Go ahead and flame me. This question probably has already been answered. But I notice that for class availability Fn, Ym, m is always >/= n. Does this mean that DL will sell a Y seat with the expectation that, if necessary, they can bump that person into F? So a class availability of F3 Y3 would mean there are three seats available for sale, not six, right?

My understanding that would be a total of 3 seats in inventory.

I don't think so.

You can see something like Y0 F9. So no, Y does not include F.

No. This means there are 3 F seats available for sale and 3 Y spaces (notice I didnt say seats) for sale. Y is spaces because they will oversell Y at the full Y fare rate.

That's the point. I don't think I have seen that. Of course, the order would be F9 Y0. Can you point out an example of that? I think the reason not is that if they have F2 Y2, some people will by Y rather than F for company policy reasons, even though F is generally not much more than Y.

DL 4167 on 5 Dec: F7 Y5

Fair enough, but same question. Are there 7 seats for sale or 12?

AA 3867 on Dec 1 F5 A4 P4 Y0 B0 H0 K0 M0 L0 W0 V0 G0 S0 N0 Q0 O0

There are 5 seats in coach and 7 in F for a total of 12 seats for sale on the plane.

That is incorrect.

DL is overselling Y, and part of the logic for this is based on upgrades and op-ups.

If somebody bought all 7 F seats, then they now know Y will not get the upgrades so they will reduce Y inventory.

It is also possible there are more than 7 F seats available. It would not stun me if JFK/LAX held a few back in order to score the very expensive last second F (BE) seats.

It's a complicated process, and nobody outside DL will know exactly how it works (though I am certain many know the general concepts).

I don't think there is single simple answer. It is certainly possible to have a flight sitting at F3 Y4, purchase an F seat and see it drop to F2 Y4 - i.e. the Y number does not drop. I also often see flights that are something like F6 Y0 - particularly in heavy holiday traffic.

Good points - the inventory is so dynamic it is virtually impossible to know exactly how many seats are available after any given query. It is also important to think about the authorized vs actual numbers to which we don't have access. That is the total number of seats authorized for sale vs the actual seats on the plane - those can be very different numbers.

Using the above example there are likely fewer than 12 seats available on the plane but they are willing to sell at least 5 reservations in Y and have a total of 7 seats in F. It very will could be that the current available numbers are F7 Y0 but they are willing to oversell coach by an additional 5 reservations (Y could already be over by, say X so you would have a total available on the aircraft of F-(X+5)).

Whenever you see F# Y#, those are the number of seats authorized for purchase. For example, Y6 doesn't mean there are 6 actual seats remaining in coach. It means that we are willing to sell 6 more. Y9 is the highest it goes, so it could mean we are willing to sell 9 more seats or it could be 200 more seats. Also, the coach cabin could already be oversold ("sold above actual capacity"), but you have no way of knowing that.

*Cue the mysterious black box known as Revenue Management.*

THIS is the correct answer. If one were to look in the travel agents' handbook it would describe the number (as in Y#) as "the number of seats the airline is willing to sell at that fare class" or "the number of seats available to sell in the fare class" ... as above. That's why the formal name of that information is availability.

And first class (F, A, et al) availability is almost always completely independent of coach (Y, B, M et al) availability (there are some arcane company-dependent exceptions). So it is indeed possible to have almost any combination of #s (providing #<9).