Originally Posted by PDX-PLT

if the flight is a codeshare for another carrier, there can be lots of reserved PAX without seat assigments. I took 128 NRT->SJC last week, which is a JAL codeshare. I almost switched to one of the aisle seats in the midde section, since the seat map was very empty and I thought I could grab 2-3 seats together. I'm glad I stayed in 31H, since all those "empty seats" ended up getting filled with Japanese nationals, who I'm sure had booked under the JAL flight number and thus did not reserve a seat.