el_chester 4 #1 February 9, 2009 Yesterday I jumped in a 3-way belly group, followed by a 3-way freefly group. The lower winds were very light - could be considered calm. I don't know what the uppers were doing. The freeflyer group after us say they gave us at least 6 seconds separation out of the skyvan. Come pull time, I am starting to track, and to my surprise, about 600 (?) feet lower, and in front of me, right in my tracking path, tracking in the same direction as me (90 degrees from jumprun) is a guy waving off, dumping and soon after his inflating canopy. So I evaluated opening right there and then, but opted to change my track direction and avoid the opening canopy. Then I pulled making sure I'd be open below him. When his canopy finished opening it started flying towards me, so having ensured the vertical separation was a good thing. I think he must have been surprised when he saw me so close! (maybe 150 feet horizontal, 100 feet vertical separation when I was open). On the ground I had a very civilized discussion with all three freeflyers in his group, and they agreed that they should have left more separation, but were also surprised at the outcome. I am still not quite sure how the drifting in freefall happened that I ended overtop of him. Any ideas? I believe that the incidents forum is responsible for the good outcome here. My awareness level to immediately look for people and canopies below me during trackoff is probably higher than most people's - and I owe that not only to bigways, but also to reading about incidents and near misses, as well as the endless discussions about exit order and separation. So a collective thanks to all of you who contribute to dropzone.com! Cheers. -- Be careful giving advice. Wise men don't need it, and fools won't heed it. Quote Share this post Link to post Share on other sites
davelepka 4 #2 February 9, 2009 QuoteI am still not quite sure how the drifting in freefall happened that I ended overtop of him. Any ideas? Chances are that he ended up under you as opposed to you ending up on top of him. The freeflyers fall faster than than you. Let's say your belly group is doing 110 or 115 mph, and the freeflyers are doing 150mph. Six seconds of seperation equals about 600 or 700ft vertically, so I'll leave you to do the math, but as you can see, the freefly group will overtake your group at some point in the skydive. Add to this the fact that the higher airspeeds of freeflying allow higher horizontal speeds as well. A little backslide on your belly might be a walking pace, while a little backslide in freeflying could be two or three times that speed. Again, figure out the jumprun speed of the Skyvan, and how far it traveled in six seconds, and you'll see that it's just a couple hundred feet. Over the course of 45 seconds of freefall, you can see how easy it would be to backslide your way rght through that seperation. Finally, head down freeflyers have break off manuver they can do where they go from facing in towards their group into an intentional backslide, which they just continue the rotation into a track. The result is a very smooth transition from head down to a track, where they enter the track with all the the speed from head down and flat out haul ass away from their group (possibly right towards another group, possbily right under another group if they managed to fall faster than that group). That's my guess. Edit - As fas as your part in this goes, maybe next time try to track off the jump run as opposed to up/down the jumprun. With only three in your group, there's plenty of sky for everyone to track well clear of jumprun. Quote Share this post Link to post Share on other sites
Reginald 0 #3 February 9, 2009 QuoteI don't know what the uppers were doing. There is part of your problem. So why were you and the other group using timed separation if you didn't know one of the most important variables in calculating it?"We've been looking for the enemy for some time now. We've finally found him. We're surrounded. That simplifies things." CP Quote Share this post Link to post Share on other sites
billvon 2,384 #4 February 9, 2009 Another story from a few weeks back: I was doing video for a 4 way team. Through a series of unlikely events, the exit order became: 1) disabled tandem (needed to be near the door) 2) freefly group "filming" the tandem but not exiting with them 3) solo 4) our 4-way I talked the solo into going after us, but the freefly group was adamant that they wanted to video the tandem's exit and exit right after her (but not come near her in freefall.) OK, then. Since I was the first out after them I was just going to wait a long, long time. A freeflyer further back in the plane saw this and began to get agitated. "That's DUMB! Tell them to move back here!" she yelled at me. "I tried; you can try if you want," I told her. She then began yelling about exit separations and how all this was totally unsafe. I was tempted to tell her that it's only unsafe if you don't leave enough time (which is a _lot_ of time in that situation) but by then someone else was arguing with her. On exit, the tandem went, then the freeflyers. I stuck my head out the door and started counting on my fingers (in case anyone was wondering what I was doing.) I got to 3 before someone started screaming "GO!" (Needless to say it was the freeflyer who had been arguing about the exit order.) Climbed out at 10 and took my time. Total delay was about 18 seconds, which was plenty for this moderate-wind day. On opening I saw them a few hundred feet from us downwind. This time it wasn't the Incidents forum but rather all the talks we've been having about exit order that came to mind while I was in the plane. As always it's good to think about stuff like that _before_ you need to use it in real life. Quote Share this post Link to post Share on other sites
erikph 0 #5 February 9, 2009 Video from a jump last year. Exit separation was 25 sec. A solo freeflyer ended up underneath me. He exits, followed by three other solo (6 sec separation), then us. 25 sec after him. It was an instruction jump, an AFF level 6, so we were moving about a bit. But not that much, all the others were where I expected them to be under canopy. Normal condotions, 25 sec delay, and yet... http://www.youtube.com/watch?v=XEgFw4CJBVMblue skies, http://myjumps.blogspot.com/ Quote Share this post Link to post Share on other sites
rehmwa 2 #6 February 9, 2009 Quote.....but by then someone else was arguing with her...... ........I got to 3 before someone started screaming "GO!" (Needless to say it was the freeflyer who had been arguing about the exit order.) ........ I laughed aloud at both these statements - it's so typical. Good for you for dealing correctly with both the people in front of you and the people behind you who didn't 'really' get it. ... Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants Quote Share this post Link to post Share on other sites
Scrumpot 1 #7 February 9, 2009 Quote On exit, the tandem went, then the freeflyers. I stuck my head out the door and started counting on my fingers (in case anyone was wondering what I was doing.) I got to 3 before someone started screaming "GO!" (Needless to say it was the freeflyer who had been arguing about the exit order.) You give way too much courtesy Bill, in these situations. My counting on my fingers deliberately would have turned into then folding my fingers VERY DELIBERATELY into the digital salute. ...All of course while I still kept counting, naturally! coitus non circum - Moab Stone Quote Share this post Link to post Share on other sites
el_chester 4 #8 February 10, 2009 Firstly: you are right - I never assigned blame solely to them. However, if you go by everything we've learned here, if a group of freeflyers leaves after a group of belly fliers, and leaves a reasonable separation, with their extra "throw" during the first seconds of freefall, that separation should increase. It would take a hell of an upper wind to elliminate this separation (try it out yourself with John Kallend's model here.). So surely this had to do with the way the group(s) flew towards each other along the jumprun line. And this is where it gets scary... because you cannot control every person in the plane and how they will fly. Hence an added awareness (/paranoia) is not a bad thing during trackoff. And that added awareness, in my case, comes from reading here, and knowing that there WILL be dangers out there, some of them out of your control. -- Be careful giving advice. Wise men don't need it, and fools won't heed it. Quote Share this post Link to post Share on other sites
el_chester 4 #9 February 10, 2009 QuoteEdit - As fas as your part in this goes, maybe next time try to track off the jump run as opposed to up/down the jumprun. With only three in your group, there's plenty of sky for everyone to track well clear of jumprun. As I stated in my original post, both him and me tracked off in a direction away from jumprun, which indicates that after being in freefall for a certain amount of seconds longer than their group, we ended up sharing roughly the same column of air. Given that we were first and belly, and they were second and freeflying, the only explanation I can come up for this to happen is if either or both groups didn't fall on their column of air and flew a significant distance along the jumprun towards the other group. I don't think that winds alone could have put one group overtop of the other. Try it out yourself with John Kallend's model. I was watching other loads and separation between groups had been and continued to be good. Our group I'm quite certain didn't slide over towards theirs, and I did not ask them whether it could have been them. I don't know if they were sitflying, head down, or their experience level. -- Be careful giving advice. Wise men don't need it, and fools won't heed it. Quote Share this post Link to post Share on other sites
