This topic also got started on the CO board this week by a flight attendant:

Interesting thing to note a major difference in policies within our alliance...

- Continental allows any carry-on within 51 inches of total linear space.

http://www.continental.com/travel/po...e/carry-on.asp

- Northwest (and Delta) allow only 45 inches.

http://www.nwa.com/travel/luggage/carryon.html

That would make many wheeled garment bags, like this one OK on CO, but not NW:

http://www.luggageonline.com/product...roduct_ID=6043

So, point to note...

Many of us fly both carriers. If you like to use these bags, do as I do, and stick with CO for most flying, as it's perfectly legal when properly packed. If you despise them...have fun fuming on Northwest, where it's perfectly within your perogative to police them.

If you don't like the CO policy, don't fly them. I only have NW status as a legacy from days living in MSP. Most of my flying is on CO. For what it's worth, when on NW I ask if the flight is full, and if it is, gate check.