Originally Posted by
findark
I think it's pretty well established that the primary, and probably only, factor is your current seat assignment when the equipment is swapped. It's the exact mapping that tends to make no sense.
watching the seat maps just after a swap back, UA seems to avoid assigning the “middle middle” seats in the 2-4-2 section unless required due to loads. For example, when my flight swapped back, 7-9DG were left open (with all other seats assigned), and, on another flight I was watching, 6-10DG were left open. Given the scattered nature of the open Polaris seats just before both swaps back but the concentrated nature after, I don’t think there’s a 1-1 Polaris to 3-class mapping.
Instea, I think UA assigns windows to windows, then aisles to aisles, etc, leaving the middles to last. In what order they assign Polaris seats to 3-class is TBD.
(There does seem to be a 1-1 interim to Polaris mapping though)