Your first free-fall section will be near the end of Chapter 4: No Way Out. To get this you will need to hold the down. This is a lot easier than it sounds. You can die as many times as you want, as long as you don't let go of the button it will still count towards this achievement. When you spawn again and are holding it, the game registers it as the whole time even after passing checkpoints. A good tip though, is whenever there is a blue X looking marker showing up, it means you will run into that object. Just press the appropriate direction on your analogue to avoid collision. Do not think you must navigate the entire time. Let the game do it for you. Your only roll is to press the right directions (for the most part).
Free-fall Chapter Locations
1. Chapter 4: No Way Out - 1 free-fall
2. Chapter 8: Here There Be Monsters - 3 free-falls
3. Chapter 10: MJ on the Run - 1 free-fall
4. Chapter 14: Nowhere to Run - 2 free-falls