Alright, as everyone know when you've got a mount that changes depending what zone you're in and scales along with it (ie touring rocket) you need to dismount and mount up again when you change zones to get the benefit.
Go to Krasus' landing and mount up, you can fly.
Fly over to the well in dalaran where it lets you fly without being dismounted, land on the grass there and you will notice you can't take off again but you still have the flying mount. You can run around with the mount and when you run to Krasus landing again you can instantly take off.
I'm looking into different ways to use atm.
Before you say it's working as intended, you need to dismount and mount to change the effects and you don't need to here. When you land you can't take off again but you keep the flying buff.
Edit: It seems if you log out in the sewers after landing by the well you can fly in the sewers without getting dismounted.