velvetjo

About 6 months layoff for me after ACL replacement surgery. I had the hamstring graft, sound like it depends on which graft you get for what the docs like you to do when. Anytime somebody tells you they're going to drill a hole in your bones, pay attention - it's gonna hurt for a while. Good luck with your recovery.

Lance

Any chance we could just append this thread to one of the many pay-for-training threads on flightinfo.com?

Lance

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How does that work in the scenario of a person jumping off the high diving board? You feel the “falling sensation” due to what?

Yeah, I'd think that a high dive would be similar to a balloon jump for lack of postural cues - no relative wind force. I'm not sure how fear vs. acclimitization works into the equation, but it sure makes sense that they'd be factors too.

Lance

Here's a stab at an answer from another perspective. I got my instrument rating last year, and the FAA's Instrument Flying Handbook does a pretty good job of describing how & why we experience spatial disorientation in instrument conditions. Some of the concepts seem to apply here too. Sorry in advance if I screw any of this up, it's from memory.

First, the body maintains spatial orientation in 3 ways: vestibular, postural and visual. Vestibular orientation refers to the semicircular canals in the inner ear, which sense the movement of fluid and interpret it as turning movement in 3 separate axes. Postural orientation is the interpretation by the brain of forces felt on muscles, joints, and skeletal structure. Visual orientation is the brain's interpretation of a visual image.

When these 3 senses disagree with one another, it's a trigger for spatial [dis]orientation, and some can be fooled easier than others. An example is an extended turn and/or altitude change in clouds initiated very slowly, so that the vestibular and postural cues indicate straight & level flight but the airplane is actually turning and/or climbing or descending. This is basically how a graveyard spiral occurs. There are several other examples of similar spatial disorientation illusions, but the important idea is that all of these types of orientation come into play.

So based on all of that, my guess is that the absence of forward throw from the aircraft in balloon jumps, etc., may cause some people to have the dropping feeling due to the lack of postural cues (relative wind pressure in this case). I'd also guess that during a normal jump, all 3 senses tend to agree on the same orientation, which suppresses the dropping feeling.

Any thoughts?

Lance

Thanks for the help, everyone. That photo & video helped a lot for climbout. Hoping to get one today.

Lance

Does anyone here have experience jumping from powered parachutes? I have a chance to get a ride in one soon, and the pilot has agreed to let me jump from it.

We'll have permission of the landowner (at a private airfield), and I know how to call ATC for the jump NOTAM. I plan to rehearse the exit several times on the ground with the pilot. Any other concerns? Climbout advice? Does the pilot need an emergency chute?

Lance