Originally Posted by
highupinthesky
With the A350 being about 14 inches wider than the A330/340's and the eco seats being 17,3 inch wide means you only need to make the aisles 3,3 inch narrower to keep the current seat width or 1.65 inch per aisle. I will be surprised if there isn't 1,65 inch available in each aisle, but time will tell.
Edit: according to seatguru,
Lufthansa has 17" seats in a 3-3-3 config in eco and 18" in a 2-3-2 config in PE.
Singapore airlines has 18" seats in a 3-3-3 config in eco and 19" in 2-4-2 config in PE.
Delta has 18" seats in a 3-3-3 config in eco and 18,5" in a 2-4-2 config in PE.
I would guess SK will go with 18" as a minimum given the competition and limitations built into the A350. 17" is rare even for regular economy for other carriers with the A350, outside of the LCCs.