Can GPS be *too* accurate? Do I need some XTE??

My mistake...I misread this. Sorry!




"Dan Girellini" wrote in message
...
== Bill Denton writes:

"Dan Girellini" wrote in message

I thought Class C services included IFR/VFR separation. Is that
old/wrong
information?

No, separation is not provided by ATC.

Can you explain how I'm misinterpreting this from the AIM?

[3-2-4] Class C Airspace
...
e. Aircraft Separation. Separation is provided within the Class C
airspace
and the outer area after two-way radio communications and radar
contact
are established. VFR aircraft are separated from IFR aircraft
within the
Class C airspace by any of the following:

1. Visual separation.

2. 500 feet vertical; except when operating beneath a heavy jet.

3. Target resolution.

--
PGP key at http://www.longhands.org/drg-pgp.txt Key Id:0x507D93DF

"Bill Denton" wrote in message
...
I noticed the later posts referenced a set of "rules" for setting up the
"error", but absent those, you are back to the same old game of chance.
What's to prevent another pilot from picking a corresponding "error" that
would still maintain the head-on courses?


Well, if *I* were choosing a *parallel offset*, it would always be to the
*right* of direct-track. Maybe the guy on the reciprocal track would think
to do the same.


And I don't know if this is a trick question, but if you are at 6000 (no
+500) wouldn't you be on an IFR flight plan, talking to ATC, and receiving
traffic advisories?

Well, I don't do IFR, but if you wish, change the scenario to my westbound
Cessna at 6500. And we are all "looking out", but just at the time we
appear as dots in each others windshield, my wife drops a water bottle that
rolls under my feet, so I bend down to get it, and she watches me. He's
been in the cockpit for 3 hours, in cruise descent, and his kid in the back
seat is a little antsy, and he's just realized he needs to look up a
frequency in the Airports and Frequency guide, because its kind of smudged
on his chart; he didn't think he'd need it, but what the hell.

The question was not meant to be tricky, nor to suggest that I am going to
throw my A/P onto the GPS and read the newspaper, instead of looking out the
window. I am just wondering out loud if super-accurate GPS nav creates a
"reduced chance" of horizontal clearance, over previous nav methods, given
the usual weaknesses and foibles of human pilots.






"Icebound" wrote in message
...
In the "good old" VOR days, it must have been pretty difficult to fly
down
the centerline of an airway (or of any direct track).

So an eastbound VFR/IFR aircraft descending from 7500/7000 to his
destination, was more than likely to avoid traffic... on the reciprocal
track passing him by at 6500 or 6000... by some significant horizontal
error-distance, even if they didn't see each other (big sky theory :-) ).

GPS horizontal accuracy with WAAS is already in the order of magnitude of
a
Cessna's wingspan, and some are talking about getting it down to mere
inches.

So the question is: If my Westbound Cessna at 6000 feet (with the
autopilot
keeping it happily on the GPS-track centerline) meets the descending
Bonanza
on the reciprocal track between the same two airports (using a similar
GPS/a-p combo), there is a distinct possibility that the horizontal
clearance may be zero...

...so is there anything in the current crop of GPS and/or Autopilot
systems
that allow me to maintain a small cross-track error of my choosing,
without
actually entering off-navaid-off-airport waypoints? ...or do we care; am
I
overly concerned???

"SelwayKid" wrote in message
om...
"Icebound" wrote in message
...

In the "good old" VOR days, it must have been pretty difficult to fly
down
the centerline of an airway (or of any direct track).

....snip...

As for being difficult to fly the VOR, it was/is no more difficult
than flying a compass heading and holding it.....which many pilots
seem unable to do anymore. They would prefer that electronic gadgets
do their flying for them and no thoughts as to what happens when the
electrodes take a vacation.


Never having flown a VOR course myself... I still doubt very much that any
two pilots (OR auto-pilots), flying reciprocal headings between two VORs,
would both be able to *simultaneously* hold a course to within 10 feet of
the centre-line for the whole course, considering the receiver errors and
that the VOR radial-signal *itself* probably varies more than that.

I could be wrong.

"Cloud clearance" was what I was referring to; sorry for my lack of
clarity...




"Newps" wrote in message
...


Bill Denton wrote:

I am not sure what your point about VFR-on-top is, but as a reminder to
you, in the US VFR-on-TOP is a specific IFR clearance that must be
requested.


And if you are granted that clearance, you will be flying under what are
essentially Visual Flight Rules, you will be allowed to deviate from
your
as-filed flight plan,

No. You must follow the flight plan just as if you were regular IFR.
Slight deviations for cloud clearance are OK. If you want a different
route then you must ask for and receive a new clearance.

"Newps" wrote in message
...

No. You must follow the flight plan just as if you were regular IFR.
Slight deviations for cloud clearance are OK. If you want a different
route then you must ask for and receive a new clearance.


IFR "VFR on top" routing remains the same but you fly at VFR altitudes
(cardinal altitude plus 500) of your choice while remaining in VMC.

Allen

The only time this would really be an issue would be if the other aircraft
were on an exact reciprocal course. And even if he used a corresponding
offset, he would still be 1,000 feet above or below you...



"Icebound" wrote in message
...

"Bill Denton" wrote in message
...
I noticed the later posts referenced a set of "rules" for setting up the
"error", but absent those, you are back to the same old game of chance.
What's to prevent another pilot from picking a corresponding "error"
that
would still maintain the head-on courses?


Well, if *I* were choosing a *parallel offset*, it would always be to the
*right* of direct-track. Maybe the guy on the reciprocal track would
think
to do the same.


And I don't know if this is a trick question, but if you are at 6000 (no
+500) wouldn't you be on an IFR flight plan, talking to ATC, and
receiving
traffic advisories?

Well, I don't do IFR, but if you wish, change the scenario to my westbound
Cessna at 6500. And we are all "looking out", but just at the time we
appear as dots in each others windshield, my wife drops a water bottle
that
rolls under my feet, so I bend down to get it, and she watches me. He's
been in the cockpit for 3 hours, in cruise descent, and his kid in the
back
seat is a little antsy, and he's just realized he needs to look up a
frequency in the Airports and Frequency guide, because its kind of smudged
on his chart; he didn't think he'd need it, but what the hell.

The question was not meant to be tricky, nor to suggest that I am going to
throw my A/P onto the GPS and read the newspaper, instead of looking out
the
window. I am just wondering out loud if super-accurate GPS nav creates a
"reduced chance" of horizontal clearance, over previous nav methods, given
the usual weaknesses and foibles of human pilots.






"Icebound" wrote in message
...
In the "good old" VOR days, it must have been pretty difficult to fly
down
the centerline of an airway (or of any direct track).

So an eastbound VFR/IFR aircraft descending from 7500/7000 to his
destination, was more than likely to avoid traffic... on the reciprocal
track passing him by at 6500 or 6000... by some significant horizontal
error-distance, even if they didn't see each other (big sky theory
:-) ).

GPS horizontal accuracy with WAAS is already in the order of magnitude
of
a
Cessna's wingspan, and some are talking about getting it down to mere
inches.

So the question is: If my Westbound Cessna at 6000 feet (with the
autopilot
keeping it happily on the GPS-track centerline) meets the descending
Bonanza
on the reciprocal track between the same two airports (using a similar
GPS/a-p combo), there is a distinct possibility that the horizontal
clearance may be zero...

...so is there anything in the current crop of GPS and/or Autopilot
systems
that allow me to maintain a small cross-track error of my choosing,
without
actually entering off-navaid-off-airport waypoints? ...or do we care;
am
I
overly concerned???

Allen wrote:

"Newps" wrote in message
...

No. You must follow the flight plan just as if you were regular IFR.
Slight deviations for cloud clearance are OK. If you want a different
route then you must ask for and receive a new clearance.



IFR "VFR on top" routing remains the same but you fly at VFR altitudes
(cardinal altitude plus 500) of your choice while remaining in VMC.

Like I said.

Allen wrote:


IFR "VFR on top" routing remains the same but you fly at VFR altitudes
(cardinal altitude plus 500) of your choice while remaining in VMC.


"Newps" wrote in message
...
Like I said.


Yes, sorry, I was just trying to clarify that although it is an IFR
clearance you are flying at VFR altitudes.

Allen

wrote in message ...


Blueskies wrote:



At midcourse, add a waypoint offset to one side or the other by a couple of miles. The enroute time would be changed
minimally...

But, that wouldn't be a parallel offset and would result in crossing the two end points precisely on course.

Also, the offset should be much smaller than 2 miles for domestic airspace operations.



But the end points are where you want to be - one is where you started and one is where you are going. If you have a
system that does not have the parallel course function, then this would be a simple solution. If you want perfect, then
plot a course using multiple waypoints...PIC chooses....

"Bill Denton" wrote in message
...
An even number of hundreds of feet is reserved for IFR flights (5,000 or
6,000). VFR flights must be +500 (5,500 or 6,000). If you see someone
breaking the rules by flying VFR at 6,000 feet you should report them;
it's
your safety that's at stake.

Cruising altitudes need only be observed when above 3000' AGL. There are
plenty of places in the US where 6000' is NOT 3000' AGL, including Denver
(which Peter specifically mentioned).

Feel free to report a VFR pilot flying near Denver at 6000' for violating
the cruising altitude rules, but I doubt you'll find anyone to take you
seriously.

This is not a matter of winning an losing, it's a matter of learning the
rules and assuring everyone's safety.

It sure seems like it's a matter of "winning an [sic] losing" to you. Your
original reply to the original poster made implication that, since the
aircraft at 6000' must be IFR (not even necessarily true, but for the sake
of argument let's grant that), the pilot would be receiving traffic
advisories and so didn't need to worry about aircraft climing through his
cruise altitude of 6000'.

Your implication was patently false, and your continued insistence on trying
to introduce new, unrelated topics to the discussion sure make it seem like
you've dug your heels in and are willing to do pretty much whatever it takes
to avoid admitting that you made a mistake in your original reply.

If it's not a matter of "winning an [sic] losing" to you, why so resistant
to admitting your mistake?

Pete