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Dette er en Must Read for mange, ikke minst de som flyr hoppfly. Videoen illustrerer godt problemene som beskrives godt i artikkelen. (Red.)

Sjekk video her: https://tinyurl.com/zmen8yxf 

Why This Flight Went Wrong

By

 Paul Bertorelli

November 7, 2021

Last week, my various inboxes filled up with links to the video posted here, attached to the question, “have you seen this?” How could I not? Shortly after it was posted, it rocketed around the skydiving village like a rubber check in a tile bathroom. I spent a couple of days last week doing intensive wind-tunnel training and we discussed it during our breaks. Suffice to say it’s one of a kind only to the extent that the stall/spin was dramatically captured by a videographer. It is hardly a first and as much as I might wish that publishing it here will make it the last, I know that this passing thought gives futility a bad name. My reaction to these things is often, “the things we get away with in this sport that don’t kill us.” It might deserve firsties for pinning five skydivers inside the airplane during the spin, however.

There’s a lot wrong here related to decision making, judgment and execution of what planning may have been in place. That means there’s a takeaway related not just to skydiving flight operations, but flying in general. It relates to just saying no sometimes. As described in the video summary, this was a workup jump to a 20-way event at a South African drop zone. Presumably those would have been with two-aircraft formations since a King Air won’t carry but about 14.

To my eye, the first thing that went wrong is that they took off in the first place. The exit was above a broken to overcast layer and although it was thin, the videographer’s footage shows it was right at the altitude where the skydivers broke off to gain some separation for canopy deployment. In freefall, I don’t like being in clouds, being near clouds, or going through them, period, much less with a large group. Deploying with zero visibility invites a canopy collision, especially if the break-off tracking happens in cloud with no visual reference.

When this jump unraveled, the organizer did the standard pull-it-out-the-bag salvage by signaling for a round formation. He may or may not have known five jumpers never got out of the airplane due to the stall/spin. Carrying on with some semblance of the dive made sense because that was the plan and keeping a group together for an orderly break-off is preferable to everyone careening around the sky looking for separation to deploy.  

Jumping in other than perfectly clear conditions requires judgment on the part of the drop zone operator, the pilots and the skydivers themselves. In my experience, the latter have the least ability to make a wise call because doing so means, at best, you may have to go around for another pass or just land with the airplane, usually losing the cost of the jump ticket. Horrors. So skydivers want to exit no matter what and many will. Sometimes, the pilot—who is on the enforcement hook for jumpers busting clouds—just has to say no to taking off in the first place.

This video reminds me of why I don’t like jumping King Airs. They are not a common jump ship, but because they’re relatively cheap, some drop zones use them in lieu of Twin Otters or Caravans. For aircraft, skydiving is a utility operation and Otters and Caravans, with big doors, fixed gear and hell-for-strong structure, are utility airplanes. King Airs are really business airplanes, with smaller doors and retractable landing gear which increases operational and maintenance complexity. One weakness of King Airs is a relatively narrow, aft-tending CG that means the airplane isn’t tolerant of six or seven people hanging off the bars and maybe a videographer perched out near the tail close to a CG station Beechcraft never figured was relevant.  

Skydivers know bupkis about center of gravity. They just assume if they can crawl out there and hang on until exit, the airplane will shrug it off. So the smarter dropzones and organizers who have been through stalls, brief the jumpers on how to do these exits. For every jump, we dirt dive the plan on the ground and set up and practice the exit in a ground aircraft mock-up. Sometimes several times. This is the point where the skydivers in the front of the airplane need to be reminded to stay there until that instant when the outside people are just departing and they can rush the door without causing a stall. In an Otter, you can put six outside and three close in to the door inside and the rest spaced out in the airplane and some forward. It is true that the forward-most skydivers will be delayed diving down to the formation by a few seconds, but better that than being slammed into the cabin walls during a spin entry.

I have been through two stalls in Otters, albeit no spins. I was standing outside for one and departing from the inside for the other. I knew what was happening, even if my fellow skydivers did not. I’ve seen this from both sides. (Sounds like a song.) I’m hardly a Twin Otter expert but I’ve flown enough Otter loads to understand what happens and it’s challenging to deal with it. The usual drill is to reduce power on the left engine and trim up for 90 to 95 knots indicated. When a big group gets out of the door—say eight or 10 perched for exit—the pitch moment starts heading north and it will continue to do that until they exit. If they’re slow about it, you know what’s coming when there’s no more elevator authority left.

So skydivers have to be briefed about this. Hang out there long enough and you’ll cause a stall. Or put too many out there and you’ll cause a stall. And that’s what happened here, along with a rolling moment and enough yaw to initiate a spin. The recovery was quick; it’s only about a turn and a half. I can’t tell for certain, but once the spin stops, there may be some secondary stalling going on during the recovery. King Airs build speed rapidly and the pilot said he wanted to avoid that and may have commanded pitch up too aggressively during the pull out. The pilot attributed the unstable rolling to one engine spooling up faster than the other, but I’m not so sure about that.

The jump organizer can and should have avoided this. The DZO and pilot should have made sure he knew not to put so many people outside and not to keep whoever was out there in place for so long. These guys didn’t discover this on their own. This has happened before and King Air operators know about it. Still, when skydivers get all amped up with adrenaline before an exit, they sometimes ignore the briefing. More than a handful of times, I’ve grabbed jumpers by the collar to haul them back from the door until a bigger group exits.

The most egregious example of this I ever saw was during the 400-way record skydives in Thailand in 2006. We had 410 people in five C-130s. The plan had been for two passes with 200-ish formations on each one, as practice set-ups. These were from 24,000 feet. So it was suggested when the first group exited, the second would walk to the back of the airplanes, pick up the oxygen tubes from the departed jumpers and await the second pass. No, don’t even, said one of the organizers with experience in high-altitude exits. Stay on your butt and stay on oxygen until exit time and then go.

But we did exactly the opposite of that and it was a near catastrophe. One of the jumpers picked up a disconnected oxygen line and became hypoxic enough to fall flat on his back right in front of me. Wisely, the ramps were closed up and we rode the airplanes down—all 200 of us—proving once again that something as risky as skydiving requires unrelenting discipline. The challenge of it is often just learning to think straight with a quart of adrenaline gushing through your veins.

As is obvious here, sometimes you can’t.