CONCLUSIONS
This paper uses recorded actual flight data to evaluate the height that an aircraft will cross the
centerline of the proposed PT. In the past, there have been numerous studies to determine
aircraft height using mathematical models; however, the mathematical models do not consider
the human interface in the operation of an aircraft. This study considers the actual aircraft flight
path operated by an operator (pilot) given the visibility, weather and other conditions that existed
and are difficult to account for in the modeling process. In their decision document #7, AOSC
[5] suggests that the aircraft operators should be made aware of the PT operations at DFW and
appropriate training given to efficiently execute the take off maneuver and decent maneuver over
the PT while aircraft are traversing the PT.
Using a conservative assumption of a normal distribution, this study estimates the risk
(probability) of an aircraft failing to meet the minimum threshold heights established by the FAA
above the centerline of the PT. The results indicate that the arrival paths pose a lower risk on
average; however, runway 35C has an estimated probability of flying below the threshold of
0.000015. Runway 35L has the highest probability of failing to meet the departure threshold,
which is 0.000029. With failure probabilities this low, the proposed PT seems to be located at a
sufficient distance from the end of the runway for safe arrival and departure operations. After
construction of the PT, another flight path study should be undertaken to determine if the PTs
existence has any impact on the flight paths.
If this risk analysis does not provide a sufficient level of confidence in the safety of the
operation, additional research can be undertaken to quantify the risk with a more thorough
approach. The authors believe the failure probabilities will continue to decrease due to some
Satyamurti and Mattingly
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conservative assumptions in this analysis. Specific issues to consider include: increasing the
number of days considered in the databases, the probability of an aircraft being on the PT in the
flight path, which will definitely not be guaranteed as assumed by this study, and a more accurate
representation of the lower tail of the flight path height distribution, which may lack the
characteristics of the normal distribution in this region due to the paucity of observations. The
probabilities estimated in this paper can be further evaluated to arrive at the probable safe
distance for PT construction at other airports, like O’Hare (ORD), Los Angeles (LAX) and
Detroit (DTW). Given that these airports may have different flight paths, a similar analysis can
be undertaken using the flight path data from the respective airports. Finally, this risk analysis
serves as a starting point for including a risk assessment for the FAA policies guiding PT design
and construction.
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