Crash Location Probabilities for Near-airport Operations - Continued

DOE-STD-3014-96

APPENDIX B

aircraft, the estimated crash location probability values for takeoff and landing crashes

are provided in Tables B-10 and B-12 when the pattern side is on the right side of the

runway, and in Tables B-11 and B-13 when the pattern side is on the left side of the

runway.

A comparison of the military aviation tables with those for commercial aviation

indicates significant differences between the areas where takeoff and landing crashes

are expected to occur. In commercial aviation, landing crashes end just about a mile

from the origin (center of the runway). In military aviation, landing crashes are more

widespread and extend up to 10 miles beyond the end of the runway. These

differences are driven by the assumptions made in the classification of crashes. For

military crashes, takeoffs are defined as the instant the aircraft lifts from the runway

until the time it transitions to climb to cruise altitude. If an aircraft crashes after takeoff

with no control capability, it is considered a takeoff crash. However, if an aircraft gets

into trouble during takeoff and the pilot is able to turn the aircraft for an attempted

emergency landing but crashes prior to a successful landing, it is considered a landing

crash. Therefore, an aircraft which has taken off from one end of the runway could

crash miles away from that end of the runway but still be classified as a landing crash.

This is why the takeoff crash location probability values for military aviation are

concentrated along the extended centerline of a runway, and those for the landing

crashes are spread out. In addition, because the downwind leg is parallel to, but some

distance away from, the runway, the landing probability values would not necessarily

monotonically decrease with increasing values of y, as is the case for commercial

aviation. Since the identification of crashes used to estimate the crash rates and

location probability values is consistent within each of the categories, military and

commercial, differences in the shape of the location distributions for military and

commercial aviation are realistic and do not affect the overall impact frequency

calculations.

The crash location probability values represent the conditional probability, given a

crash, of a crash into an area of one square mile. The analyst would use the facility's

B-9