How the schedule, fares and inventory reach a customer, and how we check them
This page is for pricing and revenue management specialists. It shows the systems and messages from the schedule to the sale, sets out the six checks of our review, and lets you price a flight yourself.
Schedule, fares and inventory travel separately, and meet only when a customer asks for a price
The reservation system holds the master schedule and the inventory. Fares go out separately through ATPCO. Each channel combines the three when someone shops: a GDS from the filed data, your own offer engine for the website and NDC.
| No. | Link, and what travels on it | What we set there |
|---|---|---|
| 1 | Network planning to the reservation systemThe seasonal schedule as an IATA SSIM file, then SSM and ASM messages for each change. The reservation system holds the master schedule and builds each flight’s inventory from it. | Cabins and booking classes for each aircraft, how far ahead flights go on sale, and how schedule changes move existing bookings. |
| 2 | Network planning to OAG, Cirium and the GDSsThe same schedule. The aggregators pass it on to the GDSs and other users, and some airlines also send it to the GDSs directly. | Changes sent in time, so agents never sell a flight that has moved, and codeshare flights shown correctly. |
| 3 | Pricing to ATPCOFares by market with their rules, footnotes and routings, fare brands (Record S8) and optional services such as bags and seats (Records S5 and S7). | Price points and their conditions in each market, the brands, the extras, and which fares are private. |
| 4 | ATPCO to the GDSs and the airline’s own systemsThe filed fares, distributed at scheduled times. A fare meets a flight only through its booking code; fares are not filed per flight. | Which fares each channel receives, and the branded-fare display in each GDS. |
| 5 | Revenue management and the inventoryControls into the inventory, usually each night: booking limits by class, bid prices, the overbooking level, and point-of-sale and journey rules. Bookings, cancellations and no-shows come back. | Nesting, the control method, overbooking, origin and destination and point-of-sale rules, married segments, and when analysts override. |
| 6 | Inventory and the GDSsAvailability status messages (AVS and NAVS), which keep a copy in each GDS that shows at most nine seats, and live requests from the GDS to the inventory for airlines that take part, with the whole journey for origin and destination control. | The participation level in each GDS, and whether journey data reaches the inventory. |
| 7 | GDSs to reservationsBookings by travel agents and online agencies. The GDS prices them from the filed fares and keeps its own copy of each booking. | Rules against split married segments, duplicate bookings and bookings held without a sale. |
| 8 | Offer engine to NDC and your own channelsOffers built by the airline: price, brand and extras, including continuous prices, for NDC aggregators, GDS NDC connections, the website and the app. | The NDC set-up, which aggregators to connect, and which offers each channel shows. |
| 9 | Reservations and partner airlinesAvailability and bookings for interline and codeshare journeys, priced as through fares from filed fares. | Interline and codeshare agreements, class mapping and prorates. |
| 10 | Ticketing to settlementE-tickets and EMDs, reported and paid through BSP or ARC. Partner airlines bill each other after travel through the IATA Clearing House. | BSP and ARC participation, and EMDs for paid extras. |
| 11 | Departure control to revenue accounting and revenue managementWhat flew and who did not show, back into the forecast within days and into the schedule for the same season a year later. | How fast flown data reaches the forecast. |
Our review asks six questions, from the fares you file to the revenue you earn
We check the fares, systems, rules and channels behind every price. Each gap we find gets a revenue figure from your own data. Each fix ends with something your team runs without us.
Each price point is a fare with its own conditions, for a different kind of traveller. We build a full ladder of price points on a logarithmic scale, so every step is the same percentage. A tailored one-way analysis makes sure the offer does not undercut your return fares.
What you get
- Price points in use, by route and season
- A logarithmic ladder of price points
- A one-way analysis for your routes
Fare brands can share a booking class, because the fare basis tells them apart. One class can sell a fare without a bag, a fare with a bag and a fare with free changes. We file brands and optional services so travel agents can see and sell them, and ancillary revenue grows in every channel.
What you get
- Fare brands with rules and fare basis codes
- The price step from each brand to the next
- Extras by route type: bags, seats, upgrades
Which price points are open should follow bookings, a forecast and what the seat is worth to your whole network. We check how your system forecasts, how it controls availability by journey and point of sale, including married segments and O&D control, and who overrides it.
What you get
- Forecast accuracy by route
- Revenue earned or lost by manual overrides
- Availability control by journey and point of sale
A filed fare is a fixed step. Continuous pricing lets the price sit anywhere between steps, and dynamic pricing moves it as bookings, demand and rival fares change. We check what your systems can do today and what they need next.
What you get
- What your systems can and cannot do
- Rules for how far and how fast a price may move
- A plan from filed fares to continuous prices
A price earns nothing if the passenger cannot see it. Your website, NDC and GDS travel agents can show different fares for the same seat, and interline and codeshare partners can sell your network worldwide. We compare what each one shows and what it costs you per booking.
What you get
- The fares each channel shows for one seat
- Reach through interline and codeshare partners
- Net cost per booking by channel and market
Every change has to show its result against flights that did not change. We switch between old and new pricing on comparable flights, so season, rivals and schedule affect both. Your finance team agrees the method first.
What you get
- A test design your finance team signs off
- Results by route, with control flights
- A routine to keep testing after we leave
The fare structure decides how many prices a flight can sell
Five facts set the limits of any fare structure. We work through each of them with your pricing team.
- Classes free for pricesNot every booking class is free for revenue price points. Each cabin needs its own classes, F, J, W and Y keep their usual meanings for partners and GDS defaults, and airlines keep classes for awards, upgrades, groups, staff and partner bookings. An airline with two cabins and no award programme can sell more price points in economy than one with four cabins.
- The ladderOn a logarithmic scale every step is the same percentage. From USD 500 to USD 3,500, 26 price points sit about 8% apart, each 1.081 times the one below it, and six price points sit about 48% apart.
- Brands in one classBrands can share a booking class through the fare basis, with two limits. A GDS prices the cheapest fare in the booked class unless the agent asks for a brand, and inventory control works per class, so brands in one class open and close together. Air Canada has shared classes between brands since September 2017 and asks agents to use brand codes.
- Dual inventoryA fare can require a second booking class to be open, such as a fare in C that needs M to be available. ATPCO lists this validation as working in all channels. Two-character classes such as YN exist only inside airline systems.
- One-way faresPriced on their own, two one-way fares can cost less than the return they replace. We set one-way levels route by route, for each brand and season, so the return stays the better buy.
Try it: price one flight and see what each setup misses
One flight with 70 seats and 60 days of bookings. Choose how many price points are on sale, which fare brands each one sells and whether prices respond to bookings. A review does this for every flight in your network, on your own data.
The simulator loads as you reach it and needs JavaScript.
A result counts only when control flights show it
- ComparisonWe switch between old and new pricing on comparable flights, so season, rivals and schedule affect both groups the same way.
- Sign-offYour finance team agrees the method before the first change, and the result goes into their reporting.
- LengthA test runs for the 8 to 12 weeks of the set-up step, on a small set of routes.
- Flat resultsIf the numbers do not move, you will see that too. Seven questions show how to read any uplift figure, including ours.
The loop and the checks rest on published sources
We checked each step of the loop against published documents in November 2026. These are the main ones.
- ATPCO, updates on booking classes, September 2018: two-character classes and dual validation.
- ATPCO, Branded Fares white paper, 2023.
- Air Canada, Branded Fares GDS guide, February 2018: brands that share booking classes.
- IATA, Airline retailing: an industry vision for offers and orders, October 2021.
- ACI, IATA and WWACG, Worldwide Airport Slot Guidelines, edition 4: the 80% use rule.
- South Africa, Airport Slot Coordination Regulations.
- ICAO, Facilitation Manual (Doc 9957), chapter 9: passenger records and government data.
- IATA, Billing and Settlement Plan, and the IATA Clearing House, July 2024.
- US Government Accountability Office, GAO-20-191: overbooking and no-shows.
- Peter Belobaba, Airline management, MIT 16.75J, lecture 18: forecasts from booking history.