I tool a flight from Montreal to Paris 7 hours flight ( 1 hour ) stop in Paris then from Paris to Tunisia ( 2hours flight ) . Royce is the same weight as your boy .
make sure that his carrier is the biggest size allowed in cabin .
Make sure you take with you water nutrical treats and pee pads .
With Royce they told me he is not allowed ou of his carrier but his carrier has a small window that I can open and he can poke his head outside also I kept the other side of the carrier open .
I would take him to the toilet to make him pee on the pee pad every 2 hours place the pee pad on that foldable table thing thay they use for babies
Also make sure he drinks water every two hours .
During the flight from Montreal to Paris the crew told me the he has to stay in his carrier but I ignored that and I would take him out whenever they are not around . and anyway he slept most of the 7 hours flight
In Paris he was on his leash and I mahe him play and walk .
The flight from Paris to Tunisia was short ...
On my way back I was business class they allowed me to use the empty seat next to me for Royce and Royce was on my lap or sleeping in his seat for the entire flight back to montreal and the crew went crazy because he is so cute evry 15 minutes each one of them would come to pet him or give him water ....I was lucky