The Case For Rubber Bands.

A visiting skydiver deployed at the appropriate altitude and his canopy opened into an almost perfectly symmetrical bow-tie shape. Wisely he cut the canopy away quickly and landed his reserve safely. The canopy landed in a 60ft tree, and upon retrieval we started the process of analyzing what had caused it. The rig is a nicely maintained Mirage with a Triathlon main.

However, rather than use the deployment bag which came with the rig (and which is TSO'd as a part of the rig), this jumper decided to use a main bag provided by Aerodyne when he bought the canopy. It was made of F111 canopy fabric to match the center cell of the main canopy (like that matters) and instead of using rubber bands he had used "superbands" and had actually double stowed some of them to maintain tight line stows.

The canopy reached line stretch, but the bands would not allow the canopy to leave the bag, it did however start to inflate and deployed THROUGH the bag, shredding it and wrapping it around the slider and bridle and pilot chute, effectively tying the center of the canopy closed.

What did we learn today?

1. Use the equipment recommended by the manufacturer. I have helped Mirage with some drop testing and they are very thorough and stand behind their gear.

2. Use mil.spec. rubber bands. They are cheap, easily replaced and, as John Sherman of Jumpshack outlines in the technical section of their website, they "break for a reason", which is to let the damn canopy out of the bag. The line stows are a key and integral part of the deployment process, the distribution of the lines and how they are retained directly affect how the canopy will open (or in this case not).