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.

"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

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

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?

"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

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
...

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 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

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.