Originally Posted by SuperEWR

1. That's exactly the point, UA feels like they have demand for more J UA's route network than DL does on DL's route network because they are different carriers flying a different route network out of different hubs. It's not just a question of relative density of Polaris vs D1 seats, because if you do the "basic math" (and I did), it's clear that UA is not just cramming more J seats into the same square footage as DL, but that they are dedicating a larger proportion of square footage to J than DL. The question a previous poster posed was why does UA do that (and the answer at least in part goes back to the different route network out of different hubs, but the conversation hasn't progressed that far). As to whether DL wants a larger D1 cabin, isn't the entire reason for this thread that DL wants and is about to buy / reconfigure A350s with a larger D1 cabin? I think they clearly want a larger D1 cabin than what they have been flying, and generally speaking a long-haul carrier will prefer to have larger J cabins if adding J seats doesn't meaningfully dilute yields that were strong to begin with, as it is the J (and to a lesser extent PE) cabin where the profits are made on long-haul. This is quite clear when you look at how airlines configure fleets for leisure vs business destinations and from extra-premium subfleets like UA high-J 767, SQ's A350-900 ULR, and QF's Project Sunrise A350 (there's not a "regular" QF A350 to compare against yet but if looking at it against their A380 which the Sunrise A350 will take over from on routes like QF1/2, it's pretty clear that relative to the square footage decrease when going from an A380 to an A350, the F and Y seat counts were cut at a disproportionately high rate while the J and PE seat counts were maintained much closer to the A380's J and PE seat counts)
2. There's only 9 ex-LATAM A350s, even with the additional new high-J A350s that's a pretty niche subfleet in the low double digits which is comparable to other niche extra-premium subfleets (UA has 24 high-J 767s, AA has 17 A321Ts, QF intends to purchase 12 Sunrise A350s and SQ has 7 A350-900 ULRs. I don't think anyone is arguing that all of those are niche sub-fleets for their respective carriers). Unless DL decides to add significantly more high-J A350s and / or reconfigure the existing 32J A350s to the high-J configuration, 9 ex-LATAM A350 conversions and a handful of new high-J A350s is undoubtedly a niche sub-fleet
3. I think it's pretty clear Mountain Explorer was referring to the amount of square footage 1 J seat takes up given they were talking about being able to fit more Polaris seats in the same space allotted to a certain number of D1 seats. My point is that square footage differences alone (or even square footage + plane size differences) do not explain why UA has so many more J seats than DL for planes flying comparable routes