CRS — Central Reservation System

CRS — Central Reservation System

The CRS is the inventory engine at the heart of airline distribution. It maintains the single authoritative record of seat availability for every flight, ensuring consistency across all channels — direct, GDS and NDC.

Core Functions

A CRS manages: flight schedule and inventory setup, booking class (RBD) availability and yield management controls, real-time inventory updates across all distribution channels, waitlist management, group booking allocation and overbooking controls.

Relationship with PSS

In modern airline technology architecture, the CRS is the inventory and reservation module within the broader PSS. Some vendors treat CRS and PSS as synonymous; in larger airlines the CRS is a distinct subsystem within the PSS platform.

Historical Context

The first airline CRS systems — SABRE (American Airlines, 1960) and PARS (TWA) — were developed as internal airline tools. When airlines began allowing travel agents to access these systems directly, the CRS evolved into what became the modern GDS.

Inventory Control

Revenue management teams use the CRS to open and close booking classes (RBDs) in real time based on demand and load factor. This is the mechanism through which dynamic pricing and yield management are operationalised.