Different WAAS altitude readings

Can't address your problem, but AIM 1-1-20(a)(8) tells us not to use GPS
altitudes. Doesn't say anything about WAAS...yet.

Bob Gardner

"Wyatt Emmerich" wrote in message
...
My Garmin 296 indicates 330 MSL at KHKS, which is correct. My Echo Flight
GPS indicates 140 MSL. Both are locked on to WAAS.

How can I have such a large discrepancy? Both units seem to be functioning
properly other than this.

Given this discrepancy, I understand why.

"Bob Gardner" wrote in message
...
Can't address your problem, but AIM 1-1-20(a)(8) tells us not to use GPS
altitudes. Doesn't say anything about WAAS...yet.

Bob Gardner

"Wyatt Emmerich" wrote in message
...
My Garmin 296 indicates 330 MSL at KHKS, which is correct. My Echo
Flight
GPS indicates 140 MSL. Both are locked on to WAAS.

How can I have such a large discrepancy? Both units seem to be
functioning
properly other than this.

"Bob Gardner" wrote in message
...
Can't address your problem, but AIM 1-1-20(a)(8) tells us not to use GPS
altitudes. Doesn't say anything about WAAS...yet.

1-1-20's title is "Wide Area Augmentation System (WAAS)." There is no
1-1-20(a)(8). 1-1-20(b) gives guidance and procedures for flying approaches
with vertical guidance from WAAS and says that some installations of WAAS
may be certified for precision approaches as having greater accuracy than
barometric altimeters.

I'm using the 2004 FAR-AIM as a convenience...guess I should have used my
Summit CD-ROM which is updated quarterly.

Bob

"C J Campbell" wrote in message
...

"Bob Gardner" wrote in message
...
Can't address your problem, but AIM 1-1-20(a)(8) tells us not to use GPS
altitudes. Doesn't say anything about WAAS...yet.

1-1-20's title is "Wide Area Augmentation System (WAAS)." There is no
1-1-20(a)(8). 1-1-20(b) gives guidance and procedures for flying
approaches
with vertical guidance from WAAS and says that some installations of WAAS
may be certified for precision approaches as having greater accuracy than
barometric altimeters.

I see that my reference should have been AIM 1-1-19(a)(8). Other than that,
the guidance remains the same.

I note the phrase "will be" sprinkled through the discussion of WAAS. Has
WAAS been approved for operational use? How many boxes have the
functionality described in 1-1-20?...I think the CX-80 does.

Bob Gardner

"C J Campbell" wrote in message
...

"Bob Gardner" wrote in message
...
Can't address your problem, but AIM 1-1-20(a)(8) tells us not to use GPS
altitudes. Doesn't say anything about WAAS...yet.

1-1-20's title is "Wide Area Augmentation System (WAAS)." There is no
1-1-20(a)(8). 1-1-20(b) gives guidance and procedures for flying
approaches
with vertical guidance from WAAS and says that some installations of WAAS
may be certified for precision approaches as having greater accuracy than
barometric altimeters.

Right now, the CNX-80 does not give vertical guidance, but that is
promised in software version 2.0, hopefully to be approved by Q3/2004.
That software v2.0 has been in flight test since Q4/2003.
I'm unaware of any box nearer than the CNX-80 to LPV capability.
---JRC---

"Bob Gardner" wrote in message =
...
I see that my reference should have been AIM 1-1-19(a)(8). Other than =
that,
the guidance remains the same.
=20
I note the phrase "will be" sprinkled through the discussion of WAAS. =
Has
WAAS been approved for operational use? How many boxes have the
functionality described in 1-1-20?...I think the CX-80 does.
=20
Bob Gardner
=20
"C J Campbell" wrote in =
message
...

"Bob Gardner" wrote in message
...
Can't address your problem, but AIM 1-1-20(a)(8) tells us not to =
use GPS
altitudes. Doesn't say anything about WAAS...yet.

1-1-20's title is "Wide Area Augmentation System (WAAS)." There is =
no
1-1-20(a)(8). 1-1-20(b) gives guidance and procedures for flying
approaches
with vertical guidance from WAAS and says that some installations of =
WAAS
may be certified for precision approaches as having greater accuracy =
than
barometric altimeters.

"John R. Copeland" wrote:

Right now, the CNX-80 does not give vertical guidance, but that is
promised in software version 2.0, hopefully to be approved by Q3/2004.
That software v2.0 has been in flight test since Q4/2003.
I'm unaware of any box nearer than the CNX-80 to LPV capability.
---JRC---

Most of the modern iron has Baro VNAV which, in addition to being authorized in the final approach
segment as primary vertical guidance where VNAV minimums are charted, is used extensively for
flying constant angle descents in the segments of an IAP prior to the Baro VNAV P-FAF. That's
different that LPV, which can only be used in the final approach segment where LPV minimums are
charted, and you have LPV approval.

If the CNX-80 will be able to do both Baro VNAV and LPV, that will be very advanced, indeed. Is
that the plan?

On Sun, 27 Jun 2004 04:21:24 -0700, wrote:

If the CNX-80 will be able to do both Baro VNAV and LPV,

The CNX80 has a baro input -- I have an encoder with 10' resolution. I
believe the plan is for baro VNAV when a GPS signal is unavailable. That
may even be a part of the TSO 146 spec, but I'm not certain of that.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

wrote in message ...
=20
=20
"John R. Copeland" wrote:
=20
Right now, the CNX-80 does not give vertical guidance, but that is
promised in software version 2.0, hopefully to be approved by =
Q3/2004.
That software v2.0 has been in flight test since Q4/2003.
I'm unaware of any box nearer than the CNX-80 to LPV capability.
---JRC---
=20
Most of the modern iron has Baro VNAV which, in addition to being =
authorized in the final approach
segment as primary vertical guidance where VNAV minimums are charted, =
is used extensively for
flying constant angle descents in the segments of an IAP prior to the =
Baro VNAV P-FAF. That's
different that LPV, which can only be used in the final approach =
segment where LPV minimums are
charted, and you have LPV approval.
=20
If the CNX-80 will be able to do both Baro VNAV and LPV, that will be =
very advanced, indeed. Is
that the plan?
=20

I've been curious about the plan for the CNX-80 myself.
It might be my own eagerness making me expect LPV capability.
I've been trying hard to be patient, waiting for FAA approval of v2.0,
whereupon I hope the plans will all become clear to the rest of us.
Or is that hope too optimistic?
---JRC---

"John R. Copeland" wrote:

..

It might be my own eagerness making me expect LPV capability.
I've been trying hard to be patient, waiting for FAA approval of v2.0,
whereupon I hope the plans will all become clear to the rest of us.
Or is that hope too optimistic?
---JRC---

Not if Garmin pushes hard enough. The FAA is responsive to a major company like Garmin, provided the
company pushes hard enough. An example is the very recent certification of the Garmin 1000 for the
Cessna 182/206 and one of the Diamond models.