Questions on VFR sectionals and TACs

Mxsmanic,

It's just hard to figure out whether I'm inside or outside the
boundaries without a radius and center point.


You're going at this the wrong way. In flight, what you do is simply
look at the chart, find some ground features close to the border line
of the airspace, look out the window, find the same ground features -
and presto, you know where you are in relation to the airspace. For IFR
flight, airspace doesn't matter much, since the controller will do
everything necessary for you.

Also, many circular airspaces are centered around a VOR-DME, so there's
another help. Figuring the radius (which is normally standardized for
certain types of airspace) is pretty easy, since the scale of a
sectional is the same every time and you have a ruler.

The logic for class E lower limits is in IFR traffic being in it. Class
E means higher visibility requirements for VFR, so they can separate
themselves from IFR traffic. You may recall the thread in which we
tried VERY HARD to make you understand that concept. If you still
haven't grasped it, it's no surprise you don't understand the logic of
Class E lower limits. What comes round...

--
Thomas Borchert (EDDH)

Thomas Borchert writes:

You're going at this the wrong way. In flight, what you do is simply
look at the chart, find some ground features close to the border line
of the airspace, look out the window, find the same ground features -
and presto, you know where you are in relation to the airspace.

But that's just it: There are few ground features shown on the chart.
In some cases, a charted feature is near the border of the airspace,
but in many cases there is nothing along the border. Even with
landmarks, the best you can do is estimate.

I suppose one can argue that the differences among certain types of
airspace aren't that great, and a ballpark estimate will do. But if
they aren't that important, why bother to chart them?

It's all a strong argument for moving-map GPS systems, but one
shouldn't have to depend on those.

For IFR flight, airspace doesn't matter much, since the controller
will do everything necessary for you.

Yes, but this is a chart intended for VFR.

Also, many circular airspaces are centered around a VOR-DME, so there's
another help.

That does seem to be the case fairly often for Class B airspace, and
as long as it's a moderately regular layer cake, you can find out
where you are. I notice that some boundaries are clearly marked as
being on a particular radial or at a particular distance. Others are
marked as coincident with a feature such as a road, although how one
is supposed to recognize one road among others is not explained (in
the Phoenix TAC that I'm looking at, the entire area is crisscrossed
with a grid of streets; I'm not sure how I'd distinguish Camelback
Road from the other nearly identical streets to the north and south of
it.

Figuring the radius (which is normally standardized for
certain types of airspace) is pretty easy, since the scale of a
sectional is the same every time and you have a ruler.

If I can take my hands off the controls and turn to my chart to
measure it, that is.

The logic for class E lower limits is in IFR traffic being in it. Class
E means higher visibility requirements for VFR, so they can separate
themselves from IFR traffic.

I guess that makes sense--although it seems that essentially
everything is Class E, anyway. It sounds like this was not always so.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Mxsmanic,

But that's just it: There are few ground features shown on the chart.
In some cases, a charted feature is near the border of the airspace,
but in many cases there is nothing along the border. Even with
landmarks, the best you can do is estimate.


You know yourself how many times you've been told this here, but in a
real plane, this is a non-issue - as you would find out from one hour in
the air. Orientation by ground features is a very basic piloting skill
which is acquired during basic instruction. It works very well most of
the time for most pilots - and should you get lost, there are strategies
to find your position again. But, GPS moving maps have made it easier.
The consequence of using one is that you will pass a restricted airspace
much closer than you would using ground features because you will be
able to determine your location more precisely. If, OTOH, you're in
doubt, you'll just give the restricted airspace a wider berth.

--
Thomas Borchert (EDDH)

In article ,
Mxsmanic wrote:
Thomas Borchert writes:

Figuring the radius (which is normally standardized for
certain types of airspace) is pretty easy, since the scale of a
sectional is the same every time and you have a ruler.

If I can take my hands off the controls and turn to my chart to
measure it, that is.


Taking your hands off the controls is generally no big deal. Besides, if
you know you'll be flying near controlled airspace you take care of your
measuring and other planning before you get in the plane. Until you
fly a real plane you just can't appreciate how simple this is. Don't
make a mountain out of a mole hill.

--
Scott Post

Others are
marked as coincident with a feature such as a road, although how one
is supposed to recognize one road among others is not explained (in
the Phoenix TAC that I'm looking at, the entire area is crisscrossed
with a grid of streets; I'm not sure how I'd distinguish Camelback
Road from the other nearly identical streets to the north and south of
it.

Being a pilot in the Phoenix area I can at least help you out with that
one.
Camelback road can easily be identified by it's proximity to Camelback
mountain,
(from where it gets it's name) , and the mountain is easily identified
by it's shape
(take a wild guess as to what that is !). The other streets to the
north and south
are less easily identified, unless you are familiar with the area,
however they
can be identified by the locations of the high rise buildings. Most of
these are
clustered around central avenue, the uptown ones begin near Thomas,
the downtown
ones are noticeably seperated to the south. One comment I have to make
here is
it seems you ask these questions from a belief that pilots just take
off and go buzzing
around with no prior thought or preflight planning. I can assure you
that in the cases
of myself and the pilots I know, this is not the case. I am a
helicopter pilot so making
in flight measurements with a ruler/plotter is pretty much
impossible(rule of thumb works
for unexpected situations) but the point I am trying to make here is
that most pilots
don't just take off without already knowing where they are going and
how they are going to
get there. We can't plan for all the eventualities (oh look at that!
and a sightseeing detour
happens), but we must know where we are to know if said detour will be
feasible or not.
Most maps if you look closely enough will have a pretty clearly defined
vfr waypoint on them,
that you can use to identify your location on the map, (in Phoenix look
for the Beeline
Y or ASU or train tracks along Grand avenue or Boswell hospital on the
west side.


In short I guess what I'm trying to say is if you are unfamiliar with
an area, it simply
means that your preflight planning will, by necessity be more thorough.


Wayne
CPI-RTC

Others are
marked as coincident with a feature such as a road, although how one
is supposed to recognize one road among others is not explained (in
the Phoenix TAC that I'm looking at, the entire area is crisscrossed
with a grid of streets; I'm not sure how I'd distinguish Camelback
Road from the other nearly identical streets to the north and south of
it.

Being a pilot in the Phoenix area I can at least help you out with that
one.
Camelback road can easily be identified by it's proximity to Camelback
mountain,
(from where it gets it's name) , and the mountain is easily identified
by it's shape
(take a wild guess as to what that is !). The other streets to the
north and south
are less easily identified, unless you are familiar with the area,
however they
can be identified by the locations of the high rise buildings. Most of
these are
clustered around central avenue, the uptown ones begin near Thomas,
the downtown
ones are noticeably seperated to the south. One comment I have to make
here is
it seems you ask these questions from a belief that pilots just take
off and go buzzing
around with no prior thought or preflight planning. I can assure you
that in the cases
of myself and the pilots I know, this is not the case. I am a
helicopter pilot so making
in flight measurements with a ruler/plotter is pretty much
impossible(rule of thumb works
for unexpected situations) but the point I am trying to make here is
that most pilots
don't just take off without already knowing where they are going and
how they are going to
get there. We can't plan for all the eventualities (oh look at that!
and a sightseeing detour
happens), but we must know where we are to know if said detour will be
feasible or not.
Most maps if you look closely enough will have a pretty clearly defined
vfr waypoint on them,
that you can use to identify your location on the map, (in Phoenix look
for the Beeline
Y or ASU or train tracks along Grand avenue or Boswell hospital on the
west side.


In short I guess what I'm trying to say is if you are unfamiliar with
an area, it simply
means that your preflight planning will, by necessity be more thorough.


Wayne
CPI-RTC

In article ,
says...


OK. I confess that I don't see the logic behind so many changes in
Class E altitudes; some people at the FAA must have a lot of time on
their hands.



Most student pilots - those with a constructive attitude - try to learn
and understand before challenging and criticizing. There is certainly much
to criticize in the way aviation authorities do what they do, and there are
indeed a few things which simply appear to defy any rational approach to
comprehension. However, without having acquired even the most rudimentary
piloting skills or knowledge, one would be in a very poor position to
identify these issues, much less to make serious suggestions for
improvement.

Learning the nomenclature, color code and symbol legend of a VFR chart is
one of the most rudimentary piloting skills - whether you are flying a
sim or a training aircraft - if you haven't acquired this you are not
even ready to begin learning about flying. It's easy. An hour with any of
the excellent beginning aviation texts available and you will have most of
it. Another hour's review a week later and you'll only have to look at the
legend every once in a while to remember.

After this, anyone can have a question about class E surface areas, and
their relation to weather reporting, or those pesky "Presidential" areas
that show up on sectionals, but are never really explained - and people
here will galdly offer answers. But asking what a magenta circle is
indicates a real lack of interest in flying - this combined with
criticism for the way the FAA does things indicates a perverse attitude
toward flying.

GF

Dashed cyan is actually class E surface area.

Not cyan. Rather, class E is depicted by that horrible purply color the
FAA erroniously calls "magenta". What they print on the chart is not
magenta by any stretch of the imagination. Magenta is beautiful; you
can see magenta in the deluxe Crayola crayon box. The FAA color should
be called "FAA feh".

Cyan is more like a deep blue. Real cyan is also beautiful.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

Jose writes:

Not cyan. Rather, class E is depicted by that horrible purply color the
FAA erroniously calls "magenta". What they print on the chart is not
magenta by any stretch of the imagination. Magenta is beautiful; you
can see magenta in the deluxe Crayola crayon box. The FAA color should
be called "FAA feh".

Cyan is more like a deep blue. Real cyan is also beautiful.

Cyan is an equal blend of green and blue. It is used in process
printing as one of the four base colors. Magenta is another one of
those colors, and it is an equal blend of red and blue. The other two
colors are yellow and black. By blending these colors in various
proportions, you can produce virtually any color of the rainbow on
paper.

I'm not sure why the FAA chose these colors, but one possible reason
is that they blend easily when they overlay other colors, which
probably makes it easier to produce semitransparent borders with them.
You can get away with simply overprinting cyan and magenta halftones;
doing the same with primaries like red or blue (which are already
screened blends) might just get you a muddy black.

With modern electronic illustration and mapmaking this could probably
be changed, but it looks like aviation charts are still being drawn
and modified by hand--they lack the crisp look of something original
prepared on a computer. It must be hugely labor-intensive.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Mxsmanic wrote:
There are some mysteries that I've encountered while learning to read
VFR charts:

1. I see airports with dashed cyan circles around them that I presume
indicate Class D airspace (based on the chart legend). However, the
circles are not always the same size, and I don't see any indication
of their radii; how do I determine how far out the Class D circle
extends (short of measuring it by hand)? Also, is there a convention
for the center of the Class D circle (tower, or whatever?)? They
don't seem to be centered on anything easily identifiable.

The nominal diameter is 4.3 NM (5 SM). There
may be extensions either as class D or class E surface area that
accomodate the instrumetn approaches. They're centered on the
airport reference point.


2. The legend doesn't appear to explain lines that consist of a solid
cyan line with cyan dots inside. It seems to outline things like
wildlife refuges or parks and stuff like that. Is this just an extra
line style used for things that don't otherwise have line styles
assigned, or what? Are there any restrictions or other things to know
about spaces enclosed by these lines, or are they for information
only?


Symbols are explained more in the Aeronautical Chart User's Guide.
http://www.naco.faa.gov/index.asp?xm...ine/aero_guide

The blue line with the dots indicates a conservation area (wilelife
refuge, national park ,etc.).

Pilots are requested to stay 2000' above these (but it's not
mandatory).

3. I'm confused about Class E airspace. If I understand correctly,
the absence of any other indication on the chart means that Class E
starts at 1200' AGL, and extends to 18,000' MSL. If the shaded purple
border encloses an area, it's Class E starting at 700' AGL and still
extending to 18,000' MSL. If it's a shaded cyan border, it means ...
Class E starts at 1200' AGL and extends to 18,000' MSL?? (The chart
says "abuts Class G," but I'm not sure what they mean.)

Originally there was a lot less controlled airspace than there is
now. If you're out in parts of the country which is much more
desolate you'll fine the 1200' floors under airway, and the 700'
floors around airports that have instrument approaches that don't
have class E to the ground (transition areas). In most places
now, the 1200 stuff pretty much just overlaps everything and there
are magenta vignettes to take it down to 700'.

Originally, the magenta vignette was abutted with a blue vignette
showing the step up to 1200. Now they don't show the blue vignette
when it's bumping up against 700' or surface area boundaries, only
when it bumps up against uncontrolled airspace.



4. The cyan chain-link Class E border confuses me. Which side is
inside the Class E? The altitude is the floor of the Class E and it
still extends to 18,000' MSL, right? If there are different altitudes
on each side of the chain link, what does that mean, and where do I
look for the other border of the airspace? For example, just west of
Buckeye on the Phoenix sectional, there are chain links and stuff all
over the place, and I'm having trouble figuring out what the floors
are and where. Around Western Sky airport (W 113° 40' N 33° 46'
roughly), I see the shaded cyan border for Class E at 1200' AGL, but
in that area I see 7000 MSL, and a chain link on the right and bottom.
There are chain links next to airways, too. I don't know which
altitude applies where.

The zig/zag class E borders are used only in bizarre mountainous
area. The side with the text is the non-standard controlled
airspace floor.