How big a backpack is carryon on a USA airline?

First, off, it should be either/or. No need for both. A backpack the size you are suggesting will not be acceptable and you would not be allowed to have both as carryon. Not sure about the breach and observance. We were on a five leg domestic flight with Delta this past summer and three times the carry on went into the box at the gate and once we flunked. So don't take that lightly on international flights. The return flights from Europe are far more strict than outbound flights. And I have heard some ugly discussions about that. Have also stood in a couple of stateside check in lines during which every bag went into the box and most of the wheeled luggage failed.

The last couple of times I have flown, I have seen people stopped from taking their carry-on luggage on the plane that was too big. Their only option at that time was to check the luggage. Also, I have seen a few people actually get on board with oversized luggage that would not fit into the overhead bins, and were forced to check their luggage, delaying the flight and incurring the ire of the other passengers. I don't even try to carry on bags anymore, as everyone is tryng to save checked bag fees, and therefore carrying on EVERYTHING. I have even seen people have to check their bags once they boarded, as all of the overhead bins were stuffed. The airlines seem to be geting very strict with the carry-ons that are required to go in overhead bins. If there is any chance you will be flying on a non-US plane, such as hopping on BMI to cross the English channel, you had better double check the requirements, as they are very strict, and the weight limits are much smaller than US run airlines. Their overweight limit fees are very high.

Hey Frank, Thanks! I'm glad for the advice on the return flights in particular. And I admit I'm surprised hearing the airlines actually do use those frames! In all my years of flying--and that's a lot, domestically and overseas--I really have NEVER seen one used, either voluntarily by a passenger or on demand by the airline! So now I know otherwise! I'll reconsider my plans!

I travel a lot for business and also overseas to visit family & friends. I don't see a lot of bags being tested in the box. But I will say that I have a backpack the size you are talking about as I needed to live out of that one pack for an entire year and have clothes & gear for multiple seasons. I always had to check that pack. My pack did have a detachable day pack about the size of a book bag, so that's what I used as my 1 carry-on as it was just big enough to carry a change of clothes & my toiletries. Even if you found something that meets the dimension requirements of the airline, a lot of budget carriers in Europe are very strict about weight. So if you stuff a small pack to the gills you can still be subjected to checking it or paying a hefty fee to check a bag at the last minute.

Thanks, again, all. I guess I need to do some more packingplanning! I want to have the flexibility to switch from dragging a rollaboard to using just a backpack for short trips if I leave the rollaboard behind in a hotel/hostel I'm coming back to a few days later, for instance. I also have to have enough space not only for basic clothing (I know how to pack light) but also the 7 weeks of my diabetic stuff I have to have with me. Not just the insulin; the stuff I put it in so I can use my pump takes up space and I can't count on finding it while I'm away from home so I MUST take it with me! I set out all the stuff I think I need, and it would fit in one big non-carryon-suitcase (not my first choice for obvious reasons) and would also fit in my rollaboard plus either of the two fairly good-sized backpacks I now own, but NOT in my rollaboard plus my day pack! So that's what gave rise to my OP question. Thx for the input. You win by knowing what not to do, and this is now a win for me, sorta...I just got to figure out what TO do now.

The closest thing is probably a convertible carry-on. Rick Steves, Campmoor, Ebags and a few others offer Convertible Carry-On bags that are built about the max size allowable for a carry-on and include backpack straps and waist belt. In my experience, true backpacks are longer than 22" and can't be carried on - which doesn't work for me. I've heard REI may sell something that works but haven't seen it. I rarely carry my bag enough to need a true backpack and I like the suitcase like features in the convertibles.

Tom, I suppose that if airlines are more strict these days about the carry-on rules it is because charging fees for bags is a new source of revenue. More incentive for the airlines to force bags to be checked. In addition, more people are trying to carry on bags to escape the checked bag fees, which means there is more luggage being hauled on to planes and there often isn't enough room. More reason to do some weeding out before people enter the plane.

That may be true for domestic flights but most international flights are allowing free checked bags even in coach.

Frank, isn't that true for just the first checked bag? I'll bet some travelers dragging wheeled carry-ons down the aisle have already checked their first bag and are trying to avoid the fee for their second bag. I think the packing light religion is still seeking converts as most folks are still packing infidels.

Check out Rick's Travel Store at the top of this page! He has a new convertible rolling backpack.

I've been able to get on Continental several times with a 21 inch rollaboard and the campmor convertible worn on my back as a squishy, nonstuffed pack. One in the bin and one at my feet. Have also been on Delta a few years ago with a full size Kelty backpack ( still squishy and near the 45 inch rule) and the rolling suitcase. Haven't been checked, but only have that much stuff on the way home these days.

Here is a chart that compares some of the bigger airlines (mostly American): http://www.luggageonline.com/about_airlines.cfm Again, if you are planning on going anywhere NEAR a European airline, they are much more strict, and I would advise bringing a small, lightweight bag you can move valuables into in case you are forced to check your main bag (not a bad idea, in any case).