemical, process and other major hazard installations Prepared by the Health and Safety Executive RR1140 Research Report © Crown copyright 2019 Prepared 2017 First published 2019 You may reuse this information (not including logos) free of charge in any format or medium, under the terms of the Open Government Licence. To view the licence visit ww w.nationalarchives.gov.uk/doc/open-government-licence/, write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email [email protected]. Some images and illustrations may not be owned by the Crown so can not be reproduced without permission of the copyright owner. Enquiries should be sent to [email protected]. The Health and Safety Executive (HSE) provides advice on land use planning in the vicinity of major accident hazard sites and major accident hazard pipelines. As part of this process, HSE publish a guidance document, Failure Rate and Event Data, which contains failure rates for pieces of equipment found in major hazard chemical and process sites. The guidance document also contains information on event data such as aircraft crash and flooding, which are used when assessing the risks from such major hazard sites. An event such as an aircraft crash could lead to a release of a hazardous substance that could potentially harm people. Th e aircraft crash rates were previously updated in 2009 using data up to 2006. This report updates the crash rates u sing data from 1990 to 2013. The methodology used to calculate the crash rates is also detailed. Uncertainty levels p rovide upper and lower bounds to the calculated crash rates to account for the uncertainty in the data that is used to derive the crash rates. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. 2 UpdateLorem of ipsu aircraftm dcroashlor ratessit a usedmet by HSE in assessingconsectetuer hazards fromadipiscing chemical elit, process and other major hazard installations Zoe Chaplin Hea lth and Safety Executive Harpur Hill Buxton Derbyshire SK17 9JN 3 Acknowledgements The author gratefully acknowledges the assistance received from Graham French of the Civil Aviation Authority (CAA), who provided data used in this report. 4 KEY MESSAGES The Health and Safety Executive (HSE) provides advice on land use planning in the vicinity of major accident hazard sites and major accident hazard pipelines. As part of this process, potential external events are considered that could damage the site or pipeline. One of these events is aircraft crashes. If an aircraft crash occurs, the equipment on the site can be damaged leading to a release of the hazardous substance and potentially harming people. Information on aircraft crash rates was previously updated in 2009 to use data up to 2006. HSE have updated the aircraft crash rates currently used to incorporate data up to 2013. The methodology used to calculate the crash rates had been reviewed and modified previously. Both the current and revised methodologies have been detailed and the revised methodology was used to update the crash rates. 5 EXECUTIVE SUMMARY HSE provides advice on Land Use Planning (LUP) in the vicinity of major accident hazard sites and major accident hazard pipelines. As part of this process, HSE publish a guide to failure rates for vessels and pipework for use in LUP cases (hereafter referred to as Failure Rate and Event Data1). As part of this guide, external hazards are identified that may also need to be taken into consideration when assessing the hazards from chemical and process sites. One of these events is aircraft crashes. The aircraft crash rates and methodology reported in Failure Rate and Event Data were last updated in 2009 using data up to 2006. This report is aimed at risk assessment modelling specialists for major accident hazard sites. The available methodologies on calculating aircraft crash rates were reviewed in 2015 and some of the crash rates were recalculated using data from 1990 to 2013. It was decided that Failure Rate and Event Data should be modified to incorporate the more recent information. In addition, further information has been obtained to update the crash rates that were not considered as part of the recent review. The crash rates are separated into two categories: background and airfield related. The background rates apply at distances greater than 5 miles from any airfield and relate to the cruising stages of flight. The airfield related crash rates apply within 5 miles of the airfield and are associated with the take-off and landing stages of flight. The background crash rates and airfield related crash rates have been updated for five categories of aircraft. A 95% confidence interval has been included as part of the calculations to provide an indication of the level of uncertainty surrounding the data. The revised background crash rates are given in Table 1. Table 2 reports the revised airfield related crash rates. Table 1 Calculated background crash rates (× 10-6 km-2 yr-1) for the period 1990 to 2013 for Great Britain. Aircraft type Mean Lower confidence limit Upper confidence limit Light aircraft 18.5 15.1 22.4 Small transport aircraft 2.2 1.1 3.8 Large transport aircraft 0.7 0.2 1.9 Helicopters 10.3 7.8 13.4 Military combat aircraft 6.7 4.7 9.2 Total 38.4 28.9 50.7 1 HSE (2012). Failure rate and event data for use within risk assessments (28/06/2012). http://www.hse.gov.uk/landuseplanning/failure-rates.pdf 6 Table 2 Airfield related crash rates (× 10-6 per movement) for the period 1990 to 2013 for Great Britain Aircraft type Mean Lower confidence limit Upper confidence limit Light aircraft 2.5 2.1 2.9 Small transport aircraft 3.8 2.5 5.5 Large transport aircraft 0.08 0.02 0.24 Civil helicopters 2.4 1.6 3.5 Military combat aircraft 3.5 2.5 4.8 7 CONTENTS KEY MESSAGES……………………………………………………………………. 5 EXECUTIVE SUMMARY ……………………………………………………………. 6 1 INTRODUCTION ............................................................................................. 9 2 METHODOLOGY .......................................................................................... 10 2.1 Current Methodology ..................................................................................... 10 2.2 Revised Methodology .................................................................................... 11 3 REVISED CRASH RATES ............................................................................ 12 3.1 Background crash rate ................................................................................... 12 3.2 Airfield related crash rate ............................................................................... 12 3.2.1 Small and Large Transport Aircraft .................................................................................. 13 3.2.2 Light Aircraft .................................................................................................................... 13 3.2.3 Helicopters ....................................................................................................................... 18 3.2.4 Military Combat Aircraft .................................................................................................. 20 3.2.5 Summary of crash rates ................................................................................................... 20 4 CONCLUSIONS ............................................................................................ 21 5 APPENDIX A: BACKGROUND RATE DATA ............................................... 22 6 APPENDIX B: AIRFIELD RELATED RATE DATA ....................................... 33 7 REFERENCES .............................................................................................. 47 8 1 INTRODUCTION The Health and Safety Executive (HSE) publish a guide to failure rates for vessels and pipework for use in Land Use Planning (LUP) cases [1] (hereafter referred to as Failure Rate and Event Data). As part of this guide, external hazards are identified that may need to be taken into consideration when assessing the hazards from chemical, process and nuclear sites. The external hazards include lightning, flooding and aircraft crash. Aircraft have the potential to crash onto a site, causing significant damage. As part of an LUP assessment, it is therefore necessary to consider the aircraft crash rate. The aircraft crash rates and methodology reported in Failure Rate and Event Data were last updated in 2009 using data up to 2006. The crash rates are separated into two categories: background and airfield related. In both cases, crash rates are calculated for different types of aircraft (e.g. large transport, small transport, helicopters etc.). The background crash rates apply outside of a 5 mile radius of any airfield and relate to the cruising stage of flight. The airfield related crash rates apply within 5 miles of the airfield and are associated with the take-off and landing phases of flight. In 2015, HSE reviewed the available methodologies on calculating aircraft crash rates as part of another project [2]. The background crash rates were also recalculated using data from 1990 to 2013, together with the airfield related crash rates for large transport aircraft. HSE therefore decided that Failure Rate and Event Data should be modified to incorporate the more recent information.