Nearly 30% of seats are sold last minute on INTL flights?!?
 

I was an a number of TATL and TPAC flights recently that sold over 30% of seats within 72 hours before flight. This is really surprising for international flights when you expect more people plan in advance vs domestic flights. I consider myself a last minute traveller and often complain about unavailability of good C+ seats 1 week before flight, now I see that I am not as "last minute" as others.

I take my numbers based on "seats available" counts in "upgrade/standby list" option in the App. Maybe the numbers are reported not very accurately but they more or less correlate with seats available on seat map, so I think the numbers are not too far from reality.

Recent example on a 777:

2 weeks before: 130 Y, 20 J
1 week before: 120 Y, 18 J
72 hours: 100 Y, 15 J
48 hours: 70 Y, 7 J
24 hours: 50 Y, 5 J
12 hours: 30 Y, 3 J

Another question: why DL makes this information on seat counts available to anyone who booked the flight? Can it be used by competitors to research market / loads?

"seats available" isn't the same as "seats available to be sold".

There are a bunch of people with confirmed tickets who don't have seat assignments (basic economy pax, plus anyone else who didn't get a seat assignment for whatever reason)

This. "seats available" means seats unassigned, not unbooked. It's not uncommon to have 30 or 40 people with unassigned seats even on an MD88 24 hours prior to departure (the highest I have seen is 79 on an MD90). So in reality, you could see that "seats available" number drop from 80 to 0 in 24 hours without a single seat actually being sold.

The "seats available" definitely isn't an accurate representation of how many seats have been sold on the flight. it doesn't account for passengers that have economy basic tickets as well as passengers that simply never selected a seat.

Are you saying that "Seats remaining" on "Upgrade and standby" list in Delta App = number of unassigned seats?

Correct.

I am surprised there was such a big swing in seats open between the 72 hour mark to the 12 hour mark Maybe there was a sale?

No. While undoubtedly some tickets were sold, it's just a factor of people checking in and selecting (or being assigned) seats. The seat map or 'seats available' has nothing really to do with the instantaneous load factor.

I thought DL checked you in automatically at T-24?

Yeah as others said, its because those 'seats remaining' are actually just unassigned seats, not seats available for sale.

At the airport gate information display it will have the current/accurate count of seats actually available on the plane while they are displaying the upgrade and standby list status.

The automatic check-in only seems to happen when you open the app based on my experience. BE pax may or may not get a seat at this point depending on availability. Many reports of BE seat assignments going to the gate.