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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 -0.004692×1000.824513 = 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.
