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Slope Comfort Zone??

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Re: Slope Comfort Zone??

Postby rlown » Fri Mar 19, 2010 12:47 pm

Is there a map of known aircraft crash sites that you're indexing against? It would be interesting to see, only because one can descern from the predicted flight path of the plane, how maybe it ended up there, based on weather, pilot control, etc. In general, unless a plane glided in to an almost level river area under a pilot's control, there would be little left to see from the air, unless it struck tinder, and someone saw smoke. After a few months, or years, it would be hard to find.

I know, not so much about slope for search, but a pilot doesn't really care about slope until his engine dies over the Sierra and he cant see the darned terrain.



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Re: Slope Comfort Zone??

Postby Shawn » Fri Mar 19, 2010 10:41 pm

Mike -

Good info. I've been up there a few times (Sphinx and Palmer) since speaking to Jordan. While I certainly wasn't in the area to look for aircraft, when I passed thru the areas I sure recalled my talks with him and looked up (or down) at the more difficult terrain with a totally different view of things.

George -

I would think that map, marked up as you say during the spring training, would be a prized possession with all of that experince on hand noting the "path less traveled" all at one time.
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Re: Slope Comfort Zone??

Postby giantbrookie » Sat Mar 20, 2010 11:00 am

George, from my experience the slope-degree of difficulty relationship is somewhat dependent on the smaller order topographic details that are below the resolution of standard DEMS (although certainly within the realm of Lidar). What goes as class 3 plus is less steep than most imagine and one must be careful over what length of slope one averages. If you measure a lot of slope angles, say averaged over 100 feet or so, you find that the transition from a broken talus slope to a full blown cliff is actually at about 40 degrees even if the average human mind sees "cliff" at about 60 degrees. This actually has to do with the angle of repose of rock (based on the "friction angle" for sliding on fractures--this tends to be in the 35-40 degree range for "good" rock). For example the legendary Willis Wall on Mt. Rainier, which is mixed technical snow, ice, and rock, with a top end rock pitch of about 5.7 has an average angle of about 45 degrees. Some slopes at about 40 degrees have nicely spaced big benches and come out as class 2. The highest angle class 2 (by my reckoning) slopes I've seen are the exit stage right chutes off of the NE couloir of Abbot (rated 3rd class, but seemingly just steep 2--grade inflation in my estimation--I'd rate only the top knife edge moves on this route class 3) and the usual "staircase gully" ascent route of Tower Peak (long time historical rating of 3rd class but I just didn't see it--It was indeed a staircase with very wide benches). These have a very steep average angle but really big benches, so that a human's risk of fall and likely fall distance is minimal (hence the my verdict of steep class 2). Neither of these reaches really required hand-over-hand climbing owing to the very generous benches. Although amazingly steep, for class 2, I doubt if the average slope angle for these reaches is much above 40 degrees, though (if indeed it is). Where one transitions from class 3 to 4 plus is much trickier. Certainly if one is up at 60 degrees average over a hundred plus feet I think it will generally be safe to say that one is above 3rd class, but, as noted below one can get well above 3rd class at much lower slope angles down below 40 degrees. It just takes one small headwall or step beyond one's reach (with some air) to take an otherwise class 3 and raise it a notch or two. Also, on exposed featureless granite slabs, the rating can go to class 5 (think Starr King) at average slope angles that may be below 40 degrees. Bottom line is that a slope map can give a rough impression of climbing difficulty, but there will be lots of 35-40 degree terrain that will play much tougher than its average slope angle.
Since my fishing (etc.) website is still down, you can be distracted by geology stuff at: http://www.fresnostate.edu/csm/ees/facu ... ayshi.html
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Re: Slope Comfort Zone??

Postby paul » Mon Mar 22, 2010 1:38 pm

I think one other factor in trying to guess where people don't go is to consider destinations. People most often go to peaks, passes, lakes and meadows. Anywhere on the way to any of those is likely to have been traveled. Corridors have been mentioned already: streams and ridges tend to be the natural corridors where there are no trails. So there is considerable area that is not on the way to anywhere, and is not a destination on its own, that has a high likelihood of having never been trod upon. And the areas that meet those criteria and have thick brush are even more likely to be untrodden, and also have good potential for hiding wreckage.
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Re: Slope Comfort Zone??

Postby gdurkee » Tue Mar 23, 2010 2:16 pm

As the discussion continues here, I would really love to do a multi-year tracklog dump to see exactly where some people do go. Russ' suggestions elsewhere on using Google Earth are one possibility. I'm still pretty convinced that above, say, 8,500 most all terrain is covered over 10 to 20 years. Good arguments here that in forested/brushy country that may not be true, though looking at a map, there's darned few forested areas that I don't think get at least some occasional traffic through it. If we could just get the dope growers in the brushy Mineral King area to report any wrecks they've discovered... . They have undoubtedly covered every inch of that terrain.

I just started an email exchange with some UAV nerdlings with DARPA. I'm hopeful one can show up at our GIS/SAR workshop. If not, I might run some of these ideas by them and see what possibilities exist for remote sensing of terrain and strategies they might suggest for finding stuff.

Incidentally, there is a "crash map" for the US and California. The accuracy isn't great. I tried to look at it with a view to type of aircraft, where they go down (by elevation) and any clusters that jump out, but it would take a better statistical brain than mine to make sense of it. Interesting though. Basically anything with an elevation of greater than 1 foot is a hazard. It's like there's this bathtub ring of wrecks around the Central Valley.

thanks for the continued thoughts.

g.
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