Why is Lookout Mountain a P3 site?

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dfjon
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Why is Lookout Mountain a P3 site?

Postby dfjon » Fri Aug 05, 2016 3:07 pm

Hi all,
I might visit the area in September again and I've always wanted to know why is the site at Golden possibly dangerous after 11 am? If the wind is from the east, why would there be an issue?

I did a quick sled ride there in the early morning 2 years ago, thanks to Ed observing. But after 11 am and in the afternoon, visiting P2 pilots were discouraged from flying. I'm happy to heed the warnings of this site, but even if I'm a visiting P3 pilot I'd like to understand the mechanics of it. We did not have time for an explanation last time.

Does it have to do with lee side thermals from the west side of the mountain? Or is it that rocks on the eastern side heat up and create strong/punchy/uneven thermals that are more likely to cause collapses? I know there have been some accidents there over the years, I just don't understand why if the wind is from the east.

I'm trying to attach an image of the site, please feel free to draw in lines of where the trouble comes from. Feel free to be as detailed and nerdy as possible, I'd like to understand it thoroughly. Let's assume wind from the east at 6-8 mph.

Thank you,
Dan
ps. If anyone wants to try to fly xc from Boulder to Golden the first week of September, please let me know.
Image

jjhildebrand1
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Re: Why is Lookout Mountain a P3 site?

Postby jjhildebrand1 » Fri Aug 05, 2016 6:09 pm

Dan,
There is a lot that can be discussed here from the perspectives of mechanical turbulence, thermal turbulence, and shear turbulence. To cover all that in context of a dynamic site like Lookout, would take books of information, which would most efficiently be presented via conversation- in fact many many conversations and only to really understand you need to fly often at the site. However, I will take a stab at a very very generic explanation specific to your question of why that when there are east winds (which is an entire different discussion b/c your statement of "east winds" is incredibly simplified when in reality there are at least 2-3 dozen factors/hazards involved with "east winds") in context of why after 11am. Others should chime in here, if so inclined.

Firstly, 11am is just a general rule of thumb and it all depends on the season on day's conditions. 11am in winter is different than 11am in high summer. So, do not use 11am as a hard and fast rule on when conditions are getting out-of-hand, rather it should be how the conditions are developing. Now, onto your question of conditions after your 11am timeframe, or 9am, or 2pm- it's all relative per my above comment.
Very generally speaking, thermic conditions develop (get stronger) throughout the day (from dawn) until peak soil heating occurs at around 2-3pm (assuming no atmospheric interference, such as clouds). The sun’s maximum zenith is noon, but soil sorption of the sun’s shortwave radiation lags by 2-3 hours. Thereafter, thermal conditions begin their path toward weakening, although very strong conditions can, and often do, persist until the early evening- so again, it's all relative on that day's conditions. During that timeframe of mid to late morning and mid to late afternoon, thermal strength increases, often times dramatically at locations like Lookout. With increased thermal strength and maturity, thermal turbulence generally linearly increases (barring other factors such as inversions, caps, wind shear, etc… again, another conversation). For newer pilots, and the old dogs alike, conditions can surpass the skills of the pilot leading to dangerous flight configurations.

The "east" wind you mention is a completely separate matter (upslope induced flow regime on the lee side of a mountain range) than why it's discouraged for newer pilots to fly mid-day conditions at Lookout and in fact at every other thermic site out there. So, what I've talked about here deals with the thermal turbulence part of the equation. Lookout, given its aspect, altitude, setup to local flow patterns, and physical makeup, often yields outstandingly dynamic conditions that can quickly become challenging for any pilot. That is why there is a 10-flight sponsorship program, which helps pilots start their journey to understanding the site. While construction in the LZ is occurring (check other forum postings), the sponsorship program has been put on-hold, for safety reasons.

Hope that helps, a bit.
, ) jake

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Mike Jobin
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Re: Why is Lookout Mountain a P3 site?

Postby Mike Jobin » Fri Aug 05, 2016 8:57 pm

Hi Dan,

This is a good question that most P2 pilots will ask about... Yes there is a big issue with lee side conditions, if you've had the unlucky opportunity to get stuck in rotor somewhere you would notice super strong (small) thermals with hard edges that cause collapses. When you think about it, Lookout is a lee side site in a larger scale. So at lookout, the expectation is strong(small) thermals with sharp edges that cause collapses if you don't have the experience to prevent that kind of thing. And when you add the monsoon flow of weather, you REALLY START TO GET YOURSELF INTO TROUBLE QUICK.

Now I am just really talking about the front range. Lookout specifically has issues that make it a P3 site: Restricted landing field ( which is now mostly a no go). Not only that, the LZ's we have are VERY active with thermals. And as soon as the clouds build up, it is so hard to get down... that requires a lot of skill. It is very common to struggle for 10 or 20 mins to get down when the clouds build up. There are many more issues with the site to be aware of, only to be learned by experience really (compression, side hill rotor, venturi, sheer layers, inversion, mixing layers, outflow). Maybe at this point it is redundant to say that lookout is a complicated site.

If that doesn't hit home, there was one day that I flew (around 2 pm) and had 1800 ft. min. lift right off of launch. The next day at the same time of day, my friend (very experienced pilot with 20+ years experience) died from not being able to recover from complications during similar conditions.

We do want more pilots to be able to fly here and learn from the shared experience of lookout. It has to be understood that lookout is a tough place to fly and really it is sad to say that it is also one of the most dangerous sites in the US (statistically). On the other side, if you can learn this place you can fly anywhere and do well. When I fly lookout, it is rare that I get less than an hour flight usually 2-3 hours because I choose good days. It is important to understand it all that is why we are so reluctant to take responsibility for new pilots.

Jobin

dfjon
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Re: Why is Lookout Mountain a P3 site?

Postby dfjon » Fri Aug 05, 2016 9:51 pm

Thank you both for the thorough answers. Sounds like the reasons are complicated. But in a nutshell, small and sharp thermals sound like the main reason, as well as interference from lee side thermals if you drift a little west over the peak.

I was planning to fly from Boulder and wanted to be prepared in case I was able to reach Golden by late afternoon. But it sounds like the LZ won't be open by then anyway so maybe I'll try a northern xc flight from Boulder.

I'll make a separate post to invite others to fly with me at Boulder. I hope you guys can join me, it would be cool to fly with 2-3 others. It will most likely be the first week of September.

Mike, I am sorry about your friend. I believe I read the news about that.
Dan


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