Parachute Deployment Sequence
Here's what happens when a parachute deploys normally:
- The skydiver uses the pilot chute to start the deployment sequence. The drogue normally rides in a little pouch attached to the bottom of the container (BOC). To deploy, the skydiver pulls the drogue out of the pouch and lets go of it.
- The pilot chute catches the air and inflates. It pulls out a 7 to 10-foot long (2 to 3-meter) piece of nylon webbing called the bridle.
- As the bridle is coming out of the container, it pulls a pin, called the closing pin, on the container. This pin holds the main canopy inside the container. Pulling the pin opens the container with a small pop.
- The bridle continues to pull out of the container.
- One end of the bridle connects to the pilot chute. The bridle's other end connects to a bag called the deployment bag, or D-bag. When you pack the parachute, you stuff it into the D-bag, and then load the D-bag into the container. The bridle pulls the D-bag out of the container.
- All of the parachute's lines have been stowed in a zig-zag pattern by looping them underneath rubber bands attached to the D-bag. As the pilot chute and bridle continue to pull on the D-bag, all of the lines unfold and stretch out.
- As the lines completely unfold and start to pull with the tension from the pilot chute, they pull the risers out of the container. The risers are heavy nylon straps that connect the lines to the container. (The risers also contain a release mechanism for the main canopy's lines in case you need to cut the main canopy away.)
- The tension on the lines also pulls the parachute itself out of the deployment bag.
- The wind inflates the cells of the canopy. What you do not want, however, is for the canopy to open instantaneously. If it opens instantaneously, you go from 120 mph to 10 mph too quickly. This hurts and can also damage equipment -- it can snap lines or rip the canopy. Therefore, all ram-air canopies have a piece of nylon called a slider that holds the lines together and slides down the lines as the parachute opens. This slows down the opening and keeps the lines from tangling as the parachute inflates.
Once the parachute is out and open, the skydiver looks up to make sure everything is OK. Then the skydiver can grab the two toggles and start steering the parachute toward the landing site.
Next, we'll look at what happens when the parachute doesn't deploy correctly.