Airspace & Charts Overview
Jeff Goin, February 2001, updated Aug 10, 2007.
Finding Legal Sites With
new areas by PPG is an experience in freedom seldom even imagined just a
few short years ago. As with most freedoms it carries some extra
responsibility…one of those is making sure you’re in allowable
Bible has a far more thorough and detailed treatment of the subject
but this should a provide a working knowledge of how to determine if the
air above is legal. Barring a knowledgeable local pilot, the best way to
learn the “where of legal air” is to purchase and become familiar with
the Aeronautical Sectional Chart for that area. Big cities have more
detailed versions covering just their vicinity called VFR Terminal Area
Charts…and they more detailed.
and Terminal Area charts are available from the local airports, the
and pilot shops such as Sporty's for
about $8 each. New, updated ones come out every 6 months and must be used
to avoid blundering into newly added restricted airspace (of which there
is much lately).
from charts are obviously NOT FOR NAVIGATION. They were out of date
when this was written, let alone when you're reading it.
other things, this short regulation says we must stay out of class A, B,
C, D and some E airspace, prohibited and restricted areas, and other
airspace as given by a notice to airman (NOTAM). There is also an
admonition on the charts to stay out of charted wildlife areas.
We can fly
in many of these airspace classes but must have prior permission by the
also visibility and cloud clearance requirements based on what kind of
airspace we operate in.
way to learn this information would be a session or two with a certified
FAA flight instructor. Next best would be some good videos such as
"The Complete Airspace Review" and "VFR Cross Country
Flying"...both from the well known producer of such flicks, King
They are about $30 each.
that for complete details, each chart has a legend on the back of the
folded cover that explains most of it’s contents. This article is
intended to help understand how it’s used in the context of our sport
without trying to dredge up every little nuance of VFR charts.
sectional chart is a great source of information, it is also the least
current. They are printed every six months and new airspace frequently
pops up or changes frequently. A necessary source of info for some of
these tips is the Flight Service Station (FSS).
times when prohibited airspace is created temporarily. That is when a
Notice to Airmen (NOTAM) is issued restricting overflight during the
affected time for listed locations and altitudes. In the current security
environment, adherence to these are critical.
information can be obtained by calling a Flight Service Station (FSS) at
1.800.wx-brief. Tell them you're an ultralight, where and when you want to
fly and they'll give you any pertinent info. A bonus of this call is that
you'll also be able to get weather around your area if desired (just ask
for an abbreviated briefing with local weather, forecast and NOTAMS).
example of when airspace will become off-limits by NOTAM is whenever the
president or other dignitary comes to town: they don’t want private
planes or ultralights (us) buzzing about for obvious reasons. They will
specify a bunch of areas and times that will cover the expected route,
including alternate routes they will travel. Nowadays these are taken
extremely seriously; blundering into one might be a one-time mistake.
time airspace is NOTAM’d off-limits is after a natural disaster. This is
an effort to keep the area clear for rescue or relief traffic. These cases
are usually going to be obvious because the disaster creating the airspace
will be all over the news.
boundaries will frequently be in the form of a radial and distance from a
VOR (see offset above).
example (reference the excerpt): a truck carrying propane explodes on the
highway southwest of Vero Beach. The highway is closed and a
rescue/firefighting operation gets underway. FAA managers, at the request
of local officials, will close the airspace over the area by issuing a
NOTAM - prohibiting overflight below 2000’ and within 2nm (nautical
miles) of an area defined by the 210° radial at 7nm. Flying there would
be particularly dangerous due to disaster related air traffic and would
guarantee yourself special attention: everybody in
officialdom knows you’re not supposed to be there.
if there has been such a disaster you’ll likely know about it and can
expect the area to be off limits. Since there’s likely to be cameras
rolling from the various news outlets it would be good to find out about
any possible restricted areas.
The ABC’s of
The most relevant piece of
knowledge regarding airspace is that almost anywhere you go, you're
probably launching in G airspace at the surface with E airspace overlying
it 700' (or 1200') overhead. Minimum for that airspace require remaining
clear of clouds and having at least a mile visibility. When you pop into E
airspace, airplanes are more likely to be found tere and you must maintain
at least 3 mile visibility and stay 500' below, 2000' to the side and
1000' above any cloud.
Class A airspace is above
18000’...no problem staying clear of that. Class B is where the big
airplanes land. There are only a handful of these around the country
surrounding the largest airports and generally we wouldn’t want to go
anywhere near them. Unfortunately they do usually block out otherwise
usable launches that are indeed far enough away, so we must go to the
The usual analogy of
the three dimensional chunk of air carved out by a “B” is the upside
down wedding cake (diagramed left). Near the airport it goes right down to
the surface, as you get further away from the primary airport the floor
goes above ground level, allowing us to fly in that area. That would be
flying beneath “B” airspace and is perfectly legal.
example, in the above depiction there is a ring with 80 over 40. That
means the B airspace goes from 4000' above sea level (ASL) to 8000' ASL.
So in the area of that ring you could fly up to 4000'. Keep in mind all
those little airplane guys know that and will frequently squeeze around
these rings just below those altitudes.
where it has 80 over SFC means from the surface up to 8000'. That is the
off-limits area for launching (or flying into at any altitude).
"B" areas don't have completely circular shapes, they follow
beaches, prominent roads, terrain and such so the pilots who are flying
visually can stay out of them. The Miami chart pictured is quite circular
with some of the inner sections following parts of the beach.
Class B Airspace and it's "upside down wedding cake" swath of
Class C and Terminal Radar
Class C is
designated just like class B but with a magenta line instead of blue. It
has altitudes depicted in the same way with a floor and ceiling and is
just as prohibited
airports, like the their larger "B" brethren have an approach
control facility associated with them.
airspace was designated into the alphabetic descriptions (for compliance
with world standards) there were distinct names for each type. One that
remains is the Terminal Radar Service Area (TRSA).
right is the Rockford, IL TRSA. There is not quite enough traffic to be a
class "C" and It is designated with a dark gray line. It is
permissible to fly in this airspace without talking to anyone although
there will be a control tower and class D airspace near the center (dashed
blue lines) which is prohibited (unless you have permission, of
primary purpose is to point out to airplane pilots that radar service is
available but participation is not mandatory.
If the lines are black like this than it's one of only a few TRSA's
(Terminal Radar Service Areas). If the lines are magenta than it's Class C
and if the lines are blue then it's Class B.
Tower Airports and Class D
with control towers are blue and those with no tower are magenta
(purple). Furthermore an airport with a control tower will generally have
a blue dashed line around it. That line designates “class D” airspace
which prohibits our operations (unless we talk to them).
class D airspace typically goes up 2500' above ground level (AGL) and the
above-sea-level (ASL) altitude is depicted in the box. The DPA airport
(left) shows 33 which is 3300' ASL. The airport elevation is 758.
When aviation charts use italics it usually is to indicate elevations
referencinv mean sea level (MSL and ASL are the same thing). This includes
airports, mountains and obstructions.
you could fly right above the DPA airport at 3400' ASL. While legal this
would be complete folly because airplanes will be taking off and landing
at the airport and many will be overflying for the same reason...they
don't have to talk to anyone. It is some very crowded airspace and they're
not looking for essentially stationary ppg's.
in the DPA example the 100/40 near the top of the picture. This airport
underlies Chicago's very busy O'Hare airport, the floor of who's B
airspace is at 4000'. So everyone not talking to either the DPA tower or
O'Hare approach is squeezing between 3300' and 4000' MSL.
there are a few control towered fields that do not have this "D"
airspace (no dashed line) and you can legally fly near these. It would
obviously be wise to check with the tower because they may have just
obtained the necessary traffic counts to receive their “D”
The DuPage airport (top left) has
Class D around it topping out at 3300' above sea level (ASL). Although
Kissimmee airport (bottom) has a control tower it does not have class D
airspace around it since there is no dashed line. You could legally fly
only a mile away from this airport although that should be done carefully
as it is obviously busy enough to have a tower. Also note this can change
at any time so consult the NOTAMs or, better yet, call the tower before
many flavors of airspace where the military stakes a claim. Most of it is
actually not forbidden zone but given the nature of their use it would
best be avoided. All military airspace is designated the same way with
rows of parallel lines in either blue or red (see MARIAN MOA below for an
also VR and IR's which are Visual Routes and Instrument
Routes. These thin gray lines are not restricted legally but be
aware they frequently fly very low and fast along them (up to 270
and Restricted areas generally are no-no’s. Flying in one of these while
it’s in use would be utter folly. But even these may allow
flight…they are in effect from different altitudes (sometimes only high
up) and different times or days. This information is usually located on
the chart. If planning on flying in one of these areas you must call the
Flight Service Station (FSS) at 800 WX-BRIEF to verify the times though.
The sectionals come out every 6 months and these times are updated every
56 days so the chart’s info could be old. Tell the FSS briefer you’re
an ultralight pilot and he will find out whether it’s “hot”. He has
a direct line usually to the controlling agency (usually the enroute
“center”) and will relay the information to you…and the call is
areas, Controlled Firing areas and MOA’s do not actually prohibit
flight…they are there as a warning that military operations will be
conducted and pilots should “look out”. Keep in mind some military
training involves low-altitude helicopter or jet training where they do
various “nap-of-the-earth” type work. That would put them smack in the
middle of our favorite altitudes.
the military pilots in these areas comply with FAA regs but these military
folks probably aren’t going to be looking for stray ppg’s!
not actually prohibited but the admonishment on the charts requests pilots
to remain at least 2000' AGL when overflying them. They are designated in
blue with a solid line that has dots running along just inside the
example to the left, the Verde River Bald Eagle Breeding Area roughly
follows a river. This area is about 2 miles wide. Note that it overlaps
another, rectangular shaped, wildlife area south of it (whose name is not
"PXR 025°". It is part of the PHX class B airspace depiction
and is the 25 degree radial from the PXR (Phoenix) VOR. It aids airplane
pilots who have the special VOR receiver equipment to identify the
outlines of the B airspace although most of this is now done with GPS.
Class E & G Airspace
all of our flying is going to be in this airspace. We can legally
take-off, fly around in, and land in both E & G airspace. The
difference between the two is only in the required cloud clearance and
visibility requirements. The vast majority of the United States is covered
by G (the least restrictive) and then E on top of that...meaning that our
freedom to fly is indeed bountiful. In those few areas, mostly out west,
where G airspace has not cap shown, the top is still 14,500 with E above
that. The practical difference is negligible because visibility and cloud
clearance requirements are the same.
areas of the country the G airspace goes from the surface up to 1200' AGL.
If there's a nearby airport that sometimes gets lowered to 700' AGL. Above
the G airspace is E which has more restrictive visibility requirements but
we can certainly fly in it.
airports where airplanes are likely to be letting down on an instrument
approach, the floor of E airspace lowers to 700 feet. That is depicted by
a shaded magenta outline. In the example around Pontiac airport it is a
circle but sometimes it has weird shapes with extensions that stick out.
example of Pontiac, the area within 5 miles of the airport up to 700' AGL
is class G airspace (requiring only a mile visibility). Above 700' is
class E airspace requiring 3 mile visibility. You could launch from the
airport with visibility as low as a mile but couldn't go over 700' unless
the visibility was at least 3 miles.
Class E Surface Area
Some airports are not
quite busy enough to have a control tower but are still busy. They may
have the Class E airspace lowered to the surface as depicted by dashed
magenta lines. The example at right, Truth or Consequences airport in New
Mexico shows a shaded magenta area around it, which lowers the E airspace
to 700' AGL then, inside that is a dashed magenta ring that lowers the
class E to the surface.
We are specifically
prohibited from flying here without permission.
Another example is where
a control tower airport has extensions around it where Class E is lowered to
the surface. Aurora, shown at right with the inset, is one example. The blue
area is the class D and the magenta area is class E to the surface. The
coloring was added only in the inset for clarity.
Permission comes from the
control tower where applicable, approach control if it's near a large
airport, or the Air Route Traffic Control Center which handles traffic
You can go
here to see about getting
permission to fly at these places.
most of the busy class B airspace areas there is a 30 mile ring that says
"Mode C". This has no bearing on our ability to fly inside that
The mode C
"veil" pertains to certified aircraft with an electrical system
and stipulates that they must have a transponder with altitude encoding.
That equipment transmits to the radar controllers their altitude along
with some other information. We, as ultralights, are exempt from this
requirement. Obviously we do have to stay out of the various layers of the
class B airspace.
I've found myself in a new area and one of the first tasks is to buy a
chart if I don't have one. Then by comparing what's on the chart with the
road map I can make sure I'm legal from an airspace perspective.
couple occasions the places where I really wanted to fly were in someone's
class D airspace. So far I have been able to secure permission by adhering
to agreed upon times, altitudes and routes.
this information will help in your own effort to beware of legal air.