ANNEX C Maximum Aircraft Movement Data and the Calculation of Risk and PSZs: Cork Airport
CONTENTS C1 INTRODUCTION C1 C2 SUMMARY OF INPUT DATA C2 C3 AIRCRAFT CRASH RATE C5 C3.1 AIRCRAFT CLASSIFICATION C5 C3.2 ALL CLASSES MOVEMENT WEIGHTED AVERAGE CRASH RATE C5 C3.2.1 Crash Rate (Crashes per Year) C5 C3.2.2 Average Crash Rate (Crashes per Movement) C5 C3.2.3 Weighted Average Destroyed Area C6 C3.2.4 Type of Crash C7 C3.3 ANNUAL CRASH RATE FOR EACH CRASH MODE C8 C3.4 LONGITUDINAL AND LATERAL DISTANCE CALCULATION C10 C4 IMPACT PROBABILITY CALCULATION C12 C4.1.1 Take-off Overrun - Wreckage Location C12 C4.1.2 Landing Overruns - Wreckage Location C12 C4.1.3 Take-off Crash (non overrun) C12 C4.1.4 Landing Crash (non overrun) C12 C4.1.5 Light C12 C5 INDIVIDUAL RISK CALCULATION C14 C6 CALCULATION OF THE PUBLIC SAFETY ZONE TRIANGLES C15
C1 INTRODUCTION The calculation method is based on a model produced for the UK Department of the Environment, Transport and the Regions (DETR) (1) and subsequently reported by the National Air Traffic Services (NATS) (2). The calculation method is described in Annex A. The following sections provide details of sample calculations for runways at Cork Airport. The principal input to the model is summarised in Section C2. (1) Evans, A. W., Foot, P. B. et al. Third Party Risk Near Airports and Public Safety Zone Policy. June 1997. National Air Traffic Services Limited. R&D Report 9636. RDD File Reference 8CS/091/03/10. (2) Cowell, P. G., Foot, P. B. et al. A Methodology for Calculating Individual Risk Due to Aircraft Accidents Near Airports. January 2000. National Air Traffic Services Limited. R&D Report 0007. R&DG File Reference 8RD/07/002/11. C1
C2 SUMMARY OF INPUT DATA The numbers of annual for Cork airport have been provided, according to aircraft type, for the 2000 (1), as summarised in Table C2.1 and Table C2.2. Table C2.1 Crash Frequency Summary, Year 2000 Movements: Cork Airport Boeing Class Number of per Crash rate (crashes per million ) Crash rate (crashes per ) Average MTWA (tonne) Destroyed area (hectare) NATS MODEL Class I jets 0 1.113 0-0.000 Class II-IV jets (PAX) 13,435 0.148 1.99 E-3 101 0.498 Class II-IV jets (NP) 1,429 0.444 6.34 E-4 87 0.464 Eastern jets 8 0.874 6.99 E-6 42 0.328 Executive jets 1,379 2.23 3.08 E-3 15 0.201 Turboprops T1 (PAX) 6,919 0.288 1.99 E-3 15 0.201 Turboprops T1 (NP) 155 0.864 1.34 E-4 15 0.201 Turboprops T2 494 0.782 3.86 E-4 31 0.284 Miscellaneous 804 3.27 2.63 E-3 4 0.108 TOTAL 24,623 1.08E-2 AVERAGE 0.441 33 0.2514 AEA LIGHT AIRCRAFT MODEL Piston engine 22,946 3.27 7.50 E-2 2 0.0775 GRAND TOTAL 47,569 8.59 E-2 Notes 1. Total per for the 2000. 2. MTWA - maximum take-off weight authorised. 3. PAX - passenger aircraft. 4. NP - non passenger aircraft (e.g. freight). Table C2.2 Summary of Movements, Year 2000: Cork Airport 7 25 Total 17 35 Total Grand total NATS model Landings 31 408 439 6,505 5,492 11,997 12,436 4% 51% 55% 27% 23% 50% Take offs 53 303 356 7,590 4,447 12,037 12,393 7% 38% 45% 32% 19% 50% 24,829 AEA light aircraft model Landings + Take offs 1,112 5,027 6,139 7,773 9,034 16,807 22,946 18% 82% 100% 46% 54% 100% Grand total 1,196 5,738 6,934 21,868 18,973 40,841 47,775 (1) E-mail: Alan Levey (Aer Rianta) to Daniel Quinn (ERM). 28-May-2001. C2
It is understood that the maximum perceived number of accommodated on runways 17/35 and 7/25 are estimated as 109,500 (based on 300 per day, 365 days per ) and 43,800 (based on 40% of 109,500) per. It is judged that the proportions of aircraft classes using the Airport will be similar to those corresponding to the for 2000. Therefore, the average crash rate per movement and average destroyed area remain unchanged and are the same as those detailed in Table C2.1. Table C2.3 Crash Frequency Summary, Maximum Movements: Cork Airport Boeing Class Number of per Crash rate (crashes per million ) Crash rate (crashes per ) Average MTWA (tonne) Destroyed area (hectare) NATS MODEL Class I jets 0 1.113 0-0.000 Class II-IV jets (PAX) 56,161 0.148 8.31 E-3 101 0.498 Class II-IV jets (NP) 5,974 0.444 2.65 E-3 87 0.464 Eastern jets 33 0.874 2.92 E-5 42 0.328 Executive jets 5,765 2.23 1.29 E-2 15 0.201 Turboprops T1 (PAX) 28,923 0.288 8.33 E-3 15 0.201 Turboprops T1 (NP) 648 0.864 5.60 E-4 15 0.201 Turboprops T2 2,065 0.782 1.61 E-3 31 0.284 Miscellaneous 3,361 3.27 1.10 E-2 4 0.108 TOTAL 102,930 4.53 E-2 AVERAGE 0.441 33 0.2514 AEA LIGHT AIRCRAFT MODEL Piston engine 50,370 3.27 1.65 E-1 2 0.0775 GRAND TOTAL 153,300 2.10 E-1 Notes 1. Total maximum capacity per. 2. MTWA - maximum take-off weight authorised. 3. PAX - passenger aircraft. 4. NP - non passenger aircraft (e.g. freight). 5. The calculated average crash rate per movement and average destroyed areas are the same as those for 2000 (see Table C2.1). It is judged that the proportions of landings and take-offs in each direction for the future case are equal to those for the 2000. The number of landings and take-offs for the maximum capacity, main runway case are summarised in Table C2.4. C3
Table C2.4 Summary of Movements, Maximum Movements: Cork Airport 7 25 Total 17 35 Total Grand total NATS model Landings 171 2,248 2,419 26,673 22,520 49,193 51,612 4% 51% 55% 27% 23% 50% Take offs 292 1,669 1,961 31,122 18,235 49,357 51,318 7% 38% 45% 32% 19% 50% 102,930 AEA light aircraft model Landings + Take offs 7,140 32,280 39,420 5,064 5,886 10,950 50,370 18% 82% 100% 46% 54% 100% Grand total 7,603 36,197 43,800 62,860 46,640 109,500 153,300 It is recognised that, for practical reasons, all runways at an airport are unlikely to each be operating at its own maximum. Therefore, the total maximum number of for an airport is unlikely to be the sum of the maxima for the individual runways. Similarly, the sum of the maximum take-offs for an airport need not necessarily be the same as the sum of the maximum landings for an airport. Additional information relating to the size of the runways is also required, as summarised in Table C2.5. Table C2.5 Summary of Runway Specific Detail: Cork Airport Runway Length (m) Offset - End 1 (m) Offset - End 2 (m) 7/25 1,310 0 0 17/35 2,133 0 0 Notes 1. The Length detailed here is the length of the tarmac, not accounting for the presence of displaced thresholds. 2. The offset distances are the distances from the end of tarmac to the displaced threshold. Displaced thresholds are not in operation for landings on runways at Cork Airport. See Annex A for more information on displaced thresholds. The number of aircraft for the 2000 and maximum capacity cases are implemented in the method outlined in Section C5 to yield the impact frequency for any point. The results are summarised in Table C6.1. C4
C3 AIRCRAFT CRASH RATE C3.1 AIRCRAFT CLASSIFICATION Examples of the Boeing aircraft classes are summarised in the DETR report and are detailed in Annex A. The aircraft data for Cork Airport, grouped according to the Boeing Classes are summarised in Table C2.3. C3.2 ALL CLASSES MOVEMENT WEIGHTED AVERAGE CRASH RATE Crash frequency results are summarised in Table C2.3 and explained below. Light and large aircraft are considered separately. Note that the example calculations in the following sections have been performed with numbers expressed to more significant figures or decimal places than are shown. Therefore, results from calculations reproduced using rounded numbers may differ slightly from those shown in the following sections. C3.2.1 Crash Rate (Crashes per Year) Each aircraft group has an associated crash rate (crashes per movement) as detailed in the NATS report (1). The crash rate (crashes per ) for each group is calculated from the total per and the crash rate (crashes per movement). For example, using the maximum movement figures for Class II-IV western airliner jets (PAX): Number of per Crash rate (crashes per movement) = Crash rate (crashes per ) 56,161 0.148 E-6 = 8.31 E-3 C3.2.2 Average Crash Rate (Crashes per Movement) An average crash rate (crashes per movement) for large aircraft is calculated accounting for the number of of each aircraft class. The total crash rate (crashes per ) is divided by the total number of annual as, summarised below: Total crash rate Total number of = Average crash rate (per (crashes per ) movement) 4.53 E-2 102,930 = 0.441 E-6 Therefore, the average crash rate is 0.441 per million. (1) Evans, A. W., Foot, P. B. et al. Third Party Risk Near Airports and Public Safety Zone Policy. June 1997. National Air Traffic Services Limited. R&D Report 9636. RDD File Reference 8CS/091/03/10. C5
C3.2.3 Weighted Average Destroyed Area Equation C3.1 The average maximum take-off weight authorised (MTWA) is the calculated mean average for each aircraft class. The weighted average MTWA is weighted according to the number of crashes per for each aircraft class. For example, using the figures for Class II-IV western airliner jets (PAX): Crash rate (crashes per ) Average MTWA (tonne) = Weighted average MTWA (tonne.crashes per ) 8.31 E-3 101 = 0.8395 The destroyed area is calculated from the following relationship detailed in the NATS report and Annex A: A ln 10000 6.16 0.474ln W ln, BC i where A BC,i W area destroyed (m²) MTWA (kg) For example, using the MTWA for Class II-IV western airliner jets (PAX) (101 tonne or 101,000 kg): ln(a) = 9.21-6.16 + 0.474 ln(101,000) = 9.21-6.16 + 0.474 11.523 ln(a) = 9.21-6.16 + 5.462 = 8.512 A = e 8.512 A = 4,975 An average destroyed area is calculated accounting for the crash rate of each aircraft class. The destroyed area for each class is multiplied by its proportion of the total crash rate (crashes per ). This is equivalent to summing the product of the crash rate (crashes per ) and destroyed area for each of the large aircraft classes, as summarised below: Crash rate (crashes per ) Destroyed area (hectare) = Weighted destroyed area (hectare.crashes per ) Class I jets 0 N/A = 0 Class II-IV jets (PAX) 8.31 E-3 0.498 = 4.14 E-3 Class II-IV jets (NP) 2.65 E-3 0.464 = 1.23 E-3 Eastern jets 2.92 E-5 0.328 = 9.59 E-6 Executive jets 1.29 E-2 0.201 = 2.59 E-3 Turboprops T1 (PAX) 8.33 E-3 0.201 = 1.68 E-3 Turboprops T1 (NP) 5.60 E-4 0.201 = 1.13 E-4 C6
Turboprops T2 1.61 E-3 0.284 = 4.59 E-4 Miscellaneous 1.10 E-2 0.108 = 1.18 E-3 Total 1.14 E-2 Total weighted destroyed Total crashes = Average destroyed area per area (hectares) 1.14 E-2 4.53 E-2 = 0.2514 Assuming the destroyed area is square, the average destroyed area (0.2514 hectares or 2,514 m²) is represented by a square whose side is 50.1 m. Similarly, the destroyed area for light aircraft is calculated as 0.0775 hectares (775 m²), which approximates to a square of side 27.8 m. C3.2.4 Type of Crash In both the NATS and the DETR reports, the proportions of the four types of crash were estimated as follows: take-off crashes from flight, 20% take-off overruns, 8% landing crashes from flight, 52% and landing overruns, 20%. The average crash rate is apportioned to the four types of crash as summarised in Table C3.1. For example, for take-off crashes from flight: Average crash rate (crashes per million ) Proportion of take-off crashes from flight = Average crash rate for take-off crashes from flight (crashes per million ) 0.441 0.20 = 0.0881 The model for light aircraft does not distinguish between take-off and landing crashes, therefore a combined (i.e. take-off and landing) crash rate is used. Table C3.1 Summary of Crash Rates (All Aircraft Classes): Cork Crash rate per million Crashes Overruns Total NATS model Landings 0.2291 0.0881 0.3172 Take-offs 0.0881 0.0352 0.1233 AEA light aircraft model Total N/A N/A 3.27 Notes 1. N/A - not applicable. The light aircraft model does not distinguish between crashes and overruns. C7
C3.3 ANNUAL CRASH RATE FOR EACH CRASH MODE The annual crash rate is related to the number of on a given runway. The numbers of annual maximum for each runway are summarised in Table C2.4. As an example, the number of maximum, associated with the main runway (17/35) are shown schematically in Figure C3.1. Figure C3.1 Schematic of Maximum Large Aircraft Movements Associated with the Main Runway (17/35) End 17 Take-offs 18,235 19% Landings 26,673 27% Landings 22,520 23% Take-offs 31,122 32% End 35 C8
Figure C3.2 Schematic of Maximum Light Aircraft Movements Associated with the Existing Main Runway (17/35) End 17 Landings+Take-offs 5,886 54% Landings+Take-offs 5,064 46% End 35 For a point at End 35, the following crash rates are calculated (1) (2) : Take-off overrun (A) Take-off overrun crash rate (crashes per movement) Number of = Crash rate per (0.0352 1,000,000) 31,122 = 1.10 E-3 Landing overrun (A) Landing overrun crash rate (crashes per movement) Number of = Crash rate per (0.0881 1,000,000) 26,673 = 2.35 E-3 Take-off crash (non overrun) (A) Take-off non overrun crash rate (crashes per movement) Number of = Crash rate per (0.0881 1,000,000) 31,122 = 2.74 E-3 (1) Crash rates associated with where the calculation point is after and before the runway (relative to the movement) are indicated by the letter A and B, respectively. (2) For individual risk calculation other than alongside the runway, take-off and landing overruns are only considered when the direction of landing or take-off is towards the calculation point. Therefore, only crash rates indicated by A are detailed. C9
Take-off crash (non overrun) (B) Take-off non overrun crash rate (crashes per movement) Number of = Crash rate per (0.0881 1,000,000) 18,235 = 1.61 E-3 Landing crash (non overrun) (A) Landing non overrun crash rate (crashes per movement) Number of = Crash rate per (0.2291 1,000,000) 26,673 = 6.11 E-3 Landing crash (non overrun) (B) Landing non overrun crash rate (crashes per movement) Number of = Crash rate per (0.2291 1,000,000) 22,520 = 5.16 E-3 Light aircraft (Runway 17) Take-off overrun crash rate (crashes per movement) Number of = Crash rate per (3.27 1,000,000) 5,064 = 1.66 E-2 Light aircraft (Runway 35) Take-off overrun crash rate (crashes per movement) Number of = Crash rate per (3.27 1,000,000) 5,886 = 1.92 E-2 C3.4 LONGITUDINAL AND LATERAL DISTANCE CALCULATION Consider calculation at a point at End 35 as illustrated in Figure C3.1. C10
Figure C3.1 Representative Runway Diagram Take-off Direction 17 Point of interest y = -2133 y -ve y = 0 y +ve x +ve x +ve 17 Runway of length 2133 metres 35 125 50 y +ve y = 0 y -ve y = -2133 Take-off Direction 35 Landing Direction 17 Point of interest y -ve y = 0 y +ve y = 2133 x +ve x +ve 17 Runway of length 2133 metres 35 y = 2133 y +ve y = 0 125 y -ve 50 Landing Direction 35 Notes 1. The schematic is not to scale. 2. It is understood that there is no displaced threshold on Runway 17/35 at Cork Airport. Therefore, the runway origin is taken as the end of the tarmac. For the point illustrated in Figure C3.1, at the south of Runway 17/35 (i.e. End 35), the values of x and y are defined for each crash mode as summarised in Table C3.2. The length of 17/35 Runway is given as 2,133 m. Therefore, the longitudinal distance of the sample point, for a landing overrun is: Runway length (m) + Distance from runway = Longitudinal threshold (m) distance (m) 2,133 + 125 = 2,258 Similarly, for a landing crash (non overrun) (B), the longitudinal distance of the sample point, for a landing overrun is: - Distance from runway threshold (m) = Longitudinal distance (m) -125 = -125 Table C3.2 Summary of Lateral and Longitudinal Coordinates Crash mode Lateral, x (m) Longitudinal, y (m) Take-off overrun 50 125 Landing overrun 50 2,258 Take-off crash (non overrun) (A) 50 125 Take-off crash (non overrun) (B) 50-2,258 Landing crash (non overrun) (A) 50 2,258 Landing crash (non overrun) (B) 50-125 C11
C4 IMPACT PROBABILITY CALCULATION Impact probability can be calculated at any point from the integrals of the Probability Density Functions (PDFs) given in Annex A and aircraft crash rates calculated in Section C3. C4.1.1 Take-off Overrun - Wreckage Location Sample Calculation For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 7.290 E-3, for y = 125 m and x = 50 m. C4.1.2 Landing Overruns - Wreckage Location Sample Calculation (A) For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 2.599 E-3, for y = 2,258 m and x = 50 m. C4.1.3 Take-off Crash (non overrun) Sample Calculation (A) For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 2.170 E-3, for y = 125 m and x = 50 m. Sample Calculation (B) For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 2.115 E-4, for y = -2,258 m and x = 50 m. C4.1.4 Landing Crash (non overrun) Sample Calculation (A) For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 8.258 E-5, for y = 2,258 m and x = 50 m. Sample Calculation (B) For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 1.740 E-3, for y = -125 m and x = 50 m. C4.1.5 Light Sample Calculation (Runway 17) For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 1.278 E-6, for y = 125 m and x = 50 m. C12
Sample Calculation (Runway 35) For the sample point illustrated in Figure C3.1, the integral of the PDF is calculated as 4.093 E-5, for y = 125 m and x = 50 m. C13
C5 INDIVIDUAL RISK CALCULATION The individual risk (IR) at any point can be calculated by summing the products of the crash frequency (detailed in Section C3) and impact probability (summarised in Section C4), for each crash mode. For the sample point illustrated in Figure C3.1, at south end of runway 17/35 (End 35), the calculation is as follows: Crash rate per PDF Integral = Crash frequency per Take-off overrun (A) 2 1.10 E-3 7.290 E-3 = 1.60 E-5 Landing overrun (A) 2 2.35 E-3 2.599 E-3 = 1.22 E-5 Take-off crash (non overrun) (A) 2 2.74 E-3 2.170 E-3 = 1.19 E-5 Take-off crash (non overrun) (B) 2 1.61 E-3 2.115 E-4 = 6.81 E-7 Landing crash (non overrun) (A) 2 6.11 E-3 8.258 E-5 = 1.01 E-6 Landing crash (non overrun) (B) 2 5.16 E-3 1.740 E-3 = 1.80 E-5 Light aircraft (Runway 17) 1.66 E-2 4.093 E-5 = 6.79 E-7 Light aircraft (Runway 35) 1.92 E-2 1.278 E-6 = 2.45 E-8 Total 6.06 E-5 This value (6.06 E-5) represents the annual individual risk for the sample point illustrated in Figure C3.1. C14
C6 CALCULATION OF THE PUBLIC SAFETY ZONE TRIANGLES The Public Safety Zones (PSZs) are calculated based on the maximum movement data. Light aircraft are not included in the calculation of the outer PSZ. The maximum width calculation method is described in Annex A. The distance (Y mw ) along the extended runway centreline from End 35 where the annual individual risk is calculated as 1 E-6 is 11,015 m. The distance (X mw ) perpendicular to the extended runway centreline at which the individual risk is calculated as 1 E-6 is 505 m. The distance (Y mw ) along the extended runway centreline where the maximum width occurs is 470 m. The triangle base width for the PSZ (corresponding to an annual individual risk of 1 E-6) is calculated as 1,055 m, as follows. Equation C6.1 X max 11015 505 527.5 11015 470 The triangle base width is double X max. The Public Safety Zone results for each runway corresponding to the maximum are summarised in Table C6.1. Table C6.1 Summary of PSZ Dimensions: Cork PSZ triangles Airport and Runway Length (m) Width (m) Area (km²) CORK (maximum ) 7 (west end) 10-4 N/A N/A N/A Inner 625 96 0.030 Outer 2,615 223 0.292 25 (east end) 10-4 N/A N/A N/A Inner 625 96 0.030 Outer 2,300 169 0.195 17 (north end) 10-4 660 75 0.025 Inner 3,065 261 0.399 Outer 11,290 962 5.432 35 (south end) 10-4 730 74 0.027 Inner 3,055 278 0.425 Outer 11,015 1,055 5.811 Notes 1. Inner and outer PSZs relate to annual individual risks of 10-5 and 10-6 per respectively. 2. N/A not applicable. Individual risk of 10-4 per is not reached at the ends of Runway 7/25. C15