"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."