Michael gave his usual good tips on how to survive getting gear on your flight.
I thought I would mention my experience in using the Think Tank Security bag on Icelandair. The Security rolling bag is a very slightly bigger version of the International(14x9x22 inches versus 14x8x21). It didn't make any difference how much it weighed. The airline ticket counter agent said it was physically too big for carry-on and made me check it. I took out as much as I could and put it into a smaller, spare collapsible carry-on I had, but my Canon 500mm had to be checked. Argh! (It arrived, no problem.)
I have since invested in a vest to use like Michael suggests. Plus, I bought the Glass Taxi from Think Tank. It is a very small bag that will carry the 500mm. I think it is the smallest bag that can handle that lens and at 17” H x 8.5” W x 9.5” D
should pass for carry-on even with the small commuter jets. I won't be checking the 500mm again.
Now, my carry-on baggage consists of a Domke vest, the Glass Taxi, and a small roller (forget the brand name) that can hold laptop/camera/accessories/lenses.
Good luck out there!
David