I apologize in advance if this has been discussed before but wanted to see if someone could clarify a question for me on fare class availability. I know that during the first part of a week (usually Tues) fares are normally updated in the system. Towards the end of the week, does Delta tend to "block" certain fare buckets in the hopes of getting people to buy a higher fare ticket and then "unblock" the lower class fares the following week? The reason I'm asking is that I priced a ticket earlier this week and checked again today and the fare was almost $250 higher. Thinking that maybe the fare classes sold out, I went to Expertflyer to check the availability on the flights and came up with the following:

T0 U0 L0 K0 Q0 H0 M9 B9 Y9 A9 P9 F9

Checking the DL website seems to confirm that the lowest fare available is an M fare. What doesn't seem to make sense to me is that when I check the seat map, there are almost 100 unassigned seats remaining on the aircraft. I understand that sometimes the seatmaps aren't updated in a timely manner however it seems like there is a large discrepancy with what shows as availabile in Expertflyer versus the seat map.

I'm going to check again for the same flights next week to see if any other class availability opens up but if anyone could shed some light on why there could be zero availability in the lower classes but the seat map shows a wide open flight I'd apprecate it. Thanks and safe travels!

It all depends on the route and how their internal systems are allocating inventory and spreading demand. I've seen fare bucket availability vary to extremes just within several hours... T fares would show up and then 2 hours later it was gone and only H was available, then the next day it was back to L. There really is no logical explanation without knowing the inner workings of their revenue control system and inventory system... thats just how it is. Fares can vary a lot during the day and week.

Also would have to do with the fare rules. Some fares require and advanced purchase of X amount of days. Depending on how long it is till the flight, the fare may no longer be available based on that.

How far out is this flight? If it's for 3, 4, 5, 6+ months out and M fare is all that's available, I'd sit on it as DL does not fill entire planes on M fares. If it's for next week, your options are far more limited.

Agreed. For some reason Delta likes to price high when booking far in advance (like their award calendar), but then they release much lower fares about 4-6 weeks before departure. Not on all routes, but many.

A few thoughts on this:

In fact, fares are updated in the system about 18 times a week - three times a day during the week, twice on Saturday, and once on Sunday (I think that's still true). Price increases tend to come out later in the week, while sales tend to come out earlier.

Buckets open and close based on a formula which looks at: (a) current bookings; (b) historical booking trends; (c) bookings on other O&Ds utilizing that segment; and (d) individual analyst adjustments. Based on my experience buying tickets on DL over the last year, my guess is that their YM strategy is to avoid opening up U and T until it's clear a flight is not doing well on bookings. Seeing it zeroed out up to M tells me that the flight is doing better than expected at this point in the booking curve.

The number of unsold seats doesn't necessarily translate to the need to open up lower booking classes. For example, suppose you had historical data showing the following booking curve for a 100 seat aircraft on AAA-BBB

330-90 days: 10 (90)
90-60 days: 10 (80)
60-30 days: 10 (70)
30-21 days: 30 (40)
21-14 days: 10 (30)
14-7 days: 10 (20)
7-3 days: 15 (5)
3-0 days: 5 (0)

Now if you were 100 days out, and had already sold 25 seats, you'd definitely want to ratchet things down a bit - you are well ahead of the booking curve, even though the flight is only 25% full. Then it gets even more complicated, as sometimes seats are held for connecting itineraries (MOB-ATL-LHR) and not open on the local (MOB-ATL) - this is because the airline wants to sell the ATL-LHR segment as well.

So long story short, the number of open seats doesn't dictate the fare class availability.

I think that's a good plan. The odds of M closing before you buy at this point are lower than the odds of something below it opening up. I tend to keep an eye on flights when they're only open in L, and then as soon as I see something in U or T open up I grab it. So far it's worked well.

^^^ If all this is accurate, then this is a great summary of how Delta releases its fare classes!

Thanks for all of the responses. I guess I should have grabbed the flight when it was cheaper but I had some other arrangements to finalize before I could consider booking it. I'm just going to wait and see what happens over the next few days to see if the price comes back down.

For what it's worth, this was for a flight about 5 weeks out (7/19) so I don't think I was too early or too late. The good thing for me is that this was a "nice to take" flight and not required. I guess I'll just shop around for other places to visit and see if I can find something a little more economical.

Thanks again for the responses!

Fares do change during the day - there is nothing more fun than having an indecisive and cheap boss who asks for a travel estimate at 9 AM and then let's you know at 5 to go ahead with the booking and then having to go back and tell him that the $2100 to Sao Paulo is now $3300.

As has been discussed on this forum numerous times, the seat map is a very poor indicator of how many seats have actually been sold. There are numerous ways that you might buy a ticket but not have a seat assigned. Trust ExpertFlyer much more than the DL.com seatmap.