Departure flight was changed after I departed
 

I was on a DEN-SEA-DEN flight leaving this afternoon and returning later this week. When I arrived in Seattle, I noticed that my itinerary showed an extra DEN-SEA segment departing tomorrow night. The website says that "A modification has been made to your itinerary" and to contact United for re-ticketing.

Looking closer at this new segment, I saw that I had been assigned the same seat I was sitting in this afternoon, but one that doesn't exist on the equipment used for tomorrow flight. I was able to select an exit row seat. But even though that seat now shows as occupied, my seat assignment has not changed.

I'm curious to see if this clears itself off or whether my return will get cancelled when I don't show up for the phantom flight tomorrow.

Siting back and waiting to see what happens is really a great strategy in this case. Best to call and get it straighten out before missing the flight creates a problem.

Yes, I too thought doing nothing was a great strategy :) It's part of my continuing resolution to take things as they come and to observe the world more when traveling.

But since the system wouldn't let me check in to tomorrow's flight or change the flight to anything earlier than next week, I went ahead and had the segment removed. Apparently, it was the result of an overzealous automated process that rebooked flights cancelled due to weather.

Whenever UA adds (duplicate) segments to an itinerary they will always show the wrong seat assignment and it will match the one you were originally assigned to.

So when they added another DEN-SEA segment which matched a DEN-SEA segment you already had earlier in your itinerary, the seat assignment will show the same for both segments. You cannot actually change the "backup" segment seat assignment. The map may appear, it may look like you selected your seat but it will fail and revert back to what it previously showed.

Agreed - do not wait for UA to 'fix' this automatically. If they really think you're going to be on DEN-SEA the next day and you don't show up then they will cancel your SEA-DEN return entirely.

-RM