What plane is this Finnair seatmap for?

Question

I was examining the seatmap for a potential flight on Finnair flight AY131 from Helsinki to Singapore, and spotted something quite odd. Per Flightradar24, this route always operates with the pride of Finnair's fleet, the Airbus A350-900. However, on some days in April, the following seatmap pops up:

...

This matches neither of Seatguru's two layouts for Finnair's A350-900 for Finnair's 359s: note how the middle section of the front seats is excluded from "Economy Comfort" section (starred seats), and how the last seat number is 66, not 56. This last tidbit is particularly odd, since Finnair's only other twin aisle jet (A330) maxes out at 57 rows.

What is this aircraft? Is Finnair temporarily chartering somebody else's plane, or is this a revamped A359 which already has Finnair's upcoming Premium Economy offering, which is scheduled to launch officially on May 11th?

Answer 1

Trying to pick a seat on the flight on April 2nd on the Finnair site yields:

It's still a 350, but there are 3 rows (21 to 23) which have a 2+4+2 layout, while rows 31 to 66 have the usual 3+3+3 (with the usual random exceptions).

This seems to match Finnair's new Premium Economy layout:

Finnair says the pitch in the new Premium Economy is 38” (96.5cm).

There seem to be 3 different types of seats:

• Standard

• Comfort (starred, still 3+3+3, rows 32 to 34, A-C and J-L)

  Get at least 7.5cm more legroom

  But other than a bit more legroom, they seem to be exactly identical to standard Economy seats

• Premium (2+4+2, rows 21 to 23)

  • 17.5cm (7") more legroom than in standard Economy seats
  • Larger, comfortable seat in a private cabin
  • Easy boarding and exit
  • Larger personal entertainment screen

  Those seem to be better seats. No word about width (though 8 seats instead of 9 per row should make a bit of a difference) or exact recline, though, they only tell us:

  Better seat recline and a leg rest supporting the whole leg