AOA For Dummies Part 2: Real World
Second installment of Angle of Attack video education for wingsuit BASE jumpers
I have noticed over the last couple of years that a lot of really great skydivers seem to have become lazy about exits. It is as if they have collectively decided: ‘We’re good enough to get there fast anyway - so we don’t need to stress about the exit’.
They early divers know they can get to the formation pretty quickly. The medium divers are pretty fast - and they’re not at the back of the plane anyway, so they won’t be last. The last divers are smoking fast - and they love a good dive.
They’re right in one way; They are great flyers, great divers, and the formations still build pretty quickly. I think they’re missing the point though. Last year for example I went to a serious 3-plane sequential event. We made some great complex jumps - but a bunch of them were just a few seconds away from the third point. We all wanted those third points.
To get the third points, we need to find some more seconds. I picked a random jump to look at the timing.
We could definitely have shaved a few seconds off the transition from the first to the second point. Realistically though - the big opportunity would be in getting to the first point faster. Our exit took at least 7 seconds - more than enough time to slowly shuffle the length of an Otter.
For the last divers in a big exit, every second delay at the door adds about 50m of vertical separation (approximate speed at terminal velocity) and about 40m of horizontal separation. A head down skydiver would take about 2.5 seconds to catch up that vertical separation. A classic diver will take significantly longer (they're not quite head-down and they have to catch up horizontally too!) The longer the exit is, the closer the base gets to terminal velocity, and the higher the cost of another 1 second delay. One rule of thumb says that saving 1 second in the door will give you about extra 5 seconds in the skydive, due to a faster first point build.
In our case, getting out 25% faster seems very achievable. Taking a simple ratio on the time to build the first point (this is a conservative estimate), that might save 10 to 13 seconds on the build. More than enough time to get the third point.
I have some suggestions for organisers on practical ways to speed up those exits.
1) Make someone responsible in each plane. That person should ask after every jump how the lineup was, and work to resolve any issues.
At this event, there was no plane captain, and nobody was really stressing about the exits. After the event, I heard some of those late divers talking about the lineup being weak - but nobody wanted to step forward and be the person who complains. Don’t assume that skilled jumpers will make this happen!
2) Brief and practice the exit in the mock-up until it's tight.We always talk about moving on the 'set' in aircraft with a C of G line but the timing is usually off. Drilling it on the ground until correct can make a big difference in the air. Taking the lineup seriously on otter mockups sets an expectation for the sky.
3) Talk about exits during the debrief. Use the video to spot obvious gaps between exiting jumpers.
4) Remind people that the whole plane is responsible for the exit. You might have an easy job as an early diver, but if you can use less space and get out a little faster - then you give precious time to the folks at the back of the plane.
I once flew with Larry Henderson as my plane captain. After each exit, he would ask each jumper ‘Did you touch the feet of the person in front of you as you exited?’. It really set the expectation of how close we could be.
5) If you’re in a trail plane, consider squeezing the first row all the way out. Gordon Hodgkinson showed me this trick. If you haven’t jammed people tight on the outside, then the first row of divers can take the time while they’re waiting for the exit to squirm themselves all the way out just like floaters. As they move out - the second row can move closer and everyone moves up. Effectively, you’re making use of the time during the count to get more people out floating.
6) If it's critical, measure it. I'd love to see how quickly exits improved if we put cameras on the door and per-plane exit times on a whiteboard!
7) Learn from the masters. By necessity, those DC3 folks really knew how to get a fast exit (see video). We have bigger doors and smaller planes. We should use those to be faster - not lazier.