If you're getting close to level 12, you wanna make sure you stay very close to the airport...
I noticed that if you finish a level right where the underground tunnel comes out to go by the airbase (on the west/ocean side), then you're in a zone where the next level doesn't spawn yet... you can actually fly over the water, all the way south under the airport... then creep up that runway that hangs off the land... (going north now)... once you get in range, the spawn will happen, and since you're down in the very far corner, 95% of the time, the next spawn will be in the airfield. I've had really good luck with it... (until my game freezes at level 100... sigh)
- bbitto
I noticed that if you finish a level right where the underground tunnel comes out to go by the airbase (on the west/ocean side), then you're in a zone where the next level doesn't spawn yet... you can actually fly over the water, all the way south under the airport... then creep up that runway that hangs off the land... (going north now)... once you get in range, the spawn will happen, and since you're down in the very far corner, 95% of the time, the next spawn will be in the airfield. I've had really good luck with it... (until my game freezes at level 100... sigh)
- bbitto