Description of Osprey Packs Waypoint 60 Backpack - 3700-3900cu in :
You've got a whole world to see and only one lifetime to see it in. The Osprey Waypoint 60 Travel Pack, with its thoughtful features and logical design, won't slow you down. Designed to make your minimalist world tour more manageable, the Waypoint first and foremost sits comfortably on your back when you're tromping around the planet with padded, molded shoulders and a Spacer mesh backpanel. When it feels like the world is on your shoulders, or if the airlines make you check the big bag, you can detach the smaller daypack from the back of the Waypoint and check the big cargo section. The Straps on the large section tuck away to protect them from bag handler abuse. A front pocket (part of the daypack) is perfect for passports, tickets, or whatever, and a magazine slash pocket gives you fast access to the obligatory trashy airport or bus station reading. The trip is defined by the journey, not necessarily the destination. Where you are now is just another Waypoint.
I bought this for a European trip thinking "no checked baggage". The bag is 28" long, and the test bin at check-in was 22". I carried it on anyway, hey, big airplane, big overhead bins.
On the return flight, I'd accumulated some additional stuff, and there was no way I could carry this stuffed bag on with a clean conscience. The small detachable bag worked fine as advertised.
Overall quality is exceptional, and buy the optional shoulder strap if you'll use as luggage vs. backpack.