Programmed Airline Reservations System (PARS) is an IBM proprietary large scale airline reservation application, a

computer reservations system Computer reservation systems, or central reservation systems (CRS), are computerized systems used to store and retrieve information and conduct transactions related to air travel, hotels, car rental, or other activities. Originally designed and oper ...

, executing under the control of

IBM Airline Control Program IBM Airline Control Program, or ACP, is a discontinued operating system developed by IBM beginning about 1965. In contrast to previous airline transaction processing systems, the most notable aspect of ACP is that it was designed to run on most m ...

(ACP) (and later its successor,

Transaction Processing Facility Transaction Processing Facility (TPF) is an IBM real-time operating system for mainframe computers descended from the IBM System/360 family, including zSeries and System z9. TPF delivers fast, high-volume, high-throughput transaction processin ...

(TPF)). Its international version was known as ''IPARS''.Hobson S.J. "ALCS — A high-performance high-availability DB/DC monitor", 1989. By the 1960s, with the

American Airlines American Airlines is a major airlines of the United States, major US-based airline headquartered in Fort Worth, Texas, within the Dallas–Fort Worth metroplex. It is the Largest airlines in the world, largest airline in the world when measured ...

SABRE A sabre ( French: �sabʁ or saber in American English) is a type of backsword with a curved blade associated with the light cavalry of the early modern and Napoleonic periods. Originally associated with Central European cavalry such as th ...

reservations system up and running, IBM offered its expertise to other airlines, and soon developed Deltamatic for

Delta Air Lines Delta Air Lines, Inc., typically referred to as Delta, is one of the major airlines of the United States and a legacy carrier. One of the List of airlines by foundation date, world's oldest airlines in operation, Delta is headquartered in Atla ...

on the IBM 7074, and PANAMAC for

Pan American World Airways Pan American World Airways, originally founded as Pan American Airways and commonly known as Pan Am, was an American airline that was the principal and largest international air carrier and unofficial overseas flag carrier of the United States ...

using an

IBM 7080 The IBM 7080 was a variable word length BCD transistor computer in the IBM 700/7000 series commercial architecture line, introduced in August 1961, that provided an upgrade path from the vacuum tube IBM 705 computer. The 7080 weighed about . ...

. By 1967/8 IBM generalized its airline reservations work into the PARS system, which ran on the larger members of the IBM

System/360 The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applica ...

family and which could support the largest airlines' needs at that time (e.g. United Airlines ran about 3000 reservations terminals online in the 1972 timeframe). In the early 1970s IBM modified its PARS reservations system so it could accommodate the smaller regional airlines on smaller members of the 370 systems family. The high performance PARS operating system evolved from ACP (''Airlines Control Program'') to TPF (''Transaction Processing Facility''). In the early days of automated reservations systems in the 1960s and 1970s the combination of ACP and PARS provided unprecedented scale and performance from an on-line real-time system, and for a considerable period ranked among the largest networks and systems of the era. In the early 1970s major US banks were developing major on-line teleprocessing applications systems and were in urgent need of ACP's high performance capabilities. ACP was made available by IBM to the banking industry in the mid-1970s. This system was used by the great majority of large airlines in the US and internationally; and its smaller 1970's version was used by many smaller regional airlines. PARS (and IPARS) was extremely successful, and it massively improved and revolutionized the efficiency of airlines passenger operations and their profitability. Along with many other major and regional US airlines, the PARS system was later used by

TWA Trans World Airlines (TWA) was a major American airline which operated from 1930 until 2001. It was formed as Transcontinental & Western Air to operate a route from New York City to Los Angeles via St. Louis, Kansas City, and other stops, with ...

and

Northwest Airlines Northwest Airlines Corp. (NWA) was a major American airline founded in 1926 and absorbed into Delta Air Lines, Inc. by a merger. The merger, approved on October 29, 2008, made Delta the largest airline in the world until the American Airlines ...

.Weiner, Eric
"Diagrams of the Pan Am's and NWA's 1988 route system"
The New York Times, Sunday, June 11, 1989 In this context PARS was also used as a marketing name by TWA when selling their system to travel agencies. Swiss International Air Lines and Brussels Airlines discontinued using PARS beginning of 2016. IranAir, the Iranian National Airline, discontinued using IBM-ACP/IPARS at the beginning of 2000 due to Year 2000 (Y2K) problem. CPARS (Compact Programmed Airlines Reservations) was used by smaller airlines (e.g. Icelandair). Among other limitations (compared to PARS) was a shorter booking horizon of 90 days.

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