What CRS means
The term CRS dates from the first airline computer systems. American Airlines and IBM installed the first Sabre reservation system in 1960 on two IBM 7090 computers, completed a nationwide network in 1964 and put a terminal into a travel agency for the first time in 1976. Before that, bookings were tracked on paper and by telephone.
In airline distribution the phrase now covers three related things. An airline CRS is the reservation module of a carrier's own passenger service system, where its bookings and seat inventory live. A multi-airline CRS shows schedules, availability and fares for many carriers to travel agents; these systems grew into today's GDSs. A hotel CRS (central reservation system) manages a property's or a chain's room inventory and rates and pushes them to every sales channel.
Regulators still use the older wording. The EU Code of Conduct, Regulation (EC) No 80/2009, defines a computerised reservation system as a system holding schedules, availability and fares for more than one air carrier, with or without booking and ticketing facilities. Under that definition a GDS is a CRS, while a single airline's internal system is not.
Because the same three letters mean different things to an airline, a GDS vendor and a hotelier, it helps to confirm which system someone means before comparing products or prices.
How CRS works
Whether it serves an airline, a travel agency or a hotel, a CRS follows the same basic cycle from inventory to confirmed booking.
- Load inventorySchedules, booking classes, room types and rates are loaded into the system and kept current as the supplier changes them.
- Answer availability requestsA user or connected channel asks what can be sold for a date and route or stay, and the CRS returns open inventory and prices.
- Create the bookingSelling a seat or room decrements inventory and creates a booking record, such as a PNR for air travel.
- Confirm and fulfilPayment, ticketing or a hotel confirmation number completes the sale and is stored against the booking.
- Synchronise with other systemsMessages keep other systems aligned, for example a GDS and an airline exchanging booking updates, or a hotel CRS updating its connected channels.
CRS in practice
Airline and GDS (illustrative): an agent in Dubai books a European flight in a GDS. The GDS sends a sell request to the airline's own reservation system, which confirms the seat. The booking now exists in both systems, often with two different record locators, one for the agency's GDS PNR and one for the airline's record.
Hotel group (illustrative): a 40-property chain sets a weekend rate once in its central reservation system. The CRS sends that rate to the chain's website, to GDS hotel listings and, through a channel manager, to online travel agencies, while each hotel's PMS handles check-in and billing on the day.
Regulation: in the EU, Regulation (EC) No 80/2009 sets conduct rules for system vendors, the companies that operate or market a CRS, and for the carriers that participate in them.
Who uses it
Advantages and limitations
Advantages
- A single, authoritative store of inventory prevents the same seat or room being sold twice.
- Electronic booking records make changes, cancellations and reporting far faster than manual methods.
- Standard messaging lets one booking flow between suppliers, agencies and intermediaries without re-keying.
- Hotels can update a rate once and have it reflected across all connected channels.
Limitations
- The term is ambiguous, so contracts and product comparisons can go wrong if airline CRS, GDS and hotel CRS are confused.
- Older airline and GDS reservation systems rely on legacy formats that are harder to integrate with modern web APIs.
- Keeping several systems in sync creates mismatches, such as a booking cancelled in one system but still active in another.
Frequently asked questions about CRS
Is a CRS the same as a GDS?
Not exactly. Every GDS is a multi-airline computer reservation system, and EU law still calls GDSs CRSs. But an airline's own reservation system and a hotel's central reservation system are also called CRSs, and neither of those is a GDS. A GDS sits between many suppliers and many travel agencies.
What is the difference between a hotel CRS and a PMS?
A hotel CRS manages what the outside world can book: room inventory, rates and availability across websites, GDSs and online travel agencies. A property management system (PMS) runs the hotel itself, covering check-in, room assignment, housekeeping and guest billing. Many hotels connect the two so that bookings flow automatically from the CRS into the PMS.
What was the first computer reservation system?
Sabre, developed by American Airlines with IBM, is generally cited as the first. Its first system was installed in 1960 on two IBM 7090 computers, the full network was completed in 1964, and it was installed in a travel agency for the first time in 1976. AMR spun Sabre off as an independent company in 2000.
Why do airline bookings have two record locators?
When an agency books through a GDS, the booking is stored in the GDS and in the airline's own reservation system. Each system issues its own reference, so the agency's PNR locator and the airline's locator usually differ. Both point to the same reservation, and the airline's reference is the one used for online check-in on the carrier's website.
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