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41 subjective assessment and the use of some simplification to Table 15. Example normal operation run the risk analysis. on Runway 07, hypothetical airport. For the RSA configuration in the example, there are only Parameter Value Note four crash scenarios that may lead the aircraft to fall into the Aircraft B738 Boeing 737-800 Equipment Class N Large jet water if overrunning or undershooting the runway: User Class C Commercial Crash Scenario 1. During a landing or takeoff operation on Equipment Type J Jet Runway 07, the aircraft will overrun the RSA within its 500 ft Wind Direction 340 Wind Speed Knts 13 wide boundaries and fall after running 100 ft. Ceiling ft 500 Crash Scenario 2. During a landing on Runway 25, the air- Visibility Sm 1.0 craft will undershoot the RSA within 500 ft wide boundaries Temperature C 30 Fog 1 Fog present and before the RSA end, 100 ft from the threshold. Icing 0 No icing Crash Scenario 3. Same as Crash Scenario 1, but the aircraft Elec. Storm 0 No elect. Storm will fall into the water outside the 500 ft wide boundaries of Frozen Precipitation 0 No frozen precip. Snow 0 No snow the RSA. XWind Knts 13 calculated Crash Scenario 4. Same as Crash Scenario 3, but the aircraft Rain 0 No rain will undershoot before the runway end and outside the 500 ft Foreign Origin/Dest. 0 Domestic Significant Terrain 0 No significant terrain wide boundaries of the RSA. It should be noted that the small number of crash scenar- ios identified is for this simple example only. The presence of b = -15.456 + 0.551(0) - 2.113(0) - 1.064(0) - 0.876(00) obstacles or the asymmetry of the RSA would lead to addi- +0.445(0) - 0.857(0) + 1.832(1) + 1.639(0) + 2.428(1) tional possible crash scenarios. For example, if the RSA had +1.186(0) + 1.741(0) + 0.322(0) - 0.532(0) + 1.566(0) an ILS structure, two additional crash scenarios should be +1.518(1) + 0.986(0) + 1.926(0) + 1.499(0) - 1.009(0) considered: -0.631(0) + 0.265(1) + 1.006(0) + 0.924(0) = -9.413 Crash Scenario 5. During a landing or takeoff operation on The probability that an aircraft will not be able to stop dur- Runway 07, the aircraft will overrun the RSA within the cen- ing a landing operation and overrun the runway under these ter area of the RSA and hit the ILS structure with enough conditions is therefore computed as follows: energy for severe consequences. Crash Scenario 6. Same as Crash Scenario 5, but the aircraft 1 P{LDOR} = = 8.165 10-5 will undershoot in the RSA, before the ILS structure and 1 + e 9.413 strike it. As expected, the risk of an incident is high for such unfa- In this case, Crash Scenario 1 should be modified so that vorable conditions: strong cross wind, low visibility, and low the aircraft would overrun or undershoot the runways ceiling. After calculating the likelihood of an overrun, the between the RSA 500ft boundaries in a path that avoids the next step in the process is to estimate probability the aircraft ILS structure and the aircraft falls into the water. No modi- will stop beyond the RSA or hit an existing obstacle. fication would be required for Crash Scenario 2, when the The area surrounding the RSA is a body of water. In this aircraft undershoots the runway before the beginning of case, it is possible to assume the aircraft will be lost if it over- the RSA. runs the RSA and falls into the water. Distance x from the runway end is simply the length of RSA measuring 100 ft, and Step 4--Estimate the Risk this is the value to be entered in the normalized x-location model given by Equation 13. It should be noted that the For each operation in the NOD sample, it is necessary to parameter "" from general Equation 25 in this case should calculate the risk. An example calculation for one landing op- be set to 0 because the aircraft will fall into the water if its stop eration will be described to help understanding of the location simply exceeds 100 ft beyond the threshold. process. The calculation is given by: Suppose one of the landing operations on Runway 07 is characterized by the parameters depicted in Table 15. P{d > x} = e -0.004692 x 0.824513 The information is used in Equation 7 to compute P{d > x} = e -0.0046921000.824513 = 81% the probability the aircraft will overrun Runway 07 during a landing operation under these conditions, thus challeng- The probability an aircraft will end in the water if over- ing the RSA being evaluated. The computation is the running the runway during landing is high because the RSA following: is very short.