The campaign of Ace Combat 7 features a few mini-bosses - aircraft or drones with better maneuverability and speed than the regular enemies. The fights don't differ from standard dogfights.
Arsenal Bird, a huge aircraft transporting drones, is a true boss. You won't be able to do anything to it during your first encounter with this enemy. In the next fight, your goal is to focus on destroying the aircraft's key parts that activate one after another and are hidden among numerous turrets.
From time to time, the Arsenal Bird will surround itself with a blue field - your missiles won't go through it. You need to wait for the field to disappear and then attack again.
First, focus on two main propellers. After that, destroy sub propellers. Place yourself behind the Arsenal Bird and attack it. Decrease your speed to avoid hitting the boss. Watch out for the drones. Avoid the enemy missiles and move your aircraft away from the boos from time to time.
After destroying the propellers, focus your attention on two Joints. Attack them from behind (place your aircraft at a slightly lower altitude than your targets).
Next, you need to destroy objects called Hook. Even though you lock on them, your missiles can miss the targets. Find the right direction from which you can attack. Attack from a side or from the front, but always stay below the boss.
Finally, an APS Unit will get revealed on its undercarriage. Go down and attack the unit while flying upwards vertically - you will get a clear view on the target.
Destroy the boss and watch it fall down into the sea. Bravo, you have defeated the Arsenal Bird in Ace Combat 7.