There was a post here a ways back about Alaska Airlines having 32” of seat pitch in economy on the 737 Max 9 on the starboard side of plane rear of the exit rows. It’s not much, but with Delta, American, United and Southwest offering 31” (or less!) in coach BEFORE reclining occurs, an inch is the difference for a tall person between being able to sit normally on a 6 hour flight to Hawaii or Alaska, or having to point the knees 15° one direction and then contorting to point them the other direction, switching back and forth every 10 minutes as limbs go to sleep.
I am happy to report that this appears to be true! Not only could I sit normally the whole time on both flights (3+ hours row 19, 6 hours row 21) but miraculously when Alaska seats recline the bottom doesn’t move back! The top swings back but the bottom half stays stationary so knee space for the person behind the reclining seat is unaffected. I am an engineer and couldn’t figure it out, but as they say a game changer for me.
Note that I didn’t try the seats across the aisle so maybe this is true there also and other places in coach on the Alaska 737 Max 9.
Here’s the source
https://www.aerolopa.com/as-7m9
Also noting that the middle seat is noticeably wider than the window and aisle seat on this plane, an interesting egalitarian design approach I’ve never seen before. A heavy person might not like the window or aisle on this plane.