If you haven’t flown in a couple of years it probably isn’t. A couple of years ago American Airlines changed the allowable dimensions for an airline carry-on and now have size restrictions in place. Other airlines followed their lead and adopted the same restrictions.
These are the allowable airline carry-on dimensions from the American Airlines website. “Up to 45 inches (22 x 14 x 9 in) or 115 centimeters (23 x 36 x 56 cm) including handles and wheels”
In addition there’s also a 20 lb. weight limit in place for an airline carry-on.
Fortunately for me I found out about the new limits before I flew to Ecuador last October (2014). The airline carry-on that I’d used for years was obsolete. I had to go shopping for another one to satisfy the new restrictions.
After quite a bit of research I settled on a High Sierra Swerve Backpack. Overall Dimensions: 19 x 13 x 7.75 in. It has a padded laptop compartment and a host of other features that worked perfectly for me. My plan was to use it everyday once I got here so I had that in mind when I bought it also.
When I flew to Cuenca, Ecuador last October I had a stop off in Mexico City and again in Quito. At both locations they put my carry-on through what they call a sizer that checked the dimensions as well as the weight. I sailed through both locations without any problems.
As a backpack for everyday use after I got here it’s been fantastic. I carry it with me everywhere I go and after more than 10 months it still looks as new as the day I got it. Here’s the link to read more about it.