Notam and TFR plotting errors (?)

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Brad W

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Is this a plotting error or do these airspace restrictions really not track with the overlaying airspace?
Just browsing https://www.1800wxbrief.com/Website/interactiveMap and noticed this NOTAM for an airshow coming up in a couple days

It's not shown to be concentric with the airport's class D
This TFR is defined as a 5NM radius based on a point defined on a radial from the CRG VOR
As a standard class D airspace is a little less than 5nm radius so I suppose KNIP is probably non-standard so that would explain it being slightly smaller
But why not just define the TFR based on the Class D...or at least the class D's center point?
(seems like it would just be easier and generally safer to NOTAM the KNIP airspace but up to the higher altitude)
OR
Is it?...and this is just sloppy plotting error?

I've noticed this before with TFR's so I've been curious about the logic or lack thereof for a while now.

upload_2022-10-20_8-21-58.png

on skyvector it looks like this...pretty much the same
upload_2022-10-20_8-25-38.png
 
the NOTAM:
FL..AIRSPACE JACKSONVILLE, FL..TEMPORARY FLIGHT RESTRICTION. PURSUANT TO 14 CFR SECTION 91.145, MANAGEMENT OF ACFT OPS IN THE VICINITY OF AERIAL DEMONSTRATIONS AND MAJOR SPORTING EVENTS, ACFT OPS ARE PROHIBITED WI AN AREA DEFINED AS 5NM RADIUS OF 301402N0814022W (CRG236010.5) SFC-15000FT UNLESS AUTH BY ATC. EFFECTIVE 2210201600 UTC UNTIL 2210202030 UTC, 2210211445 UTC UNTIL 2210212130 UTC, 2210221445 UTC UNTIL 2210222130 UTC, AND 2210231445 UTC UNTIL 2210232130 UTC. DUE TO NAS JACKSONVILLE AIRSHOW AERIAL DEMONSTRATIONS. WAYNE BOGGS, TEL 904-542-2546, IS THE POINT OF CTC. NAVY JACKSONVILLE /NIP/ ATCT, TEL 904-542-2511, IS THE CDN FAC. 202210201600-202210232130
 
You said it yourself. Based off of CRG. Only so much precision. And why worry about such a small offset?
 
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Maybe the airshow TFR is centered over the aerobatics box and the box is slightly offset from the center of the airport?

Or it’s a rounding error?
 
Not a plotting issue, just slightly different centerpoints and radii.

The Class D is 5.3 nm radius centered on 30-14-01N/81-40-34W
The TFR is 5 nm radius centered on 30-14-02N/81-40-22W
 
A while ago I saw a NOTAM for a TFR that was centered on the Route 28 / Sterling Blvd intersection just NE of IAD. In actuality, W was visiting a building immediately next to mine about three blocks from where the TFR center was plotted. We had to move all our cars out of of one side of our building per Secret Service request. We did get to watch the president get out of his car from one of our office windows.
 
kkoran said:
Not a plotting issue, just slightly different centerpoints and radii.

The Class D is 5.3 nm radius centered on 30-14-01N/81-40-34W
The TFR is 5 nm radius centered on 30-14-02N/81-40-22W
Click to expand...


The real question, though, is how was the center for the TFR determined, and why?
 
Half Fast said:
The real question, though, is how was the center for the TFR determined, and why?
Click to expand...

Rounding.

Based off the CRG VOR, and you gotta pick a 0.tenth distance to base it off of.
 
Lindberg said:
Where at the airport?
Click to expand...


FAA INFORMATION EFFECTIVE 06 OCTOBER 2022
Location
FAA Identifier: CRG
Lat/Long: 30-20-10.8000N 081-30-52.0000W
30-20.180000N 081-30.866667W
30.3363333,-81.5144444
(estimated)​

Or the ladies' restroom in the tower, which is probably the same spot.
 
Half Fast said:
FAA INFORMATION EFFECTIVE 06 OCTOBER 2022
Location
FAA Identifier: CRG
Lat/Long: 30-20-10.8000N 081-30-52.0000W
30-20.180000N 081-30.866667W
30.3363333,-81.5144444
(estimated)​

Or the ladies' restroom in the tower, which is probably the same spot.
Click to expand...
Great. Now what airborne equipment is necessary to find a point that's x miles at a yyy degree bearing from that point? And how would you find that same point with precision on a sectional?
 
Lindberg said:
Great. Now what airborne equipment is necessary to find a point that's x miles at a yyy degree bearing from that point? And how would you find that same point with precision on a sectional?
Click to expand...

How is that different from finding the center point based on the VOR? Bear in mind that VOR nav receivers are not required equipment and many aircraft, including mine, don't have them.

Personally, I'd just draw the TFR concentric with the delta.
 
Half Fast said:
FAA INFORMATION EFFECTIVE 06 OCTOBER 2022
Location
FAA Identifier: CRG
Lat/Long: 30-20-10.8000N 081-30-52.0000W
30-20.180000N 081-30.866667W
30.3363333,-81.5144444
(estimated)​

Or the ladies' restroom in the tower, which is probably the same spot.
Click to expand...

That would really offset the TFR considering it was "centered" over NIP. :D
 
EdFred said:
That would really offset the TFR considering it was "centered" over NIP. :D
Click to expand...


LOL! Yep. Oops!

I used to live just to the west of that airfield, too. Then after I moved from home my folks moved to a place near Doctor’s Lake. You’d think I should know that area better.... :)
 
Half Fast said:
How is that different from finding the center point based on the VOR? Bear in mind that VOR nav receivers are not required equipment and many aircraft, including mine, don't have them.

Personally, I'd just draw the TFR concentric with the delta.
Click to expand...
The center of a VOR is a dot on the sectional. Most airport symbols are 2 miles wide. And you don't need a VOR receiver to find a VOR, do you? Also, making the TFR coextensive with the D only works if the TFR is centered on an airport; most aren't. So you'd have one system for marking the location of some TFRs and a different system for the rest.
 
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kkoran said:
Not a plotting issue, just slightly different centerpoints and radii.

The Class D is 5.3 nm radius centered on 30-14-01N/81-40-34W
The TFR is 5 nm radius centered on 30-14-02N/81-40-22W
Click to expand...

Half Fast said:
Sure, but why base it off the VOR in the first place, rather than the airport?
Click to expand...

exactly my thoughts

and yeah I get the the VOR and radial is a point on the chart and in the databases but so is the class D...
just have the notam say something like like overlying the boundaries of the KNIP class D, surface to FL9999 or whatever.... then everyone knows to basically stay out of the class D and don't fly over it either..... which is I'll bet how pretty much everyone considers it now anyway... I doubt any pilots are plotting that random point and radius.

What am I missing in that? How would that be worse?
 
Read the NOTAM order 7930.2S for how all NOTAMs are to be formatted! The reason is to locate the NOTAM applicable area in reference to the nearest VOR.
 
John Collins said:
Read the NOTAM order 7930.2S for how all NOTAMs are to be formatted! The reason is to locate the NOTAM applicable area in reference to the nearest VOR.
Click to expand...


Of course, but why must it be that way? That order can be changed. I think it comes down to “because that’s the way we done it for half a century, and get off my lawn!”
 
Half Fast said:
Of course, but why must it be that way? That order can be changed. I think it comes down to “because that’s the way we done it for half a century, and get off my lawn!”
Click to expand...
Because VORs are things you used to find your position in space and define other points in space. Airports are things you navigate to.
 
Half Fast said:
Nor does everyone have a VOR receiver. Some have no electrical system at all.
Click to expand...
Covered. VORs work if you have a VOR receiver or GPS. Airports work only if you have GPS. If you have neither, neither works. But you can find distance and radial from a VOR on a sectional, but not distance and radial from an airport (at least not as easily).
 
Lindberg said:
Covered. VORs work if you have a VOR receiver or GPS. Airports work only if you have GPS. If you have neither, neither works. But you can find distance and radial from a VOR on a sectional, but not distance and radial from an airport (at least not as easily).
Click to expand...


But when we’re placing the TFR over an airport, as in this example, referencing the airport makes the whole thing trivial. We don’t have to go find distance and radial from anything. All we need is something along the lines of “...concentric with the KXXX class D and exceeding its boundary by 0.5nm...” When we’re creating a TFR for an airshow over an airport, that would be simpler and clearer than referencing some VOR twenty miles away.

Referring to a VOR is not the only way to define airspace. Look at some of the odd-shaped MOAs, for example.
 
Half Fast said:
But when we’re placing the TFR over an airport, as in this example, referencing the airport makes the whole thing trivial. We don’t have to go find distance and radial from anything. All we need is something along the lines of “...concentric with the KXXX class D and exceeding its boundary by 0.5nm...” When we’re creating a TFR for an airshow over an airport, that would be simpler and clearer than referencing some VOR twenty miles away.
Click to expand...

Lindberg said:
Also, making the TFR coextensive with the D only works if the TFR is centered on an airport; most aren't. So you'd have one system for marking the location of some TFRs and a different system for the rest.
Click to expand...
 
Brad W said:
But why not just define the TFR based on the Class D...or at least the class D's center point?
Click to expand...

I really don't know for sure, but one thought that occurs to me is that older (non-gps) based RNAV systems don't use Airport Waypoints but instead use VOR/DME or VOR/VOR located points.
Interestingly I recently learned you can create waypoints in the Garmin 430 this way also, just never had any reason to try before.

Brian
 
Half Fast said:
Nor does everyone have a VOR receiver. Some have no electrical system at all.
Click to expand...
and even those folks....with an old time paper sectional can find that airport and class D airspace no sweat..... but finding some point based on the radial... yeah maybe with a plotter and pencil....but with with a much higher chance for error
 
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