Airline Schedules Data: An Insider’s Guide

Aviation is a complex business encompassing hi-tech aircraft, engineering, scientific principles, and many global rules and regulations, which not only regulate the industry, but also ensure the safety of all passengers and cargo consignments flying around the world.

Aviation is also a very innovative sector, with real pioneers who continually create new airlines, routes and operational strategies, and highly skilled professionals focused on delivering the best possible services. And yet, without a few columns of data that are communicated effectively, the industry would come to a grinding halt. 

Welcome to the world of Flight Schedules!

What is an Airline Schedule? 

We all recognize the concept of an airline schedule.  It is the promise of a flight from point A to point B on a particular day and at a specific time, with an incredible level of accuracy about how long that flight will take and a plethora of data points surrounding that core piece of data. 

Airline schedules are in many cases regulated, requiring slots and permission to operate between two airports or countries - issues we touch upon in other recent blogs.


What data makes up a flight schedule?

Several years ago, industry regulators in partnership with various user groups introduced a standard data format to engance operational efficiency. This ensures consistency of data around the world for all users and systems. The SSIM, and SSM (Standard Scheduled Message), have standardized the data allowing its rapid movement between airlines, distributors, GDSs and all interested parties, no matter where they are in the world. This has ensured that the latest information is available to travelers when booking flights. It is this freshness of data that is becoming increasingly vital to airlines and passengers, especially when the codeshare dimension is added to the equation.

This data not only regulates the format in which schedules are published, but also provides the formats and codes in which data can be presented, making these codes well recognized. For instance, most people recognize a “77W” or a “351” or even a “32Q” as specific aircraft types, in these cases a Boeing 777, a A350-1000 and finally a A320 NEO. And JFK is instantly recognizable as New York John F Kennedy and LHR is London Heathrow, although sometimes airports with very similar codes can cause confusion; every year someone books a flight to somewhere obscure by misreading the airport code. Apart from those obvious codes, there are many more different pieces of data that tell “the story” of a specific flight.

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Of course, every airline has its own operating code. Sometimes it’s the actual operating carrier, and on many occasions, it may be the codeshare carriers - but carriers such as SQ, AF and EK are known to most travelers. Some codes such as 6E (IndiGo Airlines) have to use a number as part of their code since so many airlines hold two-letter prefixes, but it certainly doesn’t stop them from growing!

Anyone conducting analysis and benchmarking on flight schedules needs to understand the meaning of the codes for their analysis to be accurate. This is where reference data comes in. Industry codes provide universal abbreviations to facilitate travel and enable a common language to be interpreted and understood across systems all over the world. They are typically 1, 2, 3, or 4-character combinations that uniquely identify locations, equipment, carriers, and times to standardize international flight operations.

For each flight, airlines provide information on the number of seats that they are operating on that flight. In many cases that includes First (F), Business (C) and Economy (Y) - and how we all wish to geta flight ticket with “F” instead of “Y”. Airlines also must file what type of flight they are operating, so a flight with a “J” prefix is a normal service while a flight with a “P” would be a positioning service and some may remember the “S” code used for shuttle services many years ago. 

When incorporating additional data points such as smoking/non-smoking (it’s hard to believe this is still a field, and most airlines have non-smoking as their default), the meal service offered, availability of in-flight entertainment, and the terminals for departure and arrival, suddenly there is a long line of data that forms an important part of an airline schedule, and it all must be provided in a common format.

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Schedules Volatility and its Impact 

In today’s dynamic world, airlines are changing their schedules daily and in times of geo-political events or pandemics the frequency of change can almost become hourly! Historically, airlines changed their schedules twice a year operating winter and summer seasons that began and ended with the clock changes in late March and October.

A schedule change that is not updated quickly enough can lead to passengers booking flights that no longer exist and creates unnecessary, non-revenue producing work for airlines. Equally, airlines want new flights available for sale as quickly as possible so putting their flights on sale is vital.

Deregulation, increased competition and a more effective alignment of schedules to demand have resulted in airlines changing their schedules nearly every week. They may add new routes, adjust frequency or merely make a thirty-minute time change and OAG’s database must accommodate all those changes instantaneously. And as the airline industry has evolved and changed its way of operating, the technology that OAG uses to support the constant changing of airline schedules has always been one stop ahead of industry requirements. As we receive so many schedule changes throughout the day, we can pass these on in near real-time, to ensure the ecosystem stays in the know on what is happening on the ground and in the skies.

To give an idea of the scale and size of the schedules data footprint OAG works with, we can have anywhere between 55-60 million flights on our database that are departing within the next two years. Couple that with lots of daily changes, additions and withdrawals, that’s a lot of data!

Take a sneak peek at some of our schedule statistics from May 2024:

  • 120,000,000 total changes
  • 12,400,000 flights added
  • 7,400,000 flights withdrawn
  • 11,700,000 departure time changes 

How often do Airlines publish schedules and how does it vary?

The bigger the airline network, the higher the frequency of the updates. Airlines often release a bulk of schedules at a time, for example, their summer or winter flight schedule. Most airlines roll forward their schedules and place them on sale approximately 330 days before travel, although some LCCs (low-cost carriers) stretch that out further as the cash flow benefit makes it worthwhile. Those schedules that are rolled forward are always subject to change and the twice-yearly IATA Slot Conference has a bearing on the final schedules, especially if additional slots become available at some airports so there are always refinements being made and schedule changes can occur at any time up to 48 hours prior to departure. 

Network Planning and Revenue Management teams keep a close eye on big events such as the World Cup or the Olympics and update their schedule accordingly to take advantage of increased demand. By making a minor equipment change, the airline can have additional seats to sell which results in increased revenue. 

Any change, even minor, needs to be communicated promptly to the rest of the travel ecosystem to ensure operations and passengers are kept in the know. A schedule change can consist of anything from a departure time change to an equipment change. 

Where do Airlines send their schedules and why? 

To ensure that every airline provides the data in the same format and structure, IATA (International Air Transport Association) along with airlines and distributors developed a common format widely known as a SSIM (Standard Schedules Information Manual) file which airlines must adhere to when submitting their schedules to OAG. 

The world’s commercial airlines, whatever their size, have been sending OAG their flight schedules for over 90 years, and use our complimentary distribution and data management services and wider ecosystem reach to drive ticket sales and support on the day travel experience. OAG then distributes the schedule to all industry stakeholders such as Global Distribution Systems, OTAs, Airport Service Providers, Airports, Booking and Reservation systems and many more.

If you think about how many flights an Airline operates a day (on the 10th of June 2024, British Airways operated over 900 flights), that results in a lot of data and complexities around distribution to the travel ecosystem.

That’s why airlines choose OAG as their distribution partner, as they have access to a team of schedules data experts and data quality checks to ensure that the schedules that are distributed are of the highest quality. There may sometimes be anomalies with codeshares or equipment types, which OAG will verify and amend (if necessary) before releasing to the wider industry. 

OAG’s systems can handle hundreds of airline feeds, monitoring the process and checking their accuracy and ensuring coverage and completeness. Our systems handle hundreds of thousands of schedule changes daily from 900+ airlines, which are then distributed efficiently to all stakeholders.

A Library of Key Data Points

 OAG also maintains a highly valuable database that supports the airline schedules data that is received from airlines.  This reference data is vital and contain all sorts of important reference data points such as location, equipment codes DST and time zones without which there is the potential for serious errors and confusion.   For instance, we hold the latitude and longitude points of every airport in the world and, incredibly, on occasion they do change, especially when a new airport terminal or runway is completed. This database also includes terminal data, and DST and UTC times and which airlines, and sometimes specific flight numbers, operate from which terminal when there are multiple facilities, such as London Heathrow or New York JFK.

However, perhaps the most important piece of data is around connecting times. For many travelers, reaching their final destination requires a change of plane and making a connection somewhere. Keeping a record of the most recent “published connecting” times is crucial for airlines and airports and can be very different for each airline at the same airport.  A Minimum Connection Time is the amount of transfer time, agreed in advance between airlines and airport authorities, that is considered sufficient for a passenger to make a connection between an arriving flight and a departing flight. Carriers submit updates to OAG and these are then used by global distribution systems and connection builders.

Taking Chicago O’Hare Airport as an example, the Minimum Connection Time (MCT) from an international to domestic flight can vary between American Airlines and United Airlines, the two largest carriers at the airport, whilst there will also be a generic airport MCT published. These MCTs are then used to calculate all the potential connections that are placed on sale for airlines operating around the world and with every minute being crucial in the world of MCTs airlines are regularly changing their specific connecting times to have the best possible connections on sale. 

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When analyzing flight schedules, a fluency in schedules terms and abbreviations may come in handy:

The Evolution of Schedules Data and What’s Next?

OAG is the global leader of schedules aggregation. This has been built on a long history of receiving, verifying and distributing data directly from airlines and sending onwards to Global Distribution Systems and other customers. For all but the very biggest airlines supplying direct feeds of data to all distributors is a thankless and expensive task and runs the risk of a data file being missed with schedules subsequently incorrectly sold. OAG’s pivotal role overcomes that challenge for airlines, and for our customers they know that we are sending them the freshest data set available every day of the year.

The evolution of data since our first published print timetables in 1929 has been incredible. Where once airlines changed their schedules twice a year it’s now daily. Rather than thousands of flights a year we are now handling millions of data records each week and with the creation of new distribution capabilities (NDC) in recent years more and more work is going on behind the scenes to ensure that our data continues to be the most accurate and freshest available as we support the aviation industry and make travel as easy as possible for everyone.