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Cactus521

How much is unlimited visibility in real life

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helloaccording to the thread I posted a few days ago and now is quite too long (http://ftp.avsim.com/dcforum/DCForumID8/20023.html), one of the poster mentioned about an interesting aspect of unlimit visibility in FS that it is not correctly depicted. In reallity how far could a pilot really see in the weather catagorized as "unlimit visibility"? So I could set the limit in FS accordingly.

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By the end of February I flew from Lisbon to Munich . When I was over the Alps I could see the mountain ranges to an incredible distance. Later I learned that the visibility at that time was over 100km (over 60 miles).

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I have seen Alaskan weather reports show horizontal visibilities over 100 miles in good clear conditions (where the observer has a mark at that distance ... ie: mountain) I think they are kind of discouraged from doing that now, but 60 miles is common.edit:... because they are supposed to be reporting "average" visibility and should have markers in all directions, not just one.In real life, "unlimited" USED to mean "more than 15 miles", and observers were more-or-less obliged to report a definitive visibility below that. Only sites with actual markers at greater distances could report actual distances above 15, (such as Alaskans who could see distant mountain peaks).With the conversion to reporting by METAR a few years ago, that limit seems to have dropped to 6 miles, and many sites now simply report "more than 6 miles" (coded as: P6SM). I don't know how the internals of FS2002 manage that in terms of the actual display.Art.

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Look up. See the stars from cockpit ? what about some millions of lightyears ?Sorry, couldn't help it :-lolIf I understand your question you'll find the answer here http://www.boatsafe.com/tools/horizon.htmIt has to be corrected by the atmospheric refraction (I guess)Dominique

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5 miles in the UK is not uncommom. Above 12,000 feet 60 miles and beyond.Having flown Cessna 310's, you would be suprised how close you are before the field comes into clear view.AD

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I have seen some amazing visibilities in the southwest, and in California. Within moments of takeoff in California out of SFO, it was not uncommon to see Mount Shasta almost 150NM to the North... On many days, especially if my flights were scheduled after a winter storm, I could see well into the great basin beyond the Sierras once we cleared 10,000 ft...which was approx. over Concord, CA, some 150NM from the beginning of the great basin.In Arizona, the within a couple of moments from Sky Harbor takeoff, I can see the San Francisco Peaks north of Flagstaff, some 100+NM away. Because our weather is normally dry, this is the usual vis., except during monsoon season, when we can get dewpoints between 60 and 70F.At night returning from BWI, one pilot reported the lights of Phoenix approx. 180NM out. To date, I think that is the best vis. I've heard reported. I know I have often seen the lights of Vegas as I've flown from SLC to Phoenix. That path passes Vegas approx. 100NM east, give or take.So, the person who said in the other thread that "the real world doesn't look like that" hasn't done much flying, or at least not in the right places. From 1966 (my first flight) to present, I have logged over one million miles on four continents. Now, having said all that, there's a difference between the "best" and the "norm".Move out of the dry and arid states, and into the more humid states, and visibilities drop quite a bit. This is even more true in the summer, as the hot and steamy weather settles in east of the Rockies. At times, flying over the south in "clear" weather, I've been challenged to see beyond 10-20 miles at FL350. That leads to something I like to call FS2002's "accidental realism". In the midwest and south, it almost a given to see "patches" of ground become blurred while flying in clear weather. I'd say I see this on average, every thirty to sixty seconds flying in this region. I don't know the reason it happens, but I suspect it has to do with varying humidity factors. The "dynamic blurring" of FS simulates this amazingly well, but I doubt it's by design.I should conclude this by saying that, below 10,000 ft. and in urban areas, I often see too much smog to see beyond 10-20 miles, unless looking almost straight out for elevations higher than my own. There's so many factors that determine vis... The fact that we can look up through 60 miles of atmosphere on a clear night, and see the moon, yet we can't see a mountain ten miles away at the same moment, just leads one to conclude that the dynamics of all this are very complex. -John

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