Airline Fare School # 3 – The Basics, part 3

In AFS # 1, and 2, you learned about fare displays, rules, and routings. These are the underpinnings of the airline fare system but of course they’re purely theoretical until applied to a booked itinerary.

Let’s take that next step.

We’ll stick with the example we’ve used so far: the $99 one-way fare from Sacramento to Chicago on Unted Airlines on 13 October. The fare basis code for this fare is LA14ON8.

A fare basis, as I mentioned before, is the unique code that applies to a fare and the rule that governs it. Most airlines apply a kind of logic to how they name these but it is not consistent from airline to airline, with the exception of the first letter of the fare basis. We’ll dissect LA14ON8 for kicks.

– L the first letter is nearly always the same as the inventory that must be sold on the flight
– A14 means advance purchase 14 days
– O probably means “off-peak” because the fare is only valid Tue/Wed/Sat
– N means non-refundable
– 8 is probably arbitrary

Naming the fare basis with some semblance of logic is useful for airline employees or travel agents as it gives them an up-to-8 character snapshot of the rules of the fare.

Let’s now focus only on the L part of the fare basis. Using complex models of “yield management”, the airlines slice and dice airline seat inventory into many different categories often called “buckets”. Only a few “buckets” are used for full-fares (F for first class, C for business class, Y for coach) but the vast majority are used for selling the plethora of discount coach fares. (Except for the use of Y for full fare coach, there is no consistency between the airlines as to the assignment of letters for inventory codes. One airline might use O to sell its mostly deeply discounted fares. another airline might use G, and another might use T, etc.)

In its simplest form, the cheaper the fare, the less inventory is allotted to the bucket in which that fare must be sold.

Here’s what basic availability looks like for a travel agent or airline employee for United between Sacramento (SMF) and Chicago O’Hare (ORD) on 13 October:

594-AFS 3 - avail 1.jpg

I suspect that most of what you see above will be self-explanatory. (You are looking at where the user-friendly displays of flight choices on the internet derive their data.)

Using line 1 as an example here’s what each column represents:
– the line number if you wish to sell the flight
– the two character airline code
– the flight number
– the various inventory codes and how many seats (up to 9) that are available
– + sign at the end means there are more inventory codes to view
– the cities (SMFORD); connections look slightly different, such as the 6:00 a.m. schedule via DEN or the 6:00 a.m. schedule via LAX attest
– the departure and arrival times of each flight
– the aircraft equipment used (a Boeing 757-200 on line 1)
– the percentage of time in the past year a flight has been on-time (the 8 on line 1 means that the flight has been within 15 minutes of its scheduled arrival between 80 and 89% of the time)

Now let’s look at the inventory codes from left to right.

In this instance it begins with an F for a full fare first class seat. (If it were a schedule starting from Chico the first inventory shown would be Y because there isn’t first class service on the small aircraft that operate to SFO.)

From that point on all of the visible inventory codes are for different “flavors” of coach starting with Y (full fare coach) , then B, M, E, U, H, Q, V and W. And the + signs means there are more.

Really? More? Yes, more.

Now remember, we need L for that $99 fare so we’ll need to look at the expanded availability just for that flight to see if there’s an L seat.

595-AFS 3 - avail 2.jpg

Now for this flight, we see everything. In addition to the other inventories we now see S, T, K, L, and G for coach travel. (For United P and A are used for discounted first class fares.)


Believe it or not, this still isn’t everything because airlines have even more inventory codes for stuff like mileage award tickets, employee travel, and so on.

OK, so what number follows L? Yes, a big fat ZERO. No L seats available on this flight so you can’t get the $99 fare.

So you go back to your original availability get the complete availability display for the second nonstop flight at 1:32 p.m.

596-AFS 3 - avail 3.jpg

Guess what, L is available. (Notice that this flight is more of a slacker, showing a 7 for its on-time reliability meaning 70-79% on time.)

OK, we sell a seat on that flight and now we want to see what the total price will be.

Here’s a view of the sold flight segment with the price breakdown:

597-AFS 3 - seg fare.jpg

The first line is the sold flight segment. SS1 means sold-1. The rest on that line is pretty obvious.

The second line is the fare calculation showing the cities, the carrier, the base fare (before tax) and fare basis.

The third line shows the complete breakdown with tax and fees.

92.09 is the base fare before tax (this is what the airline actually keeps)
2.50 AY is the September 11 flight segment security fee
6.91 US is the 7.5% Federal Transportation Tax    ($92.09 + $6.91 = $99 in the fare display)
4.50 XF is the Passenger Facility Charge for Sacramento airport
3.60 ZP is the Flight Segment Tax

Add those all up and you get $109.60, the total price you would pay not including optional extras that used to be free including meals, checked baggage fees, etc.

Here’s how exactly the same thing would look to you using

598-AFS3 - united-dot-com SMFDEN only.jpg

Note: See the link in to “Fare rules”? This will take you to a display of the rules that an airline agent or travel agent would see, and like what we looked at in AFS # 1.

If you’re thinking as a reader, OK, I’ve gone through three chapters of Airline Fare School now to learn what I could have found out at or Expedia just by looking for a one-way fare from Sacramento to Chicago on 13 October, then you’re missing the point.

What’s different is that now you have a basic understanding of what is going on ‘under the hood” when you use an airline or on-line travel agency website (or call an airline or travel agency). Fares, rules, routings, and the availability of inventory to match are what make possible the array of flights you can choose from on-line or over the phone.

And knowing that there may be things in those rules that make more interesting trips conceivable is where we’re headed. Knowing what might be possible may change what you ask for in the first place.

Your newly found knowledge will be useful as we move on to our next installment in Airline Fare School: # 4 – One ways and round-trips.

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