Violating Airspace with GPS

It appears that a lot of pilots are violating airspace even with GPS on
board.

I would like to hear some feedback as to how pilots are violating airspace
with GPS. I address this in my online book, www.cockpitgps.com. I have my
hypothesis, but I would like to hear your experience or scenarios that you
have heard involving this issue.

Also of interest is how you might be using GPS to successfully avoid
airspace violations.

Other hypothesis are also welcome.

Thanks,

John Bell
www.cockpitgps.com

Here is my hypothesis:

I have already mentioned in my discussion of database currency that you
should set up a routing around any airspace and check it with a current
chart before flight. Even with a current database, it is possible for the
GPS to get you into trouble with airspaces.
Aviation receivers can be setup to display airspace boundaries and to give
warnings before entering certain airspace classifications such as category B
airspace. These warnings can be a great benefit or a nuisance depending on
the type of flying that you are doing. Thus, most receivers allow you to
turn them on or off. Additionally, which boundaries will display and at what
point of zooming out they will disappear can be set. The ability to make
these settings is a good feature and I would not want to see this changed.
However, it is possible to have the GPS not display or not warn of an
impending airspace violation if you have the GPS set up incorrectly for the
mission.
Even if the airspace boundary is displayed, it is often difficult to decide
what boundary a given line applies to. On the Garmin aviation receivers it
is possible to cursor over the point to get a description. On a handheld GPS
just press the rocker pad up, down, left, or right to start moving the
cursor. On the GPS 400 and 500 series, press in on the knob and then start
moving the cursor. Move the cursor to highlight the line and press the ENTER
button to get information on the airspace. This is a great feature at the
planning stage and is occasionally useful in flight. When you have
preplanned the route and have a route line, the context of the border is
obvious. However, I think that it is possible to confuse borders and violate
airspace without first creating a route using a chart before flight.

"John Bell" wrote in message om...

Other hypothesis are also welcome.

Class B airspace, not category B.

Your simplified definition of GPS, while one of the common ones often espoused
has no basis in reality. This is not how GPS works.

Your information on RAIM is wrong. What is unique about the RAIM used in IFR
approved GPS's is not that it determines when the satellite geometry is giving you
an error NOW, but computes if it will fail while during the expected duration of flying
an instrument approach.

In article ,
John Bell wrote:

I would like to hear some feedback as to how pilots are violating airspace
with GPS.

Someone here just posted about busting SEA's class B (partly) due to
being zoomed in too far to get the big picture.

I flew straight into a class D instead of skirting it because I hadn't
been using the GPS map for anything up to that point and someone else
had switched it (rental plane) from track-up to north-up. I would have
missed it (my pilotage was fine) but the map put it just north of me
which I read as 'right in front of me' so I turned while I tried to
figure out how I could possibly be where it said I was...

--
Ben Jackson

http://www.ben.com/

I will see where I wrote category B instead of class B. It is simply a
typo. Thanks for catching that.

I am certainly up for a better explanation of how GPS works. Indeed my
information comes from the common espousals.

I understand the concept of RAIM prediction, that the GPS can predict the
unavailability of RAIM. However, I was not aware that RAIM had the ability
to predict as oppose to detect positioning errors.

I would appreciate further information on either basic GPS or RAIM.

John Bell


"Ron Natalie" wrote in message
m...

"John Bell" wrote in message
om...

Other hypothesis are also welcome.

Class B airspace, not category B.

Your simplified definition of GPS, while one of the common ones often
espoused
has no basis in reality. This is not how GPS works.

Your information on RAIM is wrong. What is unique about the RAIM used in
IFR
approved GPS's is not that it determines when the satellite geometry is
giving you
an error NOW, but computes if it will fail while during the expected
duration of flying
an instrument approach.

I use a Garmin 300 IFR GPS .. and a Garmin 196 handheld. I keep the IFR
database
current and update the handheld about once a year. I've had no trouble
working
around and under the Class B shelves using them. When compared to prominent
landmarks (roads, etc) that help identify the boundaries, they seem to be
highly
accurate. Some Class B's have VFR waypoints shown on the TAC and those
help. An important thing is to keep the zoom set correctly so you can
identify
just where you're at in relation to the different B floors. If you're zoomed
in
too close .. you may think you're under the wrong one. I like to zoom so I
can
see the B space to it's outermost ring.


"John Bell" wrote in message
om...
It appears that a lot of pilots are violating airspace even with GPS on
board.

I would like to hear some feedback as to how pilots are violating airspace
with GPS. I address this in my online book, www.cockpitgps.com. I have
my
hypothesis, but I would like to hear your experience or scenarios that you
have heard involving this issue.

Also of interest is how you might be using GPS to successfully avoid
airspace violations.

Other hypothesis are also welcome.

Thanks,

John Bell
www.cockpitgps.com

Here is my hypothesis:

I have already mentioned in my discussion of database currency that you
should set up a routing around any airspace and check it with a current
chart before flight. Even with a current database, it is possible for the
GPS to get you into trouble with airspaces.
Aviation receivers can be setup to display airspace boundaries and to give
warnings before entering certain airspace classifications such as category
B
airspace. These warnings can be a great benefit or a nuisance depending on
the type of flying that you are doing. Thus, most receivers allow you to
turn them on or off. Additionally, which boundaries will display and at wh
at
point of zooming out they will disappear can be set. The ability to make
these settings is a good feature and I would not want to see this changed.
However, it is possible to have the GPS not display or not warn of an
impending airspace violation if you have the GPS set up incorrectly for
the
mission.
Even if the airspace boundary is displayed, it is often difficult to
decide
what boundary a given line applies to. On the Garmin aviation receivers it
is possible to cursor over the point to get a description. On a handheld
GPS
just press the rocker pad up, down, left, or right to start moving the
cursor. On the GPS 400 and 500 series, press in on the knob and then start
moving the cursor. Move the cursor to highlight the line and press the
ENTER
button to get information on the airspace. This is a great feature at the
planning stage and is occasionally useful in flight. When you have
preplanned the route and have a route line, the context of the border is
obvious. However, I think that it is possible to confuse borders and
violate
airspace without first creating a route using a chart before flight.

On Thu, 30 Oct 2003 19:08:37 GMT, "John Bell"
wrote in Message-Id:
:

Other hypothesis are also welcome.

It is imperative that a pilot maintain situational awareness at all
times. The responsibility is his alone. GPS is a valuable aid. The
pilot who relies upon GPS exclusively to provide situational awareness
soon learns that won't work; it only provides positional information
(and speed). Situational awareness encompasses a great deal more....

On Thu, 30 Oct 2003 20:38:40 GMT, "John Bell"
wrote in Message-Id:
:

I am certainly up for a better explanation of how GPS works.

Are you aware of this mailing list?

GPS for Aviation:

http://www.lsoft.com/scripts/wl.exe?...ISTSERV.UNB.CA

There are very knowledgable folks willing to answer all your questions
there.

Larry Dighera wrote

There are very knowledgable folks willing to answer all your
questions there.

:-) :-) Since John has written texts on GPS Navigation, I suspect
that he was pulling someone's leg.

http://www.smallboatgps.com/ http://www.cockpitgps.com/


Hi John, how's things going? Remember meeting at SnF?

Bob Moore

Many GPS and MFD displays are too crummy to be of any real use in avoiding
airspace. The Bendix-King displays are among the worst. Even the color MFD
display is only half VGA quality and uses magenta lines for everything from
depicting airspace to the flight planned route. It is very easy to mistake
an airspace line for something else with this unit. Also, most displays
cannot draw curved lines very well, so when you zoom into a lot of class B
you discover that instead of a circle it is a complex polygon.

I think the biggest troublemaker is the 'nearest' function on most GPS
units. The pilot punches in 'nearest' thinking that is the airport he wants
to go to when in fact the GPS selects some other waypoint. The pilot is busy
and does not do a good job of checking.

Another troublemaker is the flight plan route function. The pilot either
leaves out an intermediate waypoint or enters an incorrect one with the same
or a similar identifier, then follows the courseline right into airspace
where he does not belong. Another problem is not clearing out an old flight
plan before entering a new one. This is especially common on GPS units like
the King KLN 94. A pilot will select direct to an airport without clearing
the flight plan entered in a previous flight. When he wants to fly an
approach, he presses PROC, selects the approach, and appends it to the old
flight plan. Then he does not activate the approach and the next thing you
know he has wandered off 180 degrees from where he should be.

Getting confused on whether the CDI is displaying NAV or GPS information is
another source of trouble.

Pilots also blunder into airspace because they are fooling around with the
GPS instead of paying attention to what they are doing. They are
particularly likely to do this if the GPS goes off line for some reason. It
is an especially serious problem with handheld GPS.

Then there are outright database errors. Jeppesen mis-plotted some class B
airspace a few months ago and someone posted just recently that Jeppesen
missed that the Savannah VOR had been moved.

Of course, most airspace violations are of things like the Washington ADIZ
and TFRs, which are not in most GPS databases, depicted on any charts, or
otherwise easily accessible. In fact, even the FAA is unable to plot many of
these TFRs accurately. Many TFRs give as their center both a lat/long and a
radial/DME, which may be a mile or more apart -- this is a big deal when you
consider that a TFR may be only three miles in radius. Additionally, TFRs
may change size, shape and duration with little or no notice, long after the
pilot has taken off. The best navigation techniques in the world will not
help you with that.

The fundamental problem that I see the most is that pilots just get behind
the airplane. Instead of setting up the GPS in advance, they wait until the
last minute, attempting to do things like set up an approach as they enter
the final approach course. It gets pretty wild watching students do that.
Then they panic, wander off course, and get into airspace.

I do not claim to have made all these mistakes myself, of course.

"John Bell" wrote in message
om...
It appears that a lot of pilots are violating airspace even with GPS on
board.

I would like to hear some feedback as to how pilots are violating airspace
with GPS. I address this in my online book, www.cockpitgps.com. I have
my
hypothesis, but I would like to hear your experience or scenarios that you
have heard involving this issue.

Also of interest is how you might be using GPS to successfully avoid
airspace violations.

Other hypothesis are also welcome.

Thanks,

John Bell

I've had a couple of *near misses* with airspace. The first time, my GPS
database was outdated, and I realized fairly late that the paper map didn't
show the same thing the GPS map showed. The controlled airspace had
expanded from a 5(?) radius around Montgomery, Ala to 10 (?) miles, and my
GPS had the old data. I looked and looked at the map thinking "that's a
bigger circle than what shows on the magic box"... Then I put a scale on the
map and realized that my eyeball was correct. I was close enough that
evasive action was necessary.

Another time, I was climbing around a series of clouds in a scattered/broken
layer, reached "on-top" and realized that I was surprisingly near Atlanta's
Class "C". Again, I had to make a course correction to avoid the airspace.
Obviously, I focused too hard to pick the best route around the clouds, and
didn't focus enough on my actual position relative to the airspace...

KB