There are post like this that I found but involves your enemies pet using dive or fly this involves YOU using fly.
1. Have a pet with fly like a onyxian whelpling
2. Have a dot ability like immolate or scorched earth
3. Now when your enemies battle pet is almost dead use fly
4. Attack your target till hes low health
5. Use fly
6. If your enemies pet dies of the dot your pet will stay in the air with the full capability of attacking while not leaving the air phase
Make sure to check all the variables such as your pets speed, if your dot is strong enough to kill your target while in the air, etc.
(Works for pvp pet battles only i believe)