Development of a Runway Veer-Off Location Distribution Risk Assessment and Reporting Template (2014)

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31 Analysis Software Overview Analysis software for aircraft veer-offs developed in this study is named Lateral Runway Safety Area Risk Analysis (LRSARA). It integrates the approach and the models devel- oped into an analysis tool that is user-friendly and incorpo- rates three basic interfaces: (1) an interface for entering data, characterizing the RSA, and managing files; (2) a module that contains the algorithm to check the validity of data, process the information, and perform the calculations to estimate veer-off risk; and (3) an interface to organize results and out- put in report format. The software program and the accompanying user guide (presented in Appendix G) are available for download at the Transportation Research Board (TRB) website. The user guide may also be accessed from the Help menu within the program. The software main screen is shown in Figure 29. Software Capabilities With LRSARA, airport stakeholders may analyze non- standard RSA widths and the presence of obstacles in the vicinity of the runway lateral RSA. A summary of LRSARA capabilities is presented below: • Perform full-risk assessment for multiple runways. • Enter multiple obstacles in each RSA scenario. • Characterize two different categories of obstacles (ground or high). • Define and analyze non-standard (non-rectangular) RSA geometry. • Internally integrate operations and weather data from separate files. • Automatically convert operations and weather data into parameters used by probability models. • Include database of aircraft with capability to add new or edit existing aircraft characteristics. • Automatically compute runway criticality factor for each operation. • Automatically correct for required distances (landing and takeoff) based on elevation, temperature, wind, and runway surface condition. • Generate analysis reports from software with summaries of the following parameters: – Average risk for each type of incident by runway, by RSA section, and total for the airport. – The expected number of years for an accident to occur for a user-defined annual traffic volume and growth rate. – Percentage of operations subject to a probability higher than a user-defined target level of safety (TLS). – Graphical outputs with the distribution of risk for each RSA and each type of event. • Run a simplified analysis using default or user-defined veer- off probabilities, with no need to enter historical operations and historical weather conditions. Input Data Input data required to run the analysis include the follow- ing information: • Sample of historical operations data (date and time, air- craft model, runway used, type of operation, etc.) if full analysis is selected. • Sample of weather data for the airport covering the histori- cal operations sample period (wind, temperature, precipi- tation, visibility, etc.). • Characteristics of runways (elevation, direction, declared distances, displaced threshold) if full analysis is selected. • Characteristics of RSAs (geometry and location, size, and category of obstacles). • General information (airport annual traffic volume, annual growth rate). Much of the input information is arranged in table for- mat. Operations and weather data are entered using Micro- soft Excel templates with automatic checks for value ranges C H A P T E R 6

32 and data format. Figure 30 shows the program screen and template to input operations data. The template for drawing the lateral RSA area was also cre- ated using Microsoft Excel. It consists of a canvas area formed by a matrix of cells. Each cell corresponds to a coordinate that is referenced to the runway edge. To include an obstacle, the user assigns a letter to each cell to define the type of obstacle. Enter- ing “g” represents a ground obstacle (e.g., ditch, rough terrain, depression). If letter “w” is entered, it represents a wing-level obstacle to account for the risk of aircraft wings or fuselage striking the obstacle in the given location. After entering a let- ter, the color of the cell will change according to the type of obstacle entered to facilitate the visualization of the drawing. Figure 31 shows an example of an RSA defined with the tool. Output and Interpretation Two analysis alternatives are available: full and simplified. In full analysis it is necessary to enter historical operations and weather conditions for the airport. The information will feed the frequency models for each historical operation at the airport. If simplified analysis is selected, the probabilities of landing and takeoff veer-offs are fixed and either default val- ues from ACRP Report 51 will be used, or the user may define the two probabilities. When the analyses are completed, the user may see the results using the Output option in the main menu. There are two types of results: runways or the consolidated results for the whole airport. Within each of these options, the user can view the results for probability of landing and takeoff veer-off events or view the analysis output for the risk of accidents. Each worksheet contains the risk estimates for one type of veer-off and individual operation and the total veer-off risk during landings and takeoffs. The results for each individual runway are provided in separate Excel output files. The sum- mary table provides the average risk for each type of accident and expected number of years for a veer-off accident to occur. The accumulated risk distribution is provided in graphical form for the lateral RSA. The results for the entire airport are provided in one Excel output file. The user must create the output files for each run- way prior to creating the output file for the airport. An example presenting the summary of results for the whole airport using the full analysis is shown in Figure 32. The main table contains a summary of average risk levels for each type of veer-off acci- dent and total risk involving both runways analyzed. Risk levels are shown in terms of accident rates per number of operations and expected number of years for one accident to occur. Addi- tional tables are presented showing the average risk for each runway, the percentage of movements with higher risk, and the number of operations challenging the lateral RSA sections associated with each runway. Similar output reports are gener- ated if the analysis involves multiple runways. The first table contains three user-defined fields: the airport annual traffic volume, the expected annual traffic growth rate, and the TLS. These values reflect the options entered during the analysis input phase and may be modified by the user directly in the output spreadsheet. When these parameters are changed, the average number of years between accidents will change to reflect the new traffic volume estimated for future years. If the TLS is modified, the percentage of movements above the TLS will change automatically to reflect the new TLS value. Figure 29. LRSARA—main program screen.

Figure 30. Example of input screen and template. Figure 31. RSA characterization using Microsoft Excel template.

34 Figure 32. Example output summary. Risk of Accident - Summary of Results Overall Results Risk Analysis Summary of Results by Runway Summary Table Probability of Event per Operation 15 33 LDVO 5.78E-07 5.54E-07 LDVO 2.0E-07 81 5.1 30 TOVO 1.21E-07 1.55E-07 TOVO 5.8E-08 >100 0.3 30 Total 1.2E-07 73 0.1 17 Risk of Accident in Events per Operation Airport Annual Volume: 50,000 15 33 Expected Traffic growth rate: 2.00% LDVO 1.95E-07 2.07E-07 Target Level of Safety (TLS): 1.0E-06 TOVO 5.37E-08 6.21E-08 Airport: Anywhere Airport Average # of Years Between Accidents Date of Analysis: 7/12/2013 Type of Accident Analyst: Jane Doe 15 33 LDVO >100 >100 TOVO >100 >100 Percent Events Above 1.0E-06 Type of Accident 15 33 LDVO 5.59 4.67 TOVO 0.18 0.38 LDOR 0 TOOR 0 Summary of Operations Challenging the RSAs LDUS 0 Movements Challenging each RSA LDVO 918 Type of Accident TOVO 1068 15 33 Total 1986 LDVO 447 471 TOVO 548 520 Total 995 991 RSA RSA Type of Accident Accident Average Risk of Accident Avrg # of Years to Accident % Ops Above TLS Avrg # of Years to Accident for TLS Accident NOD Note: fields in yellow may be changed by user Type of Accident RSA RSA RSA 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 100 200 300 400 500 600 700 800 900 Cu m ul ati ve % O ps Fr eq ue nc y of O ps Probability Interval Histogram of Total Risk Frequency Cumulative % Notes 1 - Fields in orange may be directly changed in spreadsheet by user 2 - The total risk for the airport is per movement (landing and taking off) 3 - Each takeoff and landing will challenge the lateral safety areas for veer-offs 4 - Histogram for the whole airport is for any type of event and includes each movement challenging the LRSA