Breaking news: The rumors are true. After years of open-seating, Southwest is rolling out assigned seating beginning July 10 for 200 flights originating in San Diego. The test period is unspecified, but will last “several weeks.”

Crucially, the test will determine if a 25-minute turnaround between flights is viable with assigned seats. No word on how they will be boarding the planes, i.e., whether they’ll keep boarding zones on the basis of check-in time, or if they’ll board by rows, back-to-front, “wilma,” “reverse pyramid,” etc.

This is a huge move by Southwest, and an admission that the open-seating model isn’t a customer favorite.

I’m betting they’ll still keep the A/B/C boarding groups. Just two weeks ago, Southwest sued third-party sites which checked passengers in early, to assure an A-group boarding pass.

In any case, we’ll be watching the test period with great interest. (Readers who fly Southwest from San Diego in coming weeks are invited to write in with reports.)

At the same time, Northwest Airlines just announced that they’ve quietly eliminated row-by-row or zone seating, though they kept seat assignments. They claim the move has shaved five to ten minutes off the boarding time. Why the speed improvement? My guess is that everyone is rushing on board to secure a space for their carry-on bags. Sure, you have a seat assignment, but you still have to fight the masses for the overhead bins. Sounds like fun.