A computer reservations
system (CRS) is a computerized system used to store and retrieve
information and conduct transactions related to air travel. Originally
designed and operated by airlines, CRSes were later extended for
the use of travel agencies; major CRS operations that book and sell
tickets for multiple airlines are known as global distribution systems.
Airlines have divested most of their direct holdings to dedicated
GDS companies, who make their systems accessible to consumers through
Internet gateways. Modern GDSes typically allow users to book hotel
rooms and rental cars as well as airline tickets or train tickets.
The Airline Reservations System (ARS) was one of the earliest changes
to improve efficiency. ARS eventually evolved into the Computer Reservations
System (CRS). A Computer Reservation System is used for the reservations
of a particular airline and interfaces with a Global Distribution
System (GDS) which supports travel agencies and other distribution
channels in making reservations for most major airlines in a single
The history of airline reservations systems began in the late 1950s
when American Airlines required a system that would allow real-time
access to flight details in all of its offices, and the integration
and automation of its booking and ticketing processes. As a result,
Sabre (Semi-Automated Business Research Environment) was developed
and launched in 1964. Sabre's breakthrough was its ability to keep
inventory correct in real time, accessible to agents around the world.
Prior to this, manual systems required centralized reservation centers,
groups of people in a room with the physical cards that represented
inventory, in this case, seats on airplanes.
The deregulation of the airline industry, in the Airline Deregulation
Act, meant that airlines, which had previously operated under government-set
fares ensuring airlines at least broke even, now needed to improve
efficiency to compete in a free market. In this deregulated environment
the ARS and its descendants became vital to the travel industry.
access an airline’s inventory through an availability display.
It contains all offered flights for a particular city-pair with
their available seats in the different booking classes.It contains
all offered flights for a particular city-pair with their available
seats in the different booking classes. This display contains flights,
which are operated by the airline itself as well as code share
flights which are operated in co-operation with another airline.
The availability of seats of other airlines is updated through
standard industry interfaces. Depending on the type of co-operation
it supports access to the last seat (Last Seat Availability) in
real-time. Reservations for individual passengers or groups are
stored in a so-called Passenger Name Record (PNR). Among other
data, the PNR contains personal information such as name, contact
information or special services requests (SSRs) e.g. for a vegetarian
meal, as well as the flights (segments) and issued tickets. Some
reservation systems also allow to store customer data in profiles
to avoid data re-entry each time a new reservation is made for
a known passenger. In addition most systems have interfaces to
CRM systems or customer loyalty applications (aka Frequent Traveler
Systems). Before a flight departs the so-called Passenger Name
List (PNL) is handed over to the Departure Control System that
is used to check-in passengers and baggage. Reservation data such
as the number of booked passengers and special service requests
is also transferred to Flight Operations Systems, Crew Management
and Catering Systems. Once a flight has departed the reservation
system is updated with a list of the checked-in passengers (e.g.
passengers who had a reservation but did not check in (No Shows)
and passengers who checked in, but didn’t have a reservation
(Go Shows)). Finally data needed for revenue accounting and reporting
is handed over to the administrative systems.