OK, FAR Lawers we need your help!

Consider this:

Lateral error limits for an ILS approach are +/- 60 feet.
This is 0.01 degrees (1 degree=6000 feet, 0.1 degree=600 feet)
Granted, most of us only see +/- 15 feet with our GPS's, but WAAS/LAAS
are suppose to guarantee the tolerance.

john smith wrote:

Consider this:

Lateral error limits for an ILS approach are +/- 60 feet.
This is 0.01 degrees (1 degree=6000 feet, 0.1 degree=600 feet)
Granted, most of us only see +/- 15 feet with our GPS's, but WAAS/LAAS
are suppose to guarantee the tolerance.

Where did you come up with that?

wrote:

john smith wrote:


Consider this:

Lateral error limits for an ILS approach are +/- 60 feet.
This is 0.01 degrees (1 degree=6000 feet, 0.1 degree=600 feet)
Granted, most of us only see +/- 15 feet with our GPS's, but WAAS/LAAS
are suppose to guarantee the tolerance.


Where did you come up with that?

An FAA rep at a conference on LORAN approaches in 1985.

john smith wrote:

An FAA rep at a conference on LORAN approaches in 1985.

Well, he was full of it. Check the AIM for the LOC sensitivity and check
the TERPS chapter for ILS for the protected airspace.

wrote:
An FAA rep at a conference on LORAN approaches in 1985.

Well, he was full of it. Check the AIM for the LOC sensitivity and check
the TERPS chapter for ILS for the protected airspace.

Okay, I just took the dog for a walk and was pondering the subject.
To clarify...
An ILS is an "angled" approach, that is, each dot represents 2-degrees
of angle from the centerline. This is a converging cone.
A GPS approach (or LORAN) is a "parallel" approach. Each dot on the
display represents a line parallel to the centerline.
For example, a Garmin 430...
Outside 30 nm from the destination, the sensitivity is 5 nm per dot.
Inside 30 nm from the destination, the sensitivity changes to 1 nm per dot.
Two miles from the final approach fix in the approach mode, the
sensitivity changes to 0.3 nm per dot. This is 1800 feet, hence the
reason the approach is a non-precision approach. This is also the
minimum runway separation for parallel approachs on ILS's at many
airports. (I believe this has been increased to 2400 feet.) See the problem?
I probably should have said +/-60 feet for an ILS equivalent approach.
The discussion at that time was about how many decimal places a box need
to have and charts need to have printed.
I apologize for leaving out "details", you have to think about the
equipment and how it works.

What does this have to do with the discussion at hand?

Mike
MU-2

"john smith" wrote in message
...
wrote:
An FAA rep at a conference on LORAN approaches in 1985.

Well, he was full of it. Check the AIM for the LOC sensitivity and
check
the TERPS chapter for ILS for the protected airspace.

Okay, I just took the dog for a walk and was pondering the subject.
To clarify...
An ILS is an "angled" approach, that is, each dot represents 2-degrees
of angle from the centerline. This is a converging cone.
A GPS approach (or LORAN) is a "parallel" approach. Each dot on the
display represents a line parallel to the centerline.
For example, a Garmin 430...
Outside 30 nm from the destination, the sensitivity is 5 nm per dot.
Inside 30 nm from the destination, the sensitivity changes to 1 nm per
dot.
Two miles from the final approach fix in the approach mode, the
sensitivity changes to 0.3 nm per dot. This is 1800 feet, hence the
reason the approach is a non-precision approach. This is also the
minimum runway separation for parallel approachs on ILS's at many
airports. (I believe this has been increased to 2400 feet.) See the
problem?
I probably should have said +/-60 feet for an ILS equivalent approach.
The discussion at that time was about how many decimal places a box need
to have and charts need to have printed.
I apologize for leaving out "details", you have to think about the
equipment and how it works.

In article , john smith
wrote:

I probably should have said +/-60 feet for an ILS equivalent approach.

the +/-60 feet is approximately the tolerance for the ILS ground
system at the threshold. It would not include the tolerance for
the avionics nor the FTE.

--
Bob Noel
Seen on Kerry's campaign airplane: "the real deal"
oh yeah baby.

Mike Rapoport wrote:
What does this have to do with the discussion at hand?

It's just a twist it took based on a previous comment. :-)

Bob Noel wrote:
I probably should have said +/-60 feet for an ILS equivalent approach.

the +/-60 feet is approximately the tolerance for the ILS ground
system at the threshold. It would not include the tolerance for
the avionics nor the FTE.

What is FTE?
(The only other usage I have seen for that acronym is Full Time Employee.)

"john smith" wrote in message =
...
=20
=20
For example, a Garmin 430...
Outside 30 nm from the destination, the sensitivity is 5 nm per dot.
Inside 30 nm from the destination, the sensitivity changes to 1 nm per =
dot.
Two miles from the final approach fix in the approach mode, the=20
sensitivity changes to 0.3 nm per dot.=20


You must have confused full-scale sensitivity with "per dot" =
sensitivity.
Your numbers are wildly excessive, compared to my CNX80.
I could pull up the Garmin Simulator to check the 430, but so could you.
Let us know if the 430 really has that rotten sensitivity you mentioned.
---JRC---