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The way airlines price tickets is complicated – it all depends on a variety of factors including your origin, destination, dates, trip type, cabin, and much more. Airline revenue management and flight inventory will always be a mystery to me and every airline determines how they price their tickets and when they release lower (or higher) fares. A lot of this is controlled by the fare or booking class – which is assigned to every flight you book.

What is a Fare/Booking Class and Flight Inventory?

Every flight you book has their own inventory – so how many seats are sold, how many are left for sale, can the flight be oversold, etc. Airline revenue management controls the flight load and adds or removes additional inventory when they see fit.

Each flight has a series of fares and booking classes – you may have noticed that when you bought your tickets in the past, there was a letter designator next to your cabin class, for example, Economy Class (S) – in this case this flight is booked in the Economy cabin under fare/booking class “S”.

The higher the booking class is, the more expensive the ticket will be and the more miles you should theoretically earn. Every flight has their own inventory and therefore, booking classes, so you may notice that your other flights could be booked in other fare classes.

Example Flight Inventory and Fare/Booking Classes

Let’s take a look at a Lufthansa flight from New York JFK to Frankfurt and the available fares/booking classes on a specific flight. “Normal” people can’t usually access the view for the entire flight inventory, but travel agents can see most of the space available on a specific flight.

Lufthansa flight 401, JFK-FRA, Boeing 747-8i, on a random date in December has the following availability:

  • F5 A5 J9 C9 D9 Z9 P1 G9 E7 N0 Y9 B9 M9 U9 H1 Q0 V0 W0 S0 T0 L0 K0

Now all of that may look confusing – every flight has inventory and this is what it looks like. For example, “F5” means there are 5 seats left in First Class for sale or “Y9” means that there are at least 9 (if not more) seats left for sale in Economy Class.

Fare Types According to Booking Class

The more space in the cabin, the more fares there are – so a First Class cabin would have less availability and fares filed than Economy Class, as First Class has less seats. In the Lufthansa example, the corresponding booking classes to cabins are as follows:

  • First Class
    • F5 A5
  • Business Class
    • J9 C9 D9 Z9 P1
  • Premium Economy Class
    • G9 E7 N0
  • Economy Class
    • Y9 B9 M9 U9 H1 Q0 V0 W0 S0 T0 L0 K0

This does not follow the normal alphabet and instead, the above from left to right is an indication of highest to lowest fares. So the “F” fare is higher and more expensive than the “A” fare in First Class, for example. The highest fare/booking classes in each cabin also represent the amount of physical seats left. If it says “9” that means 9 or more.

In another example, we see that Premium Economy Class is listed as being available as “G9 E7 N0”:

  • “G” = highest booking class in Premium Economy Class and also indicates how many physical seats are left
  • “E” = mid-range fare in Premium Economy Class
  • “N” = lowest possible fare/booking class in Premium Economy Class

Therefore a ticket in “N” class will be much cheaper than a ticket in “G” class – in the live flight example, we can see that “N” class is already sold out, which means that Lufthansa is not selling any of the cheapest tickets in Premium Economy Class right now.

Economy Class has the most types of fares because the cabin is huge. In the classes listed above, we see that there is at least 9 (if not more) seats left in Economy Class (“Y9”) and that the cheapest tickets in Economy Class are already sold out (“K0”). In the case of Economy Class, each of those letters corresponds to a different fare, so:

  • Fully Flexible: Y, B
  • Semi Flexible: M, U, H
  • Semi Restricted: Q, V, W, S
  • Restricted: T, L, K

The more expensive the ticket is, the more flexible it is (free refunds and changes, for example) – while the more restricted the ticket is, the higher the costs are to change or cancel it, or those tickets may not allow cancelations or changes at all. Every airline has different rules.

All in All

It is important to understand the various different types of fares and booking classes available on a flight. If you see two flights on the same date from/to the same destinations and you notice that one flight is priced higher than the other, then chances are that some booking classes are no longer available.

While most people don’t need to understand all of this related to flight inventory, it can be helpful to know when you want to earn more miles or points for a flight – because the higher the booking class and fare, the more miles you will usually earn.

For example, a flight in Business Class “J” will earn more miles than Business Class “P”, because “J” class is more flexible and expensive than “P” class – therefore most frequent flyer programs would award you more miles for that fare class.

Travel Miles 101 has partnered with CardRatings for our coverage of credit card products. Travel Miles 101 and CardRatings may receive a commission from card issuers.