This story-related Achievement is awarded near the end of Chapter 15 when you rescue Jenny from the plane.
When you first approach the plane on the runway, unload on the nearest propeller. Then take out the guards at the end by blowing up the fuel tank next to the first set of jeeps, and open fire on the second set of jeeps to set them off. Then focus all your attention on the remaining propeller. If you don't get it on time, the plane will start to take off and crash, failing the level.
Once the plane has been grounded, slowly approach the rear and take out the enemies as soon as you can see their legs. Switch to the pistol when you go for the final enemy in the cockpit, so you're less likely to kill Jenny with a stray bullet. The Achievement will unlock once you approach Jenny and the cutscene begins.
This can be earned on any difficulty level, so drop down to easy if you're having troubles, or just want to earn it more easily.