[Home] to paraglide.net [SD Log] [Amigo] [Activity] [Photo] [Comments] [Incidents] [Weather] [SBSA] [SCPA]
Burce Wallace / Overmatched and Out of Control... (incident)
Comment (by sd)
On 8/23/01, Bruce Wallace deployed his reserve canopy. He had lost control of his aircraft near the top of a thermal and entered a series of cascading trouble. He attempted to get the aircraft under control and wisely elected to use his reserve prior to hitting the ground. Below is Tom's reply to Bruce's posting.
Bruce,
I would need more info to comment on the initial gyration, but it seems distant and not directly related to your need to deploy. From your article, it appears your decision to deploy was a good one. A more experienced pilot might have been able to clear the cravat in the available time remaining, but your were clearly overmatched and survived to fly another day.
Your incident requires in-depth discussion of basic advanced canopy control principles, but briefly:
If the canopy gets below the horizon without a centrifugal load, the lines will go slack as you fall through. If your lines go slack, you have enabled one of the ingredients for a caveat, which you encountered. When the wing cravats, you have a lot of drag on one side. The asymmetric drag can result in a spiral or sometimes a spin. Since the drag is proportional to the square of the airspeed, a spiral dive can accelerate exponentially if you don’t arrest it immediately.
You should get your aircraft under control prior to clearing cravats and tucks (a full stall is a controlled maneuver).
You clear a cravat by unloading the lines and shaking the canopy. If it’s a small one out near the tip, you can deflate one side by pulling on the “A” riser (1/2 big ears). If it’s inboard you need to full stall the canopy and let it shake out, then recover from the stall.
When flying in active air, angle of attack is the most important parameter to control. You may want to read some of the articles in my comments section on paraglide.net http://paraglide.net/comment relating to angle of attack. I’ve learned the hard way that you need to avoid getting the canopy below you at all cost. On occasion, this may require aggressive breaking with a lot of muscle (50 lbs + per side??). I also recommend watching Jocky’s video, “Security in Flight”, numerous times over the course of a season. (please buy a legal copy to support the production of additional material)
You also need to do more than understand the dynamics academically. You lost control of the canopy, and rather than dampen the gyrations, your control input timing aggravated the oscillation to the point of almost getting shrink wrapped. Practice your maneuvers, starting with mild fore and aft surges and working up to more advanced stuff. You have to build an automatic intuitive response. I learned most of my stuff through OJT, but didn’t always work it out before hitting the ground.
For confirmation, there are a couple of things in your article that don’t add up. For example, you said that your entered a spiral to the left with a cravat on the outside of the spiral. I think you were probably overloaded and your recollection may be distorted.
Tom Truax
Bruce's Article, posted on the SCPA flight discussion for 8/23/01:
by Bruce Wallace (aka GeneJock)
Had an interesting flight today off Chief Peak that ended in my deploying my reserve parachute. Since I suspect that few of the pilots reading this post have been in this sort of a pickle or have thrown their reserves, I will describe it in as much detail as I can remember with the hope that more experienced pilots will comment and we can all learn from my adventure. My wing is a Nova Carbon (small) and, when fully loaded, I am near the top of the weight range. Some of the data I will be discussing here came off the barograph trace of my variometer, which was recording at five second intervals.
Chief had been active today and after a bit more than an hour in the air I decided to fly home. I found 400 up above the last bump before Twin Peaks and decided to add some security altitude before heading out across the valley. After a couple of turns I was at 850 feet AGL when things went haywire.
My (left) turns suddenly tightened and, though I was still going up, I wondered if I had spun the wing. However, I was still banked and felt G forces from the turn and concluded (perhaps incorrectly given that my inside brake was at about shoulder height?) that I had entered some kind of vortex rather than having spun the wing. I let up on the inside brake to exit the situation and the inside wing collapsed. I pumped it out and the outside wing collapsed and crevatted. I pumped that out and the wing went into a series of very violent wing overs while heading down (at least one to each side -- possibly more, I cannot remember). I believe that I then pulled both brakes to about shoulder height (with one wrap) to try to stabilize things. The wing surged far forward (about 30 degrees below me) and to the outside. My wing manual said that this is consistent with having been in a spin. I, of course, fell relatively straight down missing the wing by about 10 feet. As I fell, the outside (right) tip folded about 40 percent under and tucked through the lines which were then loose. As my fall snapped the lines taut, the folded tip was trapped in a cravat that I figured would not come out. I then entered a spiral to the left (with the cravat on the outside of the spiral) and decided to toss silk.
According to my barograph trace, I reached a maximum downward velocity of 1900 feet per minute in about 35 seconds -- the reserve then started to slow my descent - at about 500 feet below my last high point and about 350 feet above the ground. I tried to pull in the tangled wing as a best I could in the 25 seconds before I landed safely in the brush.
A passing private plane saw my wing spread across the bushes and must have called the rescue chopper because it showed up just as I was about to reach the trail which would have taken me to Twin Peaks and a better trail down to Thacher. Not being proud (or able to communicate with them), I let them pick me up and drop me off in a field near home.
Experienced pilots -- can you offer insight into what happened here, what I should have done differently, and so on? In the meantime, though this is not an experience that I would recommend all pilots ought to have, it is probably more interesting than jury duty which I have tomorrow morning
'