This wingsuiter deployed their main canopy around 4,000 ft and had a pilot chute in tow for 9 seconds. The pilot chute got caught in the the wingsuit burble, did a loop, tied itself off, effectively killing itself and preventing a normal deployment. Once he realized the main wouldn't deploy he went straight to his reserve parachute, which is when things got a little messy. The reserve had some line twists, then the main deployed as well and got entangled around his feet! The jumper cutaway the main, took some time getting it untangled from his feet, and once the main flew away he cleared the reserve line twists around 1,800 feet.
This whole incident probably boils down to the way the jumper pitched their pilot chute. In their words, “I made a very weak pc pitch at 4000', and dropped it in my burble.” That’s actually a bit of an understatement because, if you watch the slow-motion portion of the video, you’ll see that the jumper actually grabbed their PC, went to toss it, and instead of releasing it at the apex of their pitch, they held onto it for a half second. By doing so, they lost the inertia given by their arm moving away from their body. That pilot chute had a slim chance of escaping the burble.
Wingsuit deployments are far more sensitive and prone to issues; you need to flare your suit, time your pitch, symmetry matters far more, and even your canopy choice has a larger effect on how your deployment goes. (While we don’t endorse any specific brands, our go-to suggested reading material on the topic is Squirrel's article about wingsuit deployments). This jumper’s mistake occurred when they didn’t make a nice strong pitch of the pilot chute, making sure it got away from their body and cleared the burble.
Some folks argue that, in a high-speed malfunction like this one, going straight to reserve is justifiable because there’s not a lot of time and you’re losing altitude fast. However, many experienced jumpers counter that if anything Is out – even a pilot chute – you should cutaway before deploying your reserve because by not cutting away first, your main is still attached and begging to entangle with your reserve. This video supports the latter argument because, had this jumper cut away before deploying his reserve, the main would have more than likely just fallen right out of his container and not posed an entanglement risk at all. It should also be noted that this could have been a lot worse; the main could have entangled with the reserve.
Some viewers may be curious as to why the main, which didn’t deploy initially, deployed after the reserve came out. When a reserve is sitting in a container, it puts pressure on the main, in turn helping the main keep pressure on the pin. When the reserve is deployed, that pressure is relieved, potentially allowing the pin to be extracted far more easily; even by a pilot chute that has been killed.