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a connecting flight. A direct flight or through flight
is operated by the same aircraft and includes at least
one intermediate stop; passengers stay on board dur-
ing the trip. Note that the flight number remains the
same throughout the trip. A connecting flight requires
an aircraft change for passengers in a hub. Thus, the
trip includes at least two different planes with two dif-
ferent flight numbers. A Trip is a sequence of flight
legs taken by passengers to complete a journey.
The problem of allocating a new flight concerns
the first two questions of airline schedule design, that
is, determining a set of OD pairs and then choosing
the arrival and departure times for an aircraft, given
certain constraints, that minimize costs and maximize
the profit of an airline company.
Adding a new flight leg to the current network is
complicated and involves several decisions:
• Scheduling decisions must be made according to
all flight legs connected with the new addition
flight leg. They must decide which flight leg to
add after considering competitors.
• Measuring Route ’Profitability’: determines eco-
nomic profitability of opening a new flight, if it
involves a new destination. The other costs must
be considered including the additional cost of the
airport and also calculate the prices in order not
to lose their passengers but to capture a new de-
mand. That depends on the existence of current
routes that could be connecting flight as well as
expected future competition.
In this work, we aim to determine a set of (OD) pairs
for allocating new flights. This problem evokes the
selection of routes to be flown but some operational
and economic considerations must be taken to op-
timize an airline network. A route is a sequence
of flights with unique flight numbers that begins at
the origin airport and ends at the destination airport.
Therefore, a forecasting demand is required to esti-
mate passenger demand for each route and then de-
termine the expected cost and finally compute flight
time and revenue. Forecasting demand is the key ele-
ment while an airline is planning to add a new flight.
An airline needs to estimate the total number of pas-
sengers who are willing to take this route, especially
if the route is already operated by other airlines. It
has to supply enough seats to satisfy the demand. On
the one hand, we deal with retrieving set of origin-
destination pairs. On the other hand, we look for the
best itineraries based on three principal criteria of QSI
models (Quality of Service Index) which let airlines
project potential market share impact on each deci-
sion. QSI model is a market share model that is used
to estimate the probability that a traveler selects a spe-
cific itinerary connecting an airport pair (Jacobs et al.,
2012). Two KPIs (Key Performance Indicator) are
considered in potential market share impact: number
of passengers and revenue for the airline company,
that is, adding a new flight by allocating capacities
to maximize the revenue.
1.1 State of the Art
The air transportation industry has evolved rapidly
over the last years. Route network development,
schedule design, fleet assignment, aircraft mainte-
nance routing and crew scheduling that represent the
five facets of the air transportation optimization prob-
lem (Rebetanety, 2006):
Route Network Development: deciding which set
of origin-destination pairs to serve. The network
design problem consists of determining where to
fly (Belobaba et al., 2015).
Schedule design : defining the frequency of each
flight. Scheduling determines where and when the
airline will fly.
Fleet Assignment: specifying the type and the size
of aircraft serving each flight in a given schedule
(Rebetanety, 2006).
Aircraft Routing: determining feasible aircraft
routes, sequences of flight legs flown by an air-
craft type under maintenance and time constraints
(Jacobs et al., 2012).
Crew Scheduling: assigning crews to the flights.
Airlines have the choice to create new routes or in-
crease/decrease the frequency of exiting routes with
respect to operational and economic constraints. The
latter does not require the route network develop-
ment since the route already exists. Note that cre-
ating a new route requires a lot of investment (Car-
mona Benitez, 2012). Relevant literature exists for
airline scheduling and routing. Most researches deal
with minimization of the airline cost. (Dobson and
Lederer, 1993) studied profit maximization with re-
spect to quality of service and modeled flight sched-
ules including company costs and consumer choice.
The objective was to maximize profit against fixed
schedules and prices for other airlines, demand was
calculated for each route as a function of the ser-
vice quality of all routes to attract passengers. They
used a heuristic algorithm to calculate optimal sched-
ules and prices with two classes of customers busi-
ness and non-business and solved a sample problem
with 12-period and 5-city which gives 120 flights and
20 (OD). The competition between airlines has in-
creased. In order to deal with competition, airlines
have to increase their market share. In this regard,
QSI criteria are integrated in our model to get poten-
tial market share impact for an airline. Figure 1 shows
DCORES 2017 - DOCTORAL CONSORTIUM
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