Case study B: Airline
The airline runs scheduled flights between cities, where each flight is scheduled to depart from a departure airport at a specific departure date and time from a specific gate, and arrive at the arrival airport after a period of time required to fly from the departure city to the arrival city.
Each flight is scheduled on a specific aircraft type, where seats are arranged in a different way on each aircraft type. Seats are divided among two cabins, first class and coach. Each seat has a seat number that identifies its position in the aircraft. Each seat also has a row location, designating whether it is a window, middle, or aisle seat.
The airline has a frequent flier program that provides free award flights and first-class upgrades. A customer may be a member of the frequent flier program, or not. A member can be either a Gold, Silver, or Bronze level member, depending on the number of miles flown on the airline. A member earns a specific number of “miles” (frequent flier credits) for each flight flown, depending on the length of the flight.
Members may request first-class upgrades up to three hours prior to a flight. Half an hour before a flight is scheduled to depart, first-class upgrades are offered on a space-availability basis first to members who requested upgrades on a priority basis: Gold level members, then Silver, then Bronze. Members may request companion upgrades for fellow travelers, paid for with frequent flier credits.
A customer reserves a flight through an online interface. First, the customer enters the desired parameters of travel: departure and destination airports, dates for departure and return, number of people traveling in the party. The customer browses the available flights (the customer should only see flights where there are sufficient available seats to accommodate the entire traveling party), makes a selection, chooses seats, and pays. At any stage before the transaction is complete, the customer can go back and modify dates, flights, or seats. After the transaction is complete, the customer receives an itinerary and receipt via email. As a part of transaction processing, specific seats are reserved on the flight, and become unavailable to other potential customers.
A customer reserves a specific class of ticket, which determines the price of the ticket purchased and policies related to change fees and eligibility for refund. A pricing schedule determines the price for each route and class of ticket. For example, a non-refundable economy ticket purchased several months in advance will differ in price from a refundable economy ticket purchased a few days before the flight.
A reservation may be for a party of people, rather than for an individual. While the reservation may refer to multiple people, each individual within the party is issued a separate ticket associated with a specific seat on the aircraft.
Award flights are available to members through the airline’s online reservation system. The process follows the regular reservation workflow, except that the customer pays with “miles” rather than money.
A customer may change a reservation (date or time of travel, or destination). In this case, any penalties associated with the change (based on the change/refund policy associated with the specific class of ticket purchased) and any difference in fare must be paid at the time of change.
When a customer arrives at the airport for a flight, he/she first checks in. At check in time, each passenger receives a boarding pass and checks in his/her baggage. The allowable number of bags and total baggage weight per person is limited; customers exceeding the number or weight limits are charged an extra fee, which varies depending on how many or how many extra pounds of baggage the customer is checking. Each bag is assigned a tracking number, which is