Yellow "Congested" areas on the Sectional chart.

[UndauntedFlyer]

I have always been of the impression that the yellow areas on the Sectional Chart were congested areas. That makes sense even though I'm sure there are other areas that would be called congested that are not in yellow.

My question concerns a person who recently told me the yellow marked areas are areas that are simply areas that show up as lighted areas from a mapping satellite at night. So if you went into the middle of sparsely populated acreage and lit it up like a Las Vegas but no buildings or people, then it would be shown as yellow on the chart.

This may be true; does anyone have any documentation of this one way or the other? What doe the yellow really show?

 

[CA1900]

I have always been of the impression that the yellow areas on the Sectional Chart were congested areas....

My question concerns a person who recently told me the yellow marked areas are areas that are simply areas that show up as lighted areas from a mapping satellite at night....

This may be true; does anyone have any documentation of this one way or the other?

I've heard the same thing, but can find no documentation to support that.

However, the Aeronautical Chart User's Guide says they're populated places. (Second document on the link, page 20.)

 

[TWA]

I think that they make the assumption that lights = people, and vice versa. But that being said, I've heard the same thing, that they're there to be used as VFR landmarks at night. No documentation though.

 

[340drvr]

Can't find the published reference either, but two examples supporting the "lighted area" definition are both on the Klamath Falls sectional (I'm sure there's plenty of others as well), one just south of Sunriver, Oregon, S21, and another a few nm north of Winnemucca, WMC. Big yellow areas depicted, but certainly no great concentrations of population.

 

[A Squared]

I have always been of the impression that the yellow areas on the Sectional Chart were congested areas. That makes sense even though I'm sure there are other areas that would be called congested that are not in yellow.

My question concerns a person who recently told me the yellow marked areas are areas that are simply areas that show up as lighted areas from a mapping satellite at night. So if you went into the middle of sparsely populated acreage and lit it up like a Las Vegas but no buildings or people, then it would be shown as yellow on the chart.

This may be true; does anyone have any documentation of this one way or the other? What doe the yellow really show?

Well, I don't have an answer to your question, I've heard the same thing myself, but you hear a lot of things. Not all of them are correct.

However, on a not entirely unrelated topic:

Don't asume that the "congested area" mentioned in 91.119 (minimum altitudes) has *any* connectin to the yellow areas on a sectional. There's a CHief COunsel interpretation addressing the concept (or maybe it was a NTSB decision) and essentially, it said that "congested area" from an enforcement perspective was determined on a case by case basis, but that 2 or 3 buildings in relatively close proximity to each other could be considered "congested"

I mention this because I have heard pilots state that if it's not tyellow on a sectional, it's not congested for the purposes of 91.119 (which admitedly has a certain appealing logic to it) but nothing could be further than the truth.

 

[Hugh Johnson]

I found this. Looks to be from the government.

http://virtualskies.arc.nasa.gov/navigation/tutorial/tutorial7.html

 

[Hugh Johnson]

From the horses mouth. Very straight forward.

The "yellow" area on the charts is supposed to correspond to developed urbanized areas. The only significant change regarding charting in these "yellow" areas involves the depiction of obstructions. Generally, obstructions 201' and higher above the ground are depicted on the charts. However in these "yellow" areas, only obstructions 300' and higher above the ground are depicted.

Sincerely,
Rick Fecht
National Aeronautical Charting Office
Visual Chart Branch
301-713-2953 Ext-126"

 

[WestHouston]

Haha. Oh man. The only checkride I ever failed was on my commercial ride. The examiner said I "went below 1000' AGL over a congested area" while doing 8's on pylons. On the terminal chart, there wasn't any yellow for miles. (At the time) I was under the same impression about the yellow being the "congested" areas. So when I questioned the examiner on what the hell is considered a congested area, he told me "there isn't really a specific definition, however an ""aviation attorney" told me that it if there are 3 dwellings or more per square mile, it is considered congested".

I have since told people this and they immediately raise tons of questions, i.e. where are the boundaries, what is considered a dwelling, etc., but I have no answers. I'll tell you one thing though, when I teach my students to do 8's on, we are out in the freaking boonies...

 

[UndauntedFlyer]

From the horses mouth. Very straight forward.

The "yellow" area on the charts is supposed to correspond to developed urbanized areas. The only significant change regarding charting in these "yellow" areas involves the depiction of obstructions. Generally, obstructions 201' and higher above the ground are depicted on the charts. However in these "yellow" areas, only obstructions 300' and higher above the ground are depicted.

Sincerely,
Rick Fecht
National Aeronautical Charting Office
Visual Chart Branch
301-713-2953 Ext-126"

Thank you for this information. This is what we all thought was true about the yellow areas. But the questions till remains, does the yellow have anything to do with urban lighting as would be seen from a maping photograph for charting purposes?