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8 Literature Review Collection and Preparation of Data Accident & Incident Aircraft Normal Operations Development of Risk Development of Test Development of Models Plan Software Outline Interim Meeting Development of Execution of Test Plan Analysis Software Select airports Collect airport data Testing of Analysis Run analysis for selected airports Software Validate models & software Revised Software Final report Figure 5. Study tasks. Accident and Incident Data the runway ends and within 1000 ft of the runway centerline. The criteria represents the area where the overwhelming ma- Accident and incident data were collected from the following jority of runway excursions and undershoots occur and are sources: similar to those used in ACRP Report 3 and by the FAA (David FAA Accident/Incident Data System (AIDS). 1990). Using such criteria, 1414 accidents and incidents were FAA/National Aeronautics & Space Administration (NASA) identified to provide the information used to develop the Aviation Safety Reporting System (ASRS). frequency and location models. Events that took place since National Transportation Safety Board (NTSB) Accident 1980 and for which reports were available were included in Database & Synopses. the database. MITRE Corporation Runway Excursion Events Database Part of the data used to develop the frequency models was V.4 (2008). complemented from other sources of information, particu- Transportation Safety Board of Canada (TSB). larly for aircraft, airport, and meteorological conditions. For International Civil Aviation Organization (ICAO) Accident/ example, in some cases the weather information during the Incident Data Reporting (ADREP) system. incident was missing and the actual METAR for the airport Australian Transport Safety Bureau (ATSB). was obtained. In other situations, the runway used was miss- Bureau d'Enqutes et d'Analyses pour la Scurit de l'Avi- ing and the FAA Enhanced Traffic Management System Per- ation Civile (BEA). formance Metrics (ASPM) was consulted. UK Air Accidents Investigation Branch (AAIB). New Zealand Transport Accident Investigation Commission Filter Applied to the Data (TAIC). Air Accident Investigation Bureau of Singapore. Criteria for filtering data were established to make the events Ireland Air Accident Investigation Unit (AAIU). comparable. The first filter was an attempt to use information Spain Comisin de Investigacin de Accidentes e Incidentes from only specific regions of the world having accident rates de Aviacin Civil (CIAIAC). that are comparable to the U.S. rate. This information was com- Indonesia National Transportation Safety Committee bined with U.S. data to develop the location models. For the (NTSC). frequency models, only U.S. data were used because compre- Netherlands Aviation Safety Board (NASB). hensive incident records are only available in the United States. The criteria used are shown in Table 1. More than 260,000 aviation accident and incident reports The accident and incident database was organized in Mi- were screened from 11 countries to identify the cases relevant crosoft Access. The ACRP Report 3 database was modified to to this study. Out of those, more than 140,000 events were simplify its use. The system provides the software tools needed screened from U.S. databases. The relevant events were fil- to utilize the data in a flexible manner and includes the capa- tered prior to gathering data from each report. bility to add, modify, or delete data from the database, make A list of accidents and incidents containing the cases used for queries about the data stored in the database, and produce model development is presented in Appendix B of this report. reports summarizing selected contents. Figure 6 shows the The list includes the accidents that occurred within 2000 ft of database organization.

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9 Table 1. Filtering criteria for accidents and incidents. Filter # Description Justification 1 Remove non-fixed wing aircraft entries Study is concerned with fixed wing aircraft accidents and incidents only 2 Remove entries for airplanes with Cut off criteria to maintain comparable level of pilot certified max gross weight < 6,000 lbs qualifications and aircraft performance to increase the validity of the modeling 3 Remove entries with unwanted FAR Some FAR parts have significantly different safety parts. Kept Part 121, 125, 129, 135 and regulations (e.g., pilot qualifications). The following selected Part 91 operations. cases were removed: o Part 91F: Special Flt Ops. o Part 103: Ultralight o Part 105: Parachute Jumping o Part 133: Rotorcraft Ext. Load o Part 137: Agricultural o Part 141: Pilot Schools o Armed Forces 4 Remove occurrences for unwanted Study focus is the runway safety area. Situations phases of flight when the RSA cannot help mitigating accident and incident consequences were discarded to increase model validity. 5 Remove all single engine aircraft and Piston engine aircraft are now used less frequently all piston engine aircraft entries in civil aviation and therefore have been removed, to increase the validity of the modeling. Moreover single and piston engine aircraft behave differently in accidents due to the lower energy levels involved and the fact that the major focus of this study is air carrier aircraft. 6 Remove all accidents and incidents It would be unfeasible to have an RSA with more when the point of first impact and the than 2000ft beyond the threshold or 1000ft from the wreckage final location is beyond runway centerline, the gain in safety is not 2000ft from runway end and 1000ft significant and both the previous ACRP study and from runway centerline. the FAA study used the 2000ft criteria (David 1990). Figure 6. Accident and incident database for aircraft overruns, undershoots, and veer-offs.

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10 Accidents/Incidents by Type 500 400 # of Events 300 200 100 0 LDOR LDUS LDVOFF TOOR TOVOFF ACC 138 51 111 61 22 INC 363 60 448 62 98 Type of Event Figure 7. Summary of accidents and incidents by type. The database includes, for each individual event or opera- and incidents; veer-offs accounted for 48%; and undershoots tion, the reporting agency, the aircraft characteristics, the accounted for only 8% of the total number of events. runway and environmental conditions, event classification (ac- Figure 9 presents the number of incidents and accidents by cident or incident), and other relevant information such as year from 1978 to 2008. The number of events reported in the consequences (fatalities, injuries, and damage) and causal 1970s was relatively low, most likely due to underreporting or contributing factors required to develop the probability and lower volumes of traffic. The number of events increased models. A unique identifier was assigned to each event. slowly, and there is a sharp drop during the past 3 years. It is possible that some events are still undergoing the investiga- tion and that reports were not available by the time data col- Summary of Data lection was completed. Figure 7 presents the summary of accidents and incidents Figures 10 to 14 show the distribution of accidents and in- by type, and Figure 8 shows the relative percentages for each cidents according to their location. For overruns and under- type. Landing events accounted for 83% of the events. Over- shoots, the locations refer to the longitudinal distance from runs (landing and takeoffs) accounted for 44% of accidents the runway end. For veer-offs, it is the lateral distance from the runway longitudinal edge. Five hundred one landing overrun events were identified. Events by Type In approximately 95% of the events, the aircraft stopped within 1000 ft after overrunning the runway, and close to 77% stopped TOOR within 500 ft. TOVOFF 9% 8% One hundred eleven landing undershoot events were iden- tified, and in approximately 94% of the cases, the aircraft LDOR 35% touched the terrain within 1000 feet of the runway arrival end. Approximately 85% touched down within 600 feet and 80% within 500 feet. Veer-off distances were measured from the runway edge. Of the 559 cases of landing veer-off identified, in approxi- mately 80% of the cases the fuselage of the aircraft deviated less than 175 feet from the runway edge. For 88% of the events, the aircraft was within 250 feet of the runway edge. A total of 123 takeoff overrun accidents and incidents were LDVOFF identified. For approximately 83% of the cases, the stop loca- 40% LDUS tion was within 1000 feet of the runway departure end, and 8% for 56%, the aircraft stopped within 500 feet. Figure 8. Percentage of accidents and incidents Of the 120 takeoff veer-off accidents and incidents, in by type. approximately 76% of the cases the fuselage of the aircraft

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11 Reported Events per Year 70 ACC 60 INC Number of Occurrences 50 40 30 20 10 0 96 98 00 02 04 06 08 78 80 82 84 86 88 90 92 94 19 19 20 20 20 20 20 19 19 19 19 19 19 19 19 19 Year Figure 9. Number of reported accidents and incidents from 1978 to 2008. Location Distribution for LDOR Events Location Distribution for LDVO Events 120 70 100 60 50 80 # of Events # of Events 40 60 30 40 20 20 10 0 0 00 00 00 0 0 0 0 0 00 00 e 0 0 0 0 0 e 50 0 0 0 0 10 30 50 70 90 or 30 35 40 45 50 or 10 15 20 25 11 13 15 17 19 M M Distance from Threshold (ft) Distance from Runway Edge (ft) Figure 10. Location distribution for landing Figure 12. Location distribution for landing overruns. veer-offs. Location Distribution for LDUS Events Location Distribution for TOOR Events 35 30 30 25 25 20 # of Events # of Events 20 15 15 10 10 5 5 0 0 0 0 0 0 0 00 00 00 00 00 e 00 00 00 00 00 ss 0 0 0 0 0 10 30 50 70 90 or 90 70 50 30 10 Le 11 13 15 17 19 19 17 15 13 11 M Distance from Threshold (ft) Distance from Threshold (ft) Figure 11. Location distribution for landing Figure 13. Location distribution for takeoff undershoots. overruns.