JNCA-5 chart

Richard

Richard

Final Approach
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Ack...city life
Please provide information on some symbols and Lines of Constant Grid Variation as shown. What are the GN and GV grids and how do I use the Convergence Table shown in the legend at the bottom of the chart?
Also, what are the two letter identifiers shown at 15 degree intervals of both Lat and Long and what are their significance to me? The letters are at the perimeters of the chart (EX: EJ 30*Lat EH)

A light grey symbol shown as either a large cross +, a "T", an upside down "T", an "L", or a backwards "L" at some, but not all, Lat Long intersections (EX: "T" at 109*00'00" 48*00'00").

I have an idea what they may mean but am not sure.
 
Richard said:
Please provide information on some symbols and Lines of Constant Grid Variation as shown. What are the GN and GV grids and how do I use the Convergence Table shown in the legend at the bottom of the chart?
Also, what are the two letter identifiers shown at 15 degree intervals of both Lat and Long and what are their significance to me? The letters are at the perimeters of the chart (EX: EJ 30*Lat EH)

A light grey symbol shown as either a large cross +, a "T", an upside down "T", an "L", or a backwards "L" at some, but not all, Lat Long intersections (EX: "T" at 109*00'00" 48*00'00").

I have an idea what they may mean but am not sure.
Click to expand...

I cant tell you what a star at the top of an airport means...(snicker)
 
Richard said:
Please provide information on some symbols and Lines of Constant Grid Variation as shown. What are the GN and GV grids and how do I use the Convergence Table shown in the legend at the bottom of the chart?
Also, what are the two letter identifiers shown at 15 degree intervals of both Lat and Long and what are their significance to me? The letters are at the perimeters of the chart (EX: EJ 30*Lat EH)

A light grey symbol shown as either a large cross +, a "T", an upside down "T", an "L", or a backwards "L" at some, but not all, Lat Long intersections (EX: "T" at 109*00'00" 48*00'00").

I have an idea what they may mean but am not sure.
Click to expand...

Useless post by me - but I don't even know what a JNCA-5 chart is. If you could point me in the direction to research, I may be able to find your answer.
 
Is it this by any chance?

temp_cae07565Ad276A455cAb403A613605fe87eb.gif
 
Richard said:
Please provide information on some symbols and Lines of Constant Grid Variation as shown. What are the GN and GV grids and how do I use the Convergence Table shown in the legend at the bottom of the chart?
Also, what are the two letter identifiers shown at 15 degree intervals of both Lat and Long and what are their significance to me? The letters are at the perimeters of the chart (EX: EJ 30*Lat EH)

A light grey symbol shown as either a large cross +, a "T", an upside down "T", an "L", or a backwards "L" at some, but not all, Lat Long intersections (EX: "T" at 109*00'00" 48*00'00").

I have an idea what they may mean but am not sure.
Click to expand...

Sounds like you need this:

http://www.naco.faa.gov/ecomp/ProductDetails.aspx?ProductID=USRGD
 
Richard said:
Thanks, Troy. I was at that site and must have skipped right by that particular product. I'm gonna' get me one, I'll look forward to all the cool tidbits it must contain.
Click to expand...

Let us know what you think of it. I'd like to get one if it's worthwhile.
 
Grid nav is a system of navigation used in the polar regions where the convergence of the longitude lines is so severe that normal navigation procedures become too hard to do. The "grid" is a, well, grid of parallel and perpendicular lines laid over the earth to provide a rectilinear, uhh, grid which can be used for heading reference. You spin your DG to "grid north" and then navigate without reference to true or mag north. Grid variation, or "GV," is the variation between grid north (GN) and true (or is it mag? it's been a while since UNT at Mather and we never went to the polar regions in the Tactical Air Forces) north at any given point.
 
Ron Levy said:
Grid nav is a system of navigation used in the polar regions where the convergence of the longitude lines is so severe that normal navigation procedures become too hard to do. The "grid" is a, well, grid of parallel and perpendicular lines laid over the earth to provide a rectilinear, uhh, grid which can be used for heading reference. You spin your DG to "grid north" and then navigate without reference to true or mag north. Grid variation, or "GV," is the variation between grid north (GN) and true (or is it mag? it's been a while since UNT at Mather and we never went to the polar regions in the Tactical Air Forces) north at any given point.
Click to expand...
Well, that makes sense but why does the GV extend all the way south into Mexico, as depicted on the chart? Standardization would be my guess at the answer for that question.
 
Richard said:
Well, that makes sense but why does the GV extend all the way south into Mexico, as depicted on the chart? Standardization would be my guess at the answer for that question.
Click to expand...

My guess would be you are correct. I think the JNCA-1 charts (no longer available?) that cover the Arctic regions would have more use for that feature.
 
Troy Whistman said:
Let us know what you think of it. I'd like to get one if it's worthwhile.
Click to expand...
I just made an online order for this product at faa.gov page. It's a US govt agency and the site is unsecure! It's a huge hassle to set up a secure account--it took me two tries because the faa site sent me to a page which lost my account info. Not only that but they list every country on the planet which include those countries you and I are banned from doing bsiness with or traveling to.

Hopefully, the user's guide arrives and not by black helo and someone doesn't use my 'secure' information.

BTW: I have a debit card issued from my local-owned bank. That account is kept purposely small used only for online purposes. Even so, I change the password after every online purchase.
 
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I received the Aeronautical Chart User's Guide, FAA Product ID: USRGD, today and while I think it a very worthwhile reference it contains squat re: JNAC-5 chart.

Maybe I'll start a thread of factoids about av chart symbols. Here comes a quiz for all levels...
 
Richard said:
I received the Aeronautical Chart User's Guide... it contains squat re: JNAC-5 chart.
Click to expand...

Man, that figures. I feel like I owe you the cost of the book, seeing as I suggested you buy it. I got thinking later, since the JNCA is a DoD chart, you'd probably need a DoD reference guide, not an FAA or NOAA one.

Richard said:
Maybe I'll start a thread of factoids about av chart symbols. Here comes a quiz for all levels...
Click to expand...

Bring on the pop quizzes! Those are fun, keep us learning, keep us sharp.
 
Troy Whistman said:
Man, that figures. I feel like I owe you the cost of the book, seeing as I suggested you buy it. I got thinking later, since the JNCA is a DoD chart, you'd probably need a DoD reference guide, not an FAA or NOAA one.



Bring on the pop quizzes! Those are fun, keep us learning, keep us sharp.
Click to expand...
Troy, you owe me 4 clams. But do I get to keep the book? It is valuable--mostly for the new pilot. CFIs should have it in their library.

How do you figure the JNAC is a DoD product? It is produced by NIMA, Nat'l Imagery and Mapping Agency. I just noticed a small notation at the bottom of the chart which says civilian users should contact NOAA Distribution Branch, Nat'l Ocean Service for NIMA products.
 
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