This document describes an airline reservation system that contains flight schedules, fares, passenger reservations, and tickets. It has three modules: registration, administration, and passenger. The registration module allows passengers to create accounts. The administration module allows updating flight information and viewing passenger lists. The passenger module allows viewing flight details, booking tickets, and sending feedback. It proposes implementing this system using a three-tier architecture with presentation, business logic, and data tiers. UML diagrams including use case, class, and sequence diagrams are described to design the system.