That's gotta be wrong

We had a local safety counsellor give us a seminar on GPS and he said
something that seems pretty ridiculous. I understand that when you're
using GPS, if you file an alternate, it has to have non-GPS approaches in
case GPS isn't working in the area or your own GPS unit is T/U. And he
wasn't entirely clear, but it makes sense to me that if you get to your
alternate and your GPS is working fine, sure you can shoot the GPS
approach rather than the non-GPS approach. But then he said something
that makes no sense to me: he said that if you have to go missed at your
alternate, you're not allowed to use GPS to navigate the missed approach
procedure. Please tell me that he was misinterpreting a rule that said
you have to be *able* to navigate the missed approach procedure without
GPS, but you don't *have* to do so. So, for instance, if the missed
approach involves holding at a NDB, you have to have a ADF in the plane in
case GPS isn't working, but if the GPS is there and working you can use
it?

--
Paul Tomblin http://xcski.com/blogs/pt/
Revenge is an integral part of forgiving and forgetting.
-- The BOFH

Paul Tomblin wrote:
We had a local safety counsellor give us a seminar on GPS and he said
something that seems pretty ridiculous. I understand that when you're
using GPS, if you file an alternate, it has to have non-GPS approaches in
case GPS isn't working in the area or your own GPS unit is T/U. And he
wasn't entirely clear, but it makes sense to me that if you get to your
alternate and your GPS is working fine, sure you can shoot the GPS
approach rather than the non-GPS approach. But then he said something
that makes no sense to me: he said that if you have to go missed at your
alternate, you're not allowed to use GPS to navigate the missed approach
procedure. Please tell me that he was misinterpreting a rule that said
you have to be *able* to navigate the missed approach procedure without
GPS, but you don't *have* to do so. So, for instance, if the missed
approach involves holding at a NDB, you have to have a ADF in the plane in
case GPS isn't working, but if the GPS is there and working you can use
it?

The restriction applies to TSO C129 navigators like e.g. the Garmin 430/530. It
doesn't apply to TSOC146 navigators like e.g. the Garmin GNS480.

The restriction is on what may be *filed* as an alternate airport. There is no
restriction on what approaches are actually flown, or how you navigate.

You are correct. The safety counsellor is confused.

Most GPS navigators are TSO C 129 except for the CNS 480.

129 units are considered secondary navigation devices.

The consequence is that you must have VHF navigation for
an alternate and pick an alternate that is not GPS-only for
approaches. BTW, that is why you still have to do your vor
checks even tho you nav by GPS everywhere.

Donno about that missed approach business... haven't heard that
one.

Bill Hale

I was late to the seminar, and didn't hear that part, so I might be wrong
here, but what he might be thinking is that the GPS, at least the C129 GPS's
don't sequence automatically to the missed approach point, you have to do it
yourself. Other than that, I looked at the AIM, and as long as you have the
non-GPS equipment required to fly the missed, and everything is working, it
looks to me as if you can use the GPS to actually fly it.

Basically, it looks like the rule for approaches is that you can use the GPS
for anything as long as you don't need it. If it is your only source of
navigation, then you can't legally use it for the approach. Enroute, it is a
little more relaxed, you can substitute the GPS for an ADF or DME under some
circumstances.

Just my opinion, I could be wrong.
Brad


"Paul Tomblin" wrote in message
...
We had a local safety counsellor give us a seminar on GPS and he said
something that seems pretty ridiculous. I understand that when you're
using GPS, if you file an alternate, it has to have non-GPS approaches in
case GPS isn't working in the area or your own GPS unit is T/U. And he
wasn't entirely clear, but it makes sense to me that if you get to your
alternate and your GPS is working fine, sure you can shoot the GPS
approach rather than the non-GPS approach. But then he said something
that makes no sense to me: he said that if you have to go missed at your
alternate, you're not allowed to use GPS to navigate the missed approach
procedure. Please tell me that he was misinterpreting a rule that said
you have to be *able* to navigate the missed approach procedure without
GPS, but you don't *have* to do so. So, for instance, if the missed
approach involves holding at a NDB, you have to have a ADF in the plane in
case GPS isn't working, but if the GPS is there and working you can use
it?

--
Paul Tomblin http://xcski.com/blogs/pt/
Revenge is an integral part of forgiving and forgetting.
-- The BOFH

Does anyone know if the upcoming (someday) WAAS upgrade to the GARMIN
430/530 will make it TSO 146a compliant unit?

Brad
"Bill" wrote in message
oups.com...
Most GPS navigators are TSO C 129 except for the CNS 480.

129 units are considered secondary navigation devices.

The consequence is that you must have VHF navigation for
an alternate and pick an alternate that is not GPS-only for
approaches. BTW, that is why you still have to do your vor
checks even tho you nav by GPS everywhere.

Donno about that missed approach business... haven't heard that
one.

Bill Hale

On Sun, 27 Nov 2005 15:20:54 GMT, "Brad Salai"
wrote:

I was late to the seminar, and didn't hear that part, so I might be wrong
here, but what he might be thinking is that the GPS, at least the C129 GPS's
don't sequence automatically to the missed approach point, you have to do it
yourself. Other than that, I looked at the AIM, and as long as you have the
non-GPS equipment required to fly the missed, and everything is working, it
looks to me as if you can use the GPS to actually fly it.

That's my understanding too - the substitution rules are only for
planning an alternate, but have no bearing on what you do (assuming
everything is working and no RAIM issues) once you're in the air.

You may have reduced your chances for an answer when you asked,
"Does anyone know...".
Yes, the intent is for the 430/530 units to satisfy TSO-C146a eventually,
but we'll *know* it when we see it happen.
Let's hope the schedule doesn't slip any further. :-/

"Brad Salai" wrote in message ...
Does anyone know if the upcoming (someday) WAAS upgrade to the GARMIN
430/530 will make it TSO 146a compliant unit?

Brad
"Bill" wrote in message
oups.com...
Most GPS navigators are TSO C 129 except for the CNS 480.

129 units are considered secondary navigation devices.

The consequence is that you must have VHF navigation for
an alternate and pick an alternate that is not GPS-only for
approaches. BTW, that is why you still have to do your vor
checks even tho you nav by GPS everywhere.

Donno about that missed approach business... haven't heard that
one.

Bill Hale

The reason for a non-GPS system at the alternate is that if there is a
GPS RAIM outage it probably affects your alternate as well. Hence a
different system. That suggests that ANY GPS navigation is not
allowed. Of course if the original GPS outage clears then you should
be fine. My opinion of course.

I also believe that this restrction is not in place if you use WAAS
because WAAS provides the required integrity.

Ron Lee

Paul Tomblin wrote:

We had a local safety counsellor give us a seminar on GPS and he said
something that seems pretty ridiculous. I understand that when you're
using GPS, if you file an alternate, it has to have non-GPS approaches in
case GPS isn't working in the area or your own GPS unit is T/U. And he
wasn't entirely clear, but it makes sense to me that if you get to your
alternate and your GPS is working fine, sure you can shoot the GPS
approach rather than the non-GPS approach. But then he said something
that makes no sense to me: he said that if you have to go missed at your
alternate, you're not allowed to use GPS to navigate the missed approach
procedure. Please tell me that he was misinterpreting a rule that said
you have to be *able* to navigate the missed approach procedure without
GPS, but you don't *have* to do so. So, for instance, if the missed
approach involves holding at a NDB, you have to have a ADF in the plane in
case GPS isn't working, but if the GPS is there and working you can use
it?

I posted a reply to this before but it got lost in the bit bucket.

He is speaking of an overlay approach and he is correct, technically you
must have the underlying equipment available. By the time you get to
the alternate your options are quite limited in any case.

Dave Butler wrote:

Paul Tomblin wrote:

We had a local safety counsellor give us a seminar on GPS and he said
something that seems pretty ridiculous. I understand that when you're
using GPS, if you file an alternate, it has to have non-GPS approaches in
case GPS isn't working in the area or your own GPS unit is T/U. And he
wasn't entirely clear, but it makes sense to me that if you get to your
alternate and your GPS is working fine, sure you can shoot the GPS
approach rather than the non-GPS approach. But then he said something
that makes no sense to me: he said that if you have to go missed at your
alternate, you're not allowed to use GPS to navigate the missed approach
procedure. Please tell me that he was misinterpreting a rule that said
you have to be *able* to navigate the missed approach procedure without
GPS, but you don't *have* to do so. So, for instance, if the missed
approach involves holding at a NDB, you have to have a ADF in the
plane in
case GPS isn't working, but if the GPS is there and working you can use
it?


The restriction applies to TSO C129 navigators like e.g. the Garmin
430/530. It doesn't apply to TSOC146 navigators like e.g. the Garmin
GNS480.

The restriction is on what may be *filed* as an alternate airport. There
is no restriction on what approaches are actually flown, or how you
navigate.

You are correct. The safety counsellor is confused.

No, he is not if he says you can use the GPS if it is still working, but
you have to have the overlay ground equipment available in case the GPS
goes TA.