Choose Duck Island and the Frozen Fire, or any other fast plane with cluster bombs. Armor doesn't matter since you don't plan to get hit. Fly in circles or figure 8s in the center of the map, dodging attacks when necessary. You'll know you got hit if you hear a slight buzzing sound and your score multiplier has reset when you kill an enemy. The first wave of Duck island has 15 enemies - get the multiplier up to 9X (the max), lure the last few enemies to their deaths, and you'll get this.
After you get Survivor, you can also get Big Guns with only five more kills, so don't relax until you have them both.