Abstract:
The air transportation system is a significant "engine" of the U.S. economy providing
rapid, safe, secure, affordable transportation over large geographic distances. Growth in
passenger and cargo transportation demand (i.e. flights) in excess of the growth in air
transportation capacity (i.e. runways, airspace sectors) has resulted in massive systemic
delays. These delays are estimated in 2007 to have cost passengers up to $12 billion, and
to have cost the airlines $19 billion in excess direct operating costs. With the current trend
in rising fuel prices, the economic impact of these delays is expected to strain the U.S.
economy even more. These delays also contribute to local air and water quality issues and
to global climate change.
Systematic solutions to address the imbalance between scheduled demand and forecast
capacity include: (1) increasing capacity through the construction of new airports and additional runways at existing airports, (2) better utilization of existing capacity by increasing
throughput productivity through advanced satellite-based navigation and 4-D trajectory
planning, (3) demand management through administrative measures (such as the High
Density Rule) and market-based mechanisms (such as congestion pricing and auctions of
airport and airspace slots). Solutions 1 and 2 are capital intensive and require decades of
planning and development. Solution 3 can be implemented rapidly but faces strong political
opposition.
In the absence of scheduling flights within the constraints of the capacity, flights arriving
at an airport in excess of the airport arrival capacity are delayed until an arrival slot is
available. Traditionally, flights that needed to be delayed were required to fly "holding
patterns" above the airport until an arrival slot became available. To avoid these foreseen
airborne holding delays, and to increase safety, the U.S. Air Traffic Control system runs a
Ground Delay Program (GDP). The GDP holds the flights on the ground at their origin
airports, allowing them to depart only when arrival slots will be available at the time the
°ight is estimated to arrive at the constrained destination airport. Although the GDP was
originally designed to manage reductions in capacity due to weather, over the last decade
the GDP is routinely used to manage systemically over-scheduled arrivals.
The GDP rations the available airport arrival capacity based on scheduled arrival times
of flights (i.e. first-scheduled, first served). Special care is taken to equitably distribute
delays between airlines. The Ration-by-Schedule approach is "airline flight-centric" and
does not explicitly take into account passenger trip delays, fuel flow effciency, and emissions.
Previous research evaluated alternate rationing rules using airline-flight centric metrics.
The objective of this research is to examine the impact of alternative GDP rationing rules
on the performance and equity to airlines and passengers. The hypothesis is that alternate
GDP rationing rules can maximize the mutual interests of both airlines and passengers.
This dissertation describes the GDP Rationing Rule Simulator (GDP-RRS) that was
developed to evaluate alternate rationing rules. The dissertation also describes the results
of three experiments conducted for flights affected by GDPs in 2007 for arrivals at the three
New York Metroplex airports (Newark Liberty (EWR), LaGuardia (LGA) and John F.
Kennedy (JFK) airports). The first experiment compared the performance and equity of five
alternate rationing rules to the Ration-by-Schedule rationing rule. The second experiment
evaluated the impact of substitution strategies in the GDP rationing rules. The third
experiment investigated the impact of GDP scope on performance and equity for airlines
and passengers.
The major findings of the research are:
* It is not possible to maximize the mutual interests of airlines and passengers. There exists a tradeoff between GDP performance and equity (see
below).
* When only performance is considered (and equity for both airlines and passengers are ignored), the best rationing rule is Ration-by-Passengers. This
rule maximizes passenger throughput. Passengers experience a reduction
in passenger delays of 23% at EWR, 20% at LGA, 15% at JFK relative to
the Ration-by-Schedule rule. Airlines experience savings of 57% fuel burn
at EWR, 63% at LGA, 42% at JFK relative to the Ration-by-Schedule
rule.
* When only equity due to flight and passenger delays are considered (and
performance of both airlines and passengers are ignored), the rule that
provides the best equity is Ration-by-Schedule.
* When performance and equity of flight delays for airlines are considered (and performance and equity for passengers are ignored), the rules that provide the best performance differs by airport: Ration-by-Passengers at EWR, Ration-by-Aircraft Size at
LGA, and Ration-by-Distance at JFK.
* When performance and equity for passengers are considered (and performance and
equity for airlines are ignored), the rules that provide the best performance differ by
airport: Ration-by-Distance at EWR and LGA and Ration-by-Passengers or Ration-
by-Fuel Flow High Precedence at JFK.
* When performance and equity for both airlines and passengers are considered, the
rules that provide the best performance and equity differs by airport: Ration-by-
Distance at EWR, Ration-by-Aircraft Size at LGA, and Ration-by-Passengers at JFK.
* Airline equity is determined by the flight schedule (i.e. position of flights throughout
the day) and the aircraft type (i.e. fleet mix).
* Passenger equity is determined by the flight cancellations.
* Airlines with a small number of operations and airports with a small number of
enplanements, experience disproportional performance and equity penalties.
* Airline substitution strategies do not change the relative performance and equity of
the alternate rationing rules.
* Changes in GDP scopes do not change the relative performance and equity of the
alternate rationing rules. Scope is the distance range of the GDP.
* The selection of the GDP rationing rule requires the unambiguous definition of the
National Air Transportation System objectives (and the weights for the performance
and equity). The relative weighting of objectives is a social and political activity.
The application of alternate GDP rationing rules has broader implications. GDP rationing rules create priority queues which give preference to the compliant flights. As a
consequence the rationing rules incentivize airline behavior related to scheduling and fleet
mix. For example, the Ration-by-Passengers rule could, in the long-run, result in the migration of airline fleets to larger sized aircraft that would increase the passenger flow capacity.
This would improve the efficiency of the air transportation system. This incentive would
result in an increase in aircraft size, which would lead to reduced frequency, which would
yield lower delays.