If you have a reservation you made fairly far in advance (say, more than 3-4 wks.), here's a reminder to check on it at least weekly.

My most recent experience has been with Delta, but other airlines tend to do the same thing.

I made Thanksgiving reservations in August, knowing the flights would fill. Twice since then, on my weekly check of my itineraries, Delta deleted my seat assignments and left a "no seat assigned" notation in the record. Since those flights were now completely booked, this was alarming.

Both times I called Delta and they "explained" that because there'd been a "minor change in flight times" (about 20 min. difference), the seat assignments had been "revised." I demanded that they reinstate my original assignment and make a notation in my record that, for medical reasons, I needed the seat they'd assigned me and it should not be switched.

(yes, yes, yes, I know no seat assignments can be guaranteed, but I can still request a notation be put in the record to stop an agent from arbitrarily switching me -- a lone traveller -- to another seat so some party can travel together, which happens all the time. And the "medical reasons" are valid, though NYB.)

The second time, the agent noticed that there was, indeed, that notation in my record; and she reinstated the seat assignments.

But once again: It's been said often, but as the holidays approach is worth saying again, KEEP CHECKING THOSE RESERVATIONS -- for times, flight numbers, connections, and seat assignments. They're going to shuffle and switch, and most will not notify you that they have.

Merry Thanksgiving and Jumpy Halloween to all.

Often when you make the reservation, you can ask to be notified automatically by email. This saves you trouble and them money. Just be sure to open every single piece of email from your airline.

Was there an equipment change or just a schedule change? I've had several schedule changes (including flight number change but no change of equipment) on my DL itineraries and they've kept my seat assignments. When I look at my itineraries on delta.com, it will say "no seat assigned" until I call and have them clean up the record, but my seat assignments are still there, just not visible online. Anyway, it's always a good reminder to check your itineraries often regardless of the airline.

Yes--good reminder to keep an eye on your itineraries. We had an itinerary change this week for holiday travel, as well--United ticket, but the change was on a codeshare flight operated by US Airways.

I lucked out, in this case, getting a great, proactive agent when I called in for information about the change. Although I was set to approve new itinerary (basically going from a US/UA connection in Philadelphia, to a US/US connection in Philadelphia), the agent said that the schedule change gave her the authority to change the ticket to a non-stop UA JAX-ORD flight instead--one that I didn't book in the first place because it was much more expensive than the connecting flight. And because we eliminated the connection, the airport fees went down and I got a little money back in the process!

HKP,
I am also traveling Delta Thankgiving week nad booked a flight in May, so I have been going through this also.
After the second time calling a rep told me that my seats are still there, they have not been deleted, I can just not see them. So they update the website while I am on it and there they are. She told me not to worry the seats are still assigned even though I cannot see them.
So don't panic-just call and they will update your info and you will see your seats again.
I have had to do this 4 times already and never have had my seats changed.

Things change all the time, so we need to be watchful. On one particular flight, the gate changed with no announcement of such after I had already checked in. I just happen to be walking around and so that my flight had been changed to a different gate.

DELTA: best airline ever!! whoohoo!!

We all seem to be told the same thing -- that the seat assignments aren't changed, we just can't see them.

Forgive me for caution/paranoia, but I suspect those people who don't call and demand to have the assignments made "visible" again may risk having them disappear altogether and it'll be first-come, first-seated on the day of departure. With over-booking (and all these flights are over-booked), the people without confirmed "visible" assignments may well be the ones told to wait to see whether they can be seated or not on that particular flight.

Ought'n'to be like that, but 'tis.