GPS -- Ending?
 

Having read the responses to and comments on my original post, I am
still left with a few questions:

If I am on the Bahama Bank or in the Bahamian Exumas or in Hawk Channel
off Key Largo or in a bay or "river" or "creek" off the Chesapeake Bay,
negotiating shoals on a cloudy and windy day and GPS goes out because
it was suddenly turned off, is that not an "end" for me?

Does anyone believe or expect GPS to be turned off only for a few
minutes or hours? I would expect weeks to months, or longer, of "ended"
signals.

And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."

wrote in message
ups.com...
having GPS suddenly go off? This may well be an "end."


Not the "end" if you maintain a proper watch and can still remember how to
navigate, using traditional methods we used before GPS.

I don't mean reverting to Celestial, just maintain your plot/log and use DR
until your obtain a position fix using other basic methods.

Of my 48 years of boating, only in the last 2 years have I had
GPS/Loran/digital charts. I will admit that I find GPS and digital charts
very accurate and convenient, to the extent that I frequently neglect to
maintain my plot. However, last summer I was reminded the hard way, when the
power failed to my nav station while I was negotiating (for the first time)
the tricky Hammersley Inlet (So. Puget Sound). With 6-8 knot current
running, there was little time to take bearings and plot position. In this
case, I relied on the "ole MK I Eyeball" and description provided in my
cruising guide (shoreline references, etc.).

IMHO, a brief loss (day/month or so) shouldn't be the ended of recreational
boating. Just an opportunity to employ the traditional methods we all should
be familiar with.

My opinion, FWIW.

Steve
s/v Good Intentions

Any book or reference on boating safety and navigation will tell the prudent
mariner to NEVER depend on only one source of information for navigation....

I flew an airplane around Alaska in the 60's without a GPS or a VOR. We
used sectionals (which had large "uncharted areas) and pilotage (DR).
Sailed the windward, leeward, virgin islands and Bahamas in the 90's
without a GPS. Used charts, compass, knowledge of tides and currents,
coast pilot, dr and guide books. Never had a GPS until about three years
ago. Turning GPS off will not make all planes crash and ships run
aground. Learn how to navigate!.
krj

wrote:

Having read the responses to and comments on my original post, I am
still left with a few questions:

If I am on the Bahama Bank or in the Bahamian Exumas or in Hawk Channel
off Key Largo or in a bay or "river" or "creek" off the Chesapeake Bay,
negotiating shoals on a cloudy and windy day and GPS goes out because
it was suddenly turned off, is that not an "end" for me?

Does anyone believe or expect GPS to be turned off only for a few
minutes or hours? I would expect weeks to months, or longer, of "ended"
signals.

And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."

"Jeff Morris" wrote in message
...
wrote:
Having read the responses to and comments on my original post, I am
still left with a few questions:

If I am on the Bahama Bank or in the Bahamian Exumas or in Hawk Channel
off Key Largo or in a bay or "river" or "creek" off the Chesapeake Bay,
negotiating shoals on a cloudy and windy day and GPS goes out because
it was suddenly turned off, is that not an "end" for me?

Yes. I suggest you stay off the water. Those of us who know how to
navigate without GPS will thank you.

Does anyone believe or expect GPS to be turned off only for a few
minutes or hours? I would expect weeks to months, or longer, of "ended"
signals.

Actually, its most likely it will be degraded in some locality. It can be
made useless for terrorists by degrading the altitude component.


And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."

Commercial flights do not rely on GPS for approaches.

There are certain procedures available with GPS that are impractical (or
even undoable) for other navigation techniques. For instance I have made
dark and stormy approaches to a couple of harbors that I would not have done
without GPS and radar. These are comfortable with GPS with radar as a
backup and sometimes a calibrator. I would not attempt these by radar
alone.

Note that lights and other aids to navigation are being retired. In a few
years it will be impractical to sail a lot of places without GPS.

Aircraft use of GPS provides very quick problem detection. Implemented in
WAAS it provides an indication of non-proper operation in seconds.
Commercial airplanes certainly fly GPS approaches. I don't think there are
any precision approaches flown GPS yet...but non-precision approaches
certainly are. Eventually it is likely that the VOR/DME system and the ILS
will give way to GPS.

We are busily embedding GPS into the fabric of society. It is very
unlikely that the gov. will suspend the system at all...if they must it
will likely be for rather short periods of time.

Jim Donohue

On 20 Dec 2004 07:58:48 -0800, wrote:

Having read the responses to and comments on my original post, I am
still left with a few questions:

If I am on the Bahama Bank or in the Bahamian Exumas or in Hawk Channel
off Key Largo or in a bay or "river" or "creek" off the Chesapeake Bay,
negotiating shoals on a cloudy and windy day and GPS goes out because
it was suddenly turned off, is that not an "end" for me?


You reference to the Bahamas reminded me of a epsilon in the Sea of
Abaco in 1992. We were in our way back from a visit to Green Turtle
Cay. We were approaching the Whale Key Passage, about to go out into
the Atlantic and then back into the Abacos. Ahead of us were two
sailboats about to do the same. One had a stopped. The other radioed
him and asked if he was coming through. he responded that his GPS
had failed and he did not know where he was. All he had to do was
look around use his chart.


Does anyone believe or expect GPS to be turned off only for a few
minutes or hours? I would expect weeks to months, or longer, of "ended"
signals.

GPS will not be turned off world wide. It may be turned off in areas
of conflict. GMDSS is closely integrated with GPS. Turning off GPS
would endanger lives.


And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."

Commercial airline pilot rely on radio navigation beacons and flight
controllers to stay in their assigned air space. Instrument landings
also use radio beacons.

I would suggest that EVERYONE take a coastal navigation course. You
still have to understand tides and currents, chart symbols, compass
reading, plotting, the buoyage system, and position finding.

Jack

__________________________________________________
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
__________________________________________________

"Steven Shelikoff" wrote in message
...
On 20 Dec 2004 07:58:48 -0800, wrote:


It does get locally turned off once in a while for tests, military
exercises, etc. Usually they give plenty of warning. For instance,
here's an AP line about an outage back in June for the Carolinas to
Florida:
----------
Military testing system designed to jam GPS signals off coast

WILMINGTON, N.C. (AP) - Military officials are testing a system for
jamming signals from navigational satellites - an experiment that could
disable boaters' GPS devices and force them to rely on dead reckoning.
The test began Friday and will run through June 20, as part of a NATO
training exercise along the Atlantic Coast.

The Coast Guard said GPS signals will be unreliable or unavailable in
waters up to 60 miles off North Carolina and along the coast of northern
and central Florida. Officials said the testing may affect cell phones
as well as GPS navigation devices in boats, airplanes or cars.

Coast Guard stations are trying to get word out about the interference.

"What we kind of foresee happening is some confusion on the mariners'
end," said Petty Officer 1st Class David Christensen.
----------

And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."

No, that won't be the end either... unless the plane doesn't have a
pilot and it's being flown automatically, directed by GPS.

Steve

Actually Steve I think the military jammed the signal rather than turning it
off or degrading it. I also believe that there are antennas that would make
it difficult or impossible to jam a GPS particularly from a boat a few miles
away from the jamming site. I doubt the military will talk about it but
reasonably simple shielded antenna with deliberate limitation of the sky
viewed can probably provide pretty good reception even in the face of heavy
jamming.

On the other side jamming GPS in a relatively close in situation like a
harbor or a city is a piece of cake. I am sure the hacker community already
has a couple of desings on the internet.

None of this in any way applies that the gov can't easily screw around with
the signal to any desired extent. I would also point out it would be
relatively trivial for the gov to take out Russian or European sattellites
as well. Probably construable as an act of war but why else would the gov.
do it?
Jim Donohue

Jim Donohue wrote:
"Steven Shelikoff" wrote in message
...

On 20 Dec 2004 07:58:48 -0800, wrote:


It does get locally turned off once in a while for tests, military
exercises, etc. Usually they give plenty of warning. For instance,
here's an AP line about an outage back in June for the Carolinas to
Florida:
----------
Military testing system designed to jam GPS signals off coast

WILMINGTON, N.C. (AP) - Military officials are testing a system for
jamming signals from navigational satellites - an experiment that could
disable boaters' GPS devices and force them to rely on dead reckoning.
The test began Friday and will run through June 20, as part of a NATO
training exercise along the Atlantic Coast.

The Coast Guard said GPS signals will be unreliable or unavailable in
waters up to 60 miles off North Carolina and along the coast of northern
and central Florida. Officials said the testing may affect cell phones
as well as GPS navigation devices in boats, airplanes or cars.

Coast Guard stations are trying to get word out about the interference.

"What we kind of foresee happening is some confusion on the mariners'
end," said Petty Officer 1st Class David Christensen.
----------


And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."

No, that won't be the end either... unless the plane doesn't have a
pilot and it's being flown automatically, directed by GPS.

Steve


Actually Steve I think the military jammed the signal rather than turning it
off or degrading it. I also believe that there are antennas that would make

Right. That's what the article says, that the military was jamming GPS
signals from 60 miles off North Carolina and along the coast of northern
and central Florida. Of course, it doesn't really matter why it's
unusable ... whether it's jammed or turned off, it's still unusable.

it difficult or impossible to jam a GPS particularly from a boat a few miles
away from the jamming site. I doubt the military will talk about it but

If you increase "few" miles to a hundred miles or more, I'd agree. That
also depends on how they jam it. I.e., whether it's from the air or
ground. You can possibly get directional antennas and point the null in
the direction of the jammer. But that assumes there's only one and that
it's not somewhere above you. There's also ways of decreasing the
effectiveness of a jammer via signal processing. Of course, most
boaters don't go out equipped to handle possible jamming.

reasonably simple shielded antenna with deliberate limitation of the sky
viewed can probably provide pretty good reception even in the face of heavy
jamming.

It's got to be a little better than that. It has to have a pretty good
null specifically in the direct of the jammer. That's because GPS
signals are so weak (actually, they're below the level of background
noise and signal processing is needed to dig them out) that just about
any interference can cover them up.

On the other side jamming GPS in a relatively close in situation like a
harbor or a city is a piece of cake. I am sure the hacker community already
has a couple of desings on the internet.

You want a link? I've seen several make your own designs, complete with
schematics and parts lists with sources, design considerations, etc. To
take out GPS up to maybe 50 miles or more you only need about 4 watts
ERP, same as a CB walkie talkie. If you're equipped to handle the
jamming, you can overcome that and limit the range of the jammer to
maybe only a few miles. But again, most boaters aren't equipped to deal
with jamming and it would render the GPS of most boaters useless.

None of this in any way applies that the gov can't easily screw around with
the signal to any desired extent. I would also point out it would be
relatively trivial for the gov to take out Russian or European sattellites
as well. Probably construable as an act of war but why else would the gov.
do it?

It's just as trivial for another sophisticated government, one with
space capability, to take out our GPS satellites. Also probably an act
of war.

Steve

In a message dated 12/20/2004 1:43:11 PM Eastern Standard Time,
writes:
How many boats have you been on in the past five or so years that have
on their nav table: a divider, a chart ruler, or anything like these
simple and other nav instruments? I would guess you have found very
few, indeed if any.

Ahoy:

I have to admit that (1) my boat does have a nav table, dividers, and other
simple chart plotting tools, and that (2) I hardly ever use them.... I'm not
sure what other boater friends of mine have, but you've peaked my curiousity to
find out. Having said all this, I also agree that most of us do, in fact,
depend on the GPS alone more often than not. But if you are like me, I also
have something of an "eyeball DR" going on in my head almost all of the time.
This served me well once when I was navigating a course on the GPS to a distant
marker. At some point, the "eyeball DR" in my brain kicked in to say that what
I was seeing did not look right. I was way off course. It turned out that I
had transposed the waypoints for my destination when I loaded them into my
GPS....It was an interesting lesson that happily ended well

Good sailing to you.

w.

In article ,
Jeff Morris wrote:

Commercial flights do not rely on GPS for approaches.

Bzzzt, Wrong, Would you like to try for whats behind Door No. 1?

The FAA has certified CAT V GPS/ILS for about three years now.
It is a Aircraft Based System that only requires only a local
DGPS Beacon at the airport.


Me

In article ,
(Baybyter) wrote:

In a message dated 12/20/2004 1:43:11 PM Eastern Standard Time,
writes:
How many boats have you been on in the past five or so years that have
on their nav table: a divider, a chart ruler, or anything like these
simple and other nav instruments? I would guess you have found very
few, indeed if any.

Ahoy:

I have to admit that (1) my boat does have a nav table, dividers, and other
simple chart plotting tools, and that (2) I hardly ever use them.... I'm not
sure what other boater friends of mine have, but you've peaked my curiousity
to
find out. Having said all this, I also agree that most of us do, in fact,
depend on the GPS alone more often than not. But if you are like me, I also
have something of an "eyeball DR" going on in my head almost all of the time.
This served me well once when I was navigating a course on the GPS to a
distant
marker. At some point, the "eyeball DR" in my brain kicked in to say that
what
I was seeing did not look right. I was way off course. It turned out that I
had transposed the waypoints for my destination when I loaded them into my
GPS....It was an interesting lesson that happily ended well

Good sailing to you.

w.


Obviously, You have NEVER been on a Commercial Vessel bigger than 100
tonsGW. Every one I have been on has those, and a lot more. You
Weekend Masters ought to look at how the BIG BOYS navigate, and then
come back and tell us all what you found.......

Me

On 21 Dec 2004 15:15:35 GMT, (Baybyter) wrote:

In a message dated 12/20/2004 1:43:11 PM Eastern Standard Time,
writes:
How many boats have you been on in the past five or so years that have
on their nav table: a divider, a chart ruler, or anything like these
simple and other nav instruments? I would guess you have found very
few, indeed if any.

Ahoy:

I have to admit that (1) my boat does have a nav table, dividers, and other
simple chart plotting tools, and that (2) I hardly ever use them.... I'm not
sure what other boater friends of mine have, but you've peaked my curiousity to
find out. Having said all this, I also agree that most of us do, in fact,
depend on the GPS alone more often than not. But if you are like me, I also
have something of an "eyeball DR" going on in my head almost all of the time.
This served me well once when I was navigating a course on the GPS to a distant
marker. At some point, the "eyeball DR" in my brain kicked in to say that what
I was seeing did not look right. I was way off course. It turned out that I
had transposed the waypoints for my destination when I loaded them into my
GPS....It was an interesting lesson that happily ended well

I also have a nav table that can take a chart folded in half. When we
are offshore, as when crossing the Gulf of Maine, we plot the GPS
and/or Loran (not DR) position hourly.

Any anomalous behaviour will show up long before it matters under
those circumstances.

But, inshore near rocky coasts, like a lot of Maine, we plot danger
bearings whenever we are tacking to windward. It is a great
convenience to know the bearing angle you can safely reach on the next
headland, without having to see exactly where you are along the
course.

On smoother or sandier shores, with spaced-out contour lines, we can
tack by the depth sounder.

The common thread in all of these is awareness of surroundings, and
how they matter for pilotage.



Rodney Myrvaagnes J36 Gjo/a

The destruction of the World Trade Center was
a faith-based initiative. -- George Carlin

Me wrote:
In article ,
Jeff Morris wrote:


Commercial flights do not rely on GPS for approaches.


Bzzzt, Wrong, Would you like to try for whats behind Door No. 1?

The FAA has certified CAT V GPS/ILS for about three years now.
It is a Aircraft Based System that only requires only a local
DGPS Beacon at the airport.


Me
Are you sure of that? Are you really claiming that the thousands of
jets that are in the air now completely rely on GPS and would be unable
to land without it? Are you actually telling me that when I board a 757
to go to FL for Christmas the only nav system on board will be a GPS?

Baybyter wrote:
In a message dated 12/20/2004 1:43:11 PM Eastern Standard Time,
writes:
How many boats have you been on in the past five or so years that have
on their nav table: a divider, a chart ruler, or anything like these
simple and other nav instruments? I would guess you have found very
few, indeed if any.

Ahoy:

I have to admit that (1) my boat does have a nav table, dividers, and other
simple chart plotting tools, and that (2) I hardly ever use them.... I'm not
sure what other boater friends of mine have, but you've peaked my curiousity to
find out. Having said all this, I also agree that most of us do, in fact,
depend on the GPS alone more often than not. But if you are like me, I also
have something of an "eyeball DR" going on in my head almost all of the time.
This served me well once when I was navigating a course on the GPS to a distant
marker. At some point, the "eyeball DR" in my brain kicked in to say that what
I was seeing did not look right. I was way off course. It turned out that I
had transposed the waypoints for my destination when I loaded them into my
GPS....It was an interesting lesson that happily ended well

Good sailing to you.

w.

I'm not sure where anchorlt made the above comments - they don't show on
my servers or google. But ...

I'm a bit surprised at the comments - Certainly most of the long time
boaters I know have these tools and know how to use them. I'll admit
that most of them have given in to the temptation of relying on GPS, but
I'm sure all of them could cope with a sudden outage. For my own part,
I've lost GPS several times and found that I could revert to traditional
rather quickly if the need arises. As you say, a mental DR is always
maintained.

Although my boat is set up for computerized nav, I usually don't keep a
computer onboard. My GPS is 8 years old, and I haven't bothered getting
the charting chips for most areas I cruise to. Every year I do at least
one trip without GPS, just to stay in practice.

As for tools, I keep a set in a plastic box that comes on deck for
longer trips, or iffy weather. Although I don't often do running fixes
on deck, I usually do a few set and drift calculations a year. Frankly,
there's not much else to do when you're on a 4 hour watch; you might as
well practice navigation. (My wife, OTOH, saves a stack of magazines to
read while she's on watch, and thinks I'm just being geeky ...)

"Jeff Morris" wrote in message
...

Are you sure of that? Are you really claiming that the thousands of jets
that are in the air now completely rely on GPS and would be unable to land
without it? Are you actually telling me that when I board a 757 to go to
FL for Christmas the only nav system on board will be a GPS?

I am not sure what point you are making. There are airport approaches that
can only be executed by a GPS equipped airplane. So under at least some
weather conditions the only way to get into that airport is to fly a GPS
approach.

There are airplanes under the existing regulations that lack equipment that
used to be required for some instrument approaches.

All airplanes can of course resort to visual approaches. So when everything
breaks, you can run for a place where you can see. Note though that
occassionally there are no such places available.

I am not aware of any precision approach that has been approved for GPS.
Maybe Me knows something I don't. If so I would like to see a reference.

There appears no doubt in the direction of the FAA that the system will go
entirely GPS eventually...but that point is still many years in the future.
The present state is one of transition...changing from the procedures of
VOR/DME to those of GPS. So every year more and more of the procedures will
be GPS.


JIm Donohue

My point was simply that although the FAA has started approval GPS in
some situations, commercial flights, in particular large jets flying
into major cities, do not rely on GPS.

AnchorLt implied that anyone flying at the time of a GPS outage could be
in for "an ending." I think that commercial flights would be able to
cope since they do not rely exclusively on GPS. "me" rather rudely
pointed out the the FAA has begun approving GPS in some situations, some
I pointed out a few days ago, but missed the point the GPS is not the
sole means used by commercial aircraft.

I appreciate that there may be some situations GPS is the only way to
get into some airports, and that there may be not other backup. But
this scenario would apply to very few, if any commercial aircraft today.

Curiously, the scenario I remember given when SA was removed in 2000 was
that the 300 foot uncertainty in location meant that rescue vehicles
might go to the wrong side of a divided highway, causing perhaps fatal
delays. I wonder if the administration has some breakdown of the cost
in lives, accidents, and economic loss if GPS were shut down?


Jim Donohue wrote:
"Jeff Morris" wrote in message
...


Are you sure of that? Are you really claiming that the thousands of jets
that are in the air now completely rely on GPS and would be unable to land
without it? Are you actually telling me that when I board a 757 to go to
FL for Christmas the only nav system on board will be a GPS?


I am not sure what point you are making. There are airport approaches that
can only be executed by a GPS equipped airplane. So under at least some
weather conditions the only way to get into that airport is to fly a GPS
approach.

There are airplanes under the existing regulations that lack equipment that
used to be required for some instrument approaches.

All airplanes can of course resort to visual approaches. So when everything
breaks, you can run for a place where you can see. Note though that
occassionally there are no such places available.

I am not aware of any precision approach that has been approved for GPS.
Maybe Me knows something I don't. If so I would like to see a reference.

There appears no doubt in the direction of the FAA that the system will go
entirely GPS eventually...but that point is still many years in the future.
The present state is one of transition...changing from the procedures of
VOR/DME to those of GPS. So every year more and more of the procedures will
be GPS.


JIm Donohue

In article ,
Jeff Morris wrote:

Me wrote:
In article ,
Jeff Morris wrote:


Commercial flights do not rely on GPS for approaches.


Bzzzt, Wrong, Would you like to try for whats behind Door No. 1?

The FAA has certified CAT V GPS/ILS for about three years now.
It is a Aircraft Based System that only requires only a local
DGPS Beacon at the airport.


Me
Are you sure of that? Are you really claiming that the thousands of
jets that are in the air now completely rely on GPS and would be unable
to land without it? Are you actually telling me that when I board a 757
to go to FL for Christmas the only nav system on board will be a GPS?

Yes, I am sure of that, as I service the system on a bunch of 737-400's.
This is an option for all Boeing jets now. I am not saying that ALL
Jets have this system, I am saying that there is a CAT V GPS/ILS that
is FAA Certified and in use in the USA. Most of the commercial
carriers are using Inertial guidance systems, and the GPS/ILS is an
additional option for the Approch and Landing phase of flight, that
CAN either replace the old Microwave Ground Based System or be a
Redundent System to it. I also would say that 90% of the commercial
Air Fleet, has GPS inputs to the Navigation systems onboard.
Hell I saw a superb Glass Cockpit installed in a Cessna Archer,
that used GPS as a PRIMARY Navigation Instrument, with VOR as the
redundant backup. This was installed by an FAA Grant on an alaskan bush
plane. $50K of your tax dollars for each installation and there are a
buch of them in service now.


Me

In article G_4yd.8097$iD.5755@fed1read05,
"Jim Donohue" wrote:

"Jeff Morris" wrote in message
...

Are you sure of that? Are you really claiming that the thousands of jets
that are in the air now completely rely on GPS and would be unable to land
without it? Are you actually telling me that when I board a 757 to go to
FL for Christmas the only nav system on board will be a GPS?

I am not sure what point you are making. There are airport approaches that
can only be executed by a GPS equipped airplane. So under at least some
weather conditions the only way to get into that airport is to fly a GPS
approach.

There are airplanes under the existing regulations that lack equipment that
used to be required for some instrument approaches.

All airplanes can of course resort to visual approaches. So when everything
breaks, you can run for a place where you can see. Note though that
occassionally there are no such places available.

I am not aware of any precision approach that has been approved for GPS.
Maybe Me knows something I don't. If so I would like to see a reference.

There appears no doubt in the direction of the FAA that the system will go
entirely GPS eventually...but that point is still many years in the future.
The present state is one of transition...changing from the procedures of
VOR/DME to those of GPS. So every year more and more of the procedures will
be GPS.


JIm Donohue



Juneau, Alaska check it out....... the ILS Approch has a 45 degree
DogLeg 1000 feet before the end of the runway. Try that with the
old Ground based ILS system........


Me

Me wrote:
In article ,
Jeff Morris wrote:


Me wrote:

In article ,
Jeff Morris wrote:



Commercial flights do not rely on GPS for approaches.


Bzzzt, Wrong, Would you like to try for whats behind Door No. 1?

The FAA has certified CAT V GPS/ILS for about three years now.
It is a Aircraft Based System that only requires only a local
DGPS Beacon at the airport.


Me

Are you sure of that? Are you really claiming that the thousands of
jets that are in the air now completely rely on GPS and would be unable
to land without it? Are you actually telling me that when I board a 757
to go to FL for Christmas the only nav system on board will be a GPS?


Yes, I am sure of that, as I service the system on a bunch of 737-400's.
This is an option for all Boeing jets now. I am not saying that ALL
Jets have this system, I am saying that there is a CAT V GPS/ILS that
is FAA Certified and in use in the USA. Most of the commercial
carriers are using Inertial guidance systems, and the GPS/ILS is an
additional option for the Approch and Landing phase of flight, that
CAN either replace the old Microwave Ground Based System or be a
Redundent System to it. I also would say that 90% of the commercial
Air Fleet, has GPS inputs to the Navigation systems onboard.
Hell I saw a superb Glass Cockpit installed in a Cessna Archer,
that used GPS as a PRIMARY Navigation Instrument, with VOR as the
redundant backup. This was installed by an FAA Grant on an alaskan bush
plane. $50K of your tax dollars for each installation and there are a
buch of them in service now.


Me

Even so, this doesn't mean that commercial flights *rely* on GPS; it
only means that they *use* GPS. There's a big difference.

So what do you think would happen if the feds decided they had to shut
down the GPS system?

"Me" wrote in message
...
In article G_4yd.8097$iD.5755@fed1read05,
"Jim Donohue" wrote:

"Jeff Morris" wrote in message
...

Are you sure of that? Are you really claiming that the thousands of
jets
that are in the air now completely rely on GPS and would be unable to
land
without it? Are you actually telling me that when I board a 757 to go
to
FL for Christmas the only nav system on board will be a GPS?

I am not sure what point you are making. There are airport approaches
that
can only be executed by a GPS equipped airplane. So under at least some
weather conditions the only way to get into that airport is to fly a GPS
approach.

There are airplanes under the existing regulations that lack equipment
that
used to be required for some instrument approaches.

All airplanes can of course resort to visual approaches. So when
everything
breaks, you can run for a place where you can see. Note though that
occassionally there are no such places available.

I am not aware of any precision approach that has been approved for GPS.
Maybe Me knows something I don't. If so I would like to see a reference.

There appears no doubt in the direction of the FAA that the system will
go
entirely GPS eventually...but that point is still many years in the
future.
The present state is one of transition...changing from the procedures of
VOR/DME to those of GPS. So every year more and more of the procedures
will
be GPS.


JIm Donohue



Juneau, Alaska check it out....... the ILS Approch has a 45 degree
DogLeg 1000 feet before the end of the runway. Try that with the
old Ground based ILS system........


Me

Only published approach is RNAV non-precision approach. No dog leg close
in. There was a very sophisticated early experiment at Juneau that may have
been what your are referring to.

A quick check of the literature indicates there are no CAT I or better GPS
approaches. LAAS is supposed to enable this and there is talk that a
combination with Galileo will eventually enable precision approaches. I
believe at one point they were projecting CAT I with WAAS but decided
integrity is not high enough.

Jim

I think you will find many Airline fleets fully equipped with GPS today. It
appears that GPS is well on its way to become the standard primary
navigation system with VOR/DME as the secondary backup system.

For sophisticated operation it appears likely that GPS will be combined with
inertial.

The marine problem is in general much simpler. It is nice to be able to
stop or go real slow...a tactic not available in an airplane.

Jim

"Jeff Morris" wrote in message
...
My point was simply that although the FAA has started approval GPS in some
situations, commercial flights, in particular large jets flying into major
cities, do not rely on GPS.

AnchorLt implied that anyone flying at the time of a GPS outage could be
in for "an ending." I think that commercial flights would be able to cope
since they do not rely exclusively on GPS. "me" rather rudely pointed out
the the FAA has begun approving GPS in some situations, some I pointed out
a few days ago, but missed the point the GPS is not the sole means used by
commercial aircraft.

I appreciate that there may be some situations GPS is the only way to get
into some airports, and that there may be not other backup. But this
scenario would apply to very few, if any commercial aircraft today.

Curiously, the scenario I remember given when SA was removed in 2000 was
that the 300 foot uncertainty in location meant that rescue vehicles might
go to the wrong side of a divided highway, causing perhaps fatal delays.
I wonder if the administration has some breakdown of the cost in lives,
accidents, and economic loss if GPS were shut down?


Jim Donohue wrote:
"Jeff Morris" wrote in message
...

Jim Donohue wrote:
. . .
There appears no doubt in the direction of the FAA that the system
will go
entirely GPS eventually...but that point is still many years in the
future.
The present state is one of transition...changing from the procedures
of
VOR/DME to those of GPS. So every year more and more of the
procedures will
be GPS.

Agreed terminal approach GPS control is years down the road, but, isn't
the "free flight" initiative, which would allow airliners outside of
TRACON to route themselves, based on GPS transponders, pretty much
being fast tracked? Allegedly the system will gain significant
in-transit capacity so there's a big cost savings envisioned.

wrote in message
ups.com...

Jim Donohue wrote:
. . .
There appears no doubt in the direction of the FAA that the system
will go
entirely GPS eventually...but that point is still many years in the
future.
The present state is one of transition...changing from the procedures
of
VOR/DME to those of GPS. So every year more and more of the
procedures will
be GPS.

Agreed terminal approach GPS control is years down the road, but, isn't
the "free flight" initiative, which would allow airliners outside of
TRACON to route themselves, based on GPS transponders, pretty much
being fast tracked? Allegedly the system will gain significant
in-transit capacity so there's a big cost savings envisioned.


Free Flight - It is I think trapped in the bureaucracy. It is the
procedures and protocols that limit its application rather than technology.

V irtually any modern airliner, with or without GPS, knows where it is to
the nearest tenth of a mile or better. It is the development of a system
compatible with the existing air traffic control that is the killer. That
means small incremental improvements at best. Note that on time performance
continues to degrade even as they claim gains from implenting some of the
free flight tools.

One hopes...but they expect almost as many air traffic controllers in 10
years as now...does not give much reason form optimism.

Jim Donohue

Yep. Its ending and we're all going to be going back to using a
sextant and dead reckoning. I have to admit, I'd sure like to see
them turn off GPS. Maybe then there would be a few less people out
cruising around. GPS has made things much too easy therefore a lot
more people are out on the water. It's gotten so crowded over the
past couple years, cruising isn't much fun any more. Its gotten
pretty bad having to fight for a place to anchor - if allowed to
anchor at all - having to pay $120 a night for a place to tie up to a
dock. I vote turn it off for good.

On 20 Dec 2004 07:58:48 -0800, wrote:

Having read the responses to and comments on my original post, I am
still left with a few questions:

If I am on the Bahama Bank or in the Bahamian Exumas or in Hawk Channel
off Key Largo or in a bay or "river" or "creek" off the Chesapeake Bay,
negotiating shoals on a cloudy and windy day and GPS goes out because
it was suddenly turned off, is that not an "end" for me?

Does anyone believe or expect GPS to be turned off only for a few
minutes or hours? I would expect weeks to months, or longer, of "ended"
signals.

And mo Would anyone want to be in a commercial or private airplane
when making an initial approach in low ceiling weather to landing and
having GPS suddenly go off? This may well be an "end."