When playing through the main story you will complete a mission at an airfield, and afterwards you will be allowed to buy it for $150,000. The property is called the McKenzie Field Hangar.
After purchasing the airfield, you unlock the arms race missions which involve you using a buggy or a plane to pick up/deliver packages(and bombs later on). After completing five of each you will obtain the trophy.
Here is a Achievement Hunter video to illustrate;