How do I play this mission solo?
1. Go to "offline missions".
2. In the list of missions, scroll down and find "Defend Berlin" and click it so that it has a blue border.
3. Click "download" button.
4. Click on "Fly for - Axis"
5. In flight drop down choose the plane you want to intercept with,
Hit "OK" and the mission will auto-load and start.