What is an airline reservation system?
An airline reservation system is the computer system that holds an airline's flights, availability and fares. This cheat sheet covers how to think about one and how airline systems connect to the people who sell tickets. The detail is further down.
How to think about it
- It's the airline's own system. US rules refer to the flights published in "the carrier's Computer Reservation System at the time of the ticket sale."
- Multi-airline systems serve travel sellers. A computerized reservation system, or CRS, holds schedules, availability and fares for more than one airline, for subscribers who book on behalf of clients.
- What's listed decides what counts. In US airline reporting, a flight not operated but still listed in the carrier's system within seven calendar days of departure is a cancelled flight. One dropped more than seven calendar days before departure is a discontinued flight.
- Airlines pay the system vendors. The booking fee is the price airlines pay system vendors for the services a CRS provides.
How it works on Engine
Engine's flight content comes through both GDS and NDC connections. When you book a flight, you filter and sort by schedule, stops, airline, cabin, duration and price, then review the fare details, including included baggage, before you pay.
Questions
What's the difference between an airline reservation system and a GDS?
An airline's own system holds that carrier's flights. A global distribution system is a computerized network that connects travel providers with travel agents and distributes inventory and rates in real time.
What is a CRS?
A computerized reservation system holds schedules, availability and fares for more than one airline, with or without the ability to make reservations or issue tickets, and is made available to subscribers who book on behalf of clients.
What are examples of reservation systems?
Amadeus is a major global travel reservation system used by hotels and travel agencies.
How does NDC relate to reservation systems?
NDC is an IATA data standard, not a system. It improves communication between airlines and travel agents, letting sellers shop, order, pay for and service airline products through an API.
Sources
- European Union (via legislation.gov.uk), Regulation (EC) No 80/2009 of the European Parliament and of the Council of 14 January 2009 on a Code of Conduct for computerised reservation systems, accessed November 2, 2026.
- US Department of Transportation (eCFR), 14 CFR Part 260: Refunds for Airline Fare and Ancillary Service Fees, accessed November 2, 2026.
- US Department of Transportation (eCFR), 14 CFR 234.2: Definitions (Airline Service Quality Performance Reports), accessed November 2, 2026.
- Engine, Hotel abbreviations list: Guide to hospitality terms, accessed November 2, 2026.
- Engine, Hotel reservation systems: A guide for hotel managers, accessed November 2, 2026.
- IATA, Distribution with Offers and Orders (NDC) Fact Sheet, accessed November 2, 2026.
- Engine, Engine vs. Traditional TMCs, accessed November 2, 2026.
- Engine, Business Flight Booking With Engine, accessed November 2, 2026.