Seat assignment was changed
 

I booked NRT-TPE months ago and selected seats 35J and H, a nice 2 person exit row. (Still have printed itinerary showing this) When I checked in today we had been moved to 51J, H. Still an exit row, but not as nice, and 35H showed as occupied.
Any idea what could cause Delta to do this? Does it seem I could complain my way up to EC?

Happens fairly often. Sometimes due to an equipment change, and sometimes for no apparent reason. As much as it sucks, seat assignments are not guaranteed. You're lucky you ended up in another exit row... people have ended up with far worse. I wouldn't count on being assigned an EC seat, but it never hurts to ask if that's what you want.

if same equipment, then your seats were probably "zapped" which is not supposed to happen - a big no-no (exit row would not qualify for caveat of pax with special needs, since shouldn't be in that row anyway). It's in the history of the record who did your seat move...

It really is imperative to check seating assignments on a regular basis especially on flights booked well ahead of the day of travel.

I was recently moved from 2B to 1B. Was it a flight marshall? Isn't it a security risk to expose him this way?

Think about it, you have no idea if it's a FAM. It's easy to provide cover for a move such as that. We cannot even say if it's a 50-50 chance.

True, but 2B is classic FAM. Any other seat...

True, but even if you check every 5 minutes, when once you find that you've been moved and someone else is in the seat you chose, you are usually screwed.

I usually set EF alerts on my seat assignments. Then when I'm booted out of them, at least I'll have the best shot at getting them back, unless someone else is assigned to them right away.

Can't do that for EC, right?

You can. EC seats show as blocked when they're not occupied, so you just set your alert to include blocked seats. Then when the seat changes from occupied to blocked, you're notified.

^

EF?

ExpertFlyer

Seat Assigment Switched from EC to Coach
 

Same thing happened to me. I had 2 seats booked in EC and there was an equipment swap and now I'm at the back of the plane and EC is full. Is there anything I can do? They stuck me and my son in the back of the plane. I only made the reservation 6 months ahead of time. I'm lucky that I happened to look.