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Airline Reservations Systems - Introduction

Introduction

Airlines have, among others, two major problems:
they sell a commodity — seats — which
are highly perishable and can be very
expensive;
and they face competition, not only from other
airlines, but from high-speed trains and other modes of transport.

Why is an airline seat perishable? Because the aeroplane door must
shut, and if the seat is empty its income is lost for ever.
And it's expensive, clearly, because the lost income could be
thousands of pounds for each empty seat¹.

Reservations Systems are one of the tools airlines use to help to
solve these problems.

Solving the Problems

Inside its reservations system, a typical airline keeps track of two
inventories of things that are "precious": seat
inventory and passenger inventory.

Seat inventory is a count of all the seats on every flight over the
dates handled by the system (usually from yesterday for 51 weeks);
counts are kept of seats booked and of seats available in every class
on every flight.

Passenger inventory is a fairly large amount of data, kept for each
passenger with any kind of booking on the airline's flights.
It includes passengers who have booked and then cancelled, and waitlisted passengers who may have no real booking but are for some reason waiting for confirmation of a seat on a specially full flight.

What?