You're supposed to go missed if you have a RAIM or GPS failure message.
But all the GPS IAP's I've seen have missed approaches that require
use of the GPS to fly correctly (fly to this waypoint, then go to this
other waypoint and hold). So what do you do? Use the GPS to fly the
missed despite the RAIM failure (assuming the whole GPS hasn't gone
belly up)? Call ATC for help?

"xyzzy" > wrote in message
...
>
> You're supposed to go missed if you have a RAIM or GPS failure message.
> But all the GPS IAP's I've seen have missed approaches that require use of
> the GPS to fly correctly (fly to this waypoint, then go to this other
> waypoint and hold). So what do you do? Use the GPS to fly the missed
> despite the RAIM failure (assuming the whole GPS hasn't gone belly up)?
> Call ATC for help?
>

This isn't peculiar to GPS approaches. What do you do on a VOR approach
when the VOR fails and it's needed for the missed approach procedure?

xyzzy > wrote:

> You're supposed to go missed if you have a RAIM or GPS failure message.
> But all the GPS IAP's I've seen have missed approaches that require
> use of the GPS to fly correctly (fly to this waypoint, then go to this
> other waypoint and hold). So what do you do? Use the GPS to fly the
> missed despite the RAIM failure (assuming the whole GPS hasn't gone
> belly up)? Call ATC for help

I have experienced a RAIM failure during a GPS approach, but the GPS was
still able to provide terminal resolution guidance to the missed approach
point. Another time I experienced a complete GPS failure during an
approach (BK KLN-94), but in that case I requested vectors from ATC.

--
Peter
























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The GPS doesn't stop working when you get a RAIM warning. All RAIM
means is the accuracy can't be verified. I have gotten quite a few RAIM
messages on my GX55, if not for the warning you would never have known
it. The GPS hums along nicely.



xyzzy wrote:
> You're supposed to go missed if you have a RAIM or GPS failure message.
> But all the GPS IAP's I've seen have missed approaches that require use
> of the GPS to fly correctly (fly to this waypoint, then go to this other
> waypoint and hold). So what do you do? Use the GPS to fly the missed
> despite the RAIM failure (assuming the whole GPS hasn't gone belly up)?
> Call ATC for help?
>

xyzzy wrote:
> You're supposed to go missed if you have a RAIM or GPS failure message.
> But all the GPS IAP's I've seen have missed approaches that require use
> of the GPS to fly correctly (fly to this waypoint, then go to this other
> waypoint and hold). So what do you do? Use the GPS to fly the missed
> despite the RAIM failure (assuming the whole GPS hasn't gone belly up)?
> Call ATC for help?
>
A Raim Warning you should still have GPS and can execute the missed. I
have had a complete failure of the GPS just past the FAF and in the
soup. Approach had just told me to go to advisory. My action was to
level off, hit the switch back to approach, advise them of the situation
and request a vector, a the while holding the final approach course. I
knew I would be safe for a period of time on that course.

ATC then told me I could descend 300 more feet, the ATIS had reported
the ceiling should be 300 feet below me so I took a chance and broke out
with the center line of the runway straight ahead of me and could make a
normal landing.

Scott

--
--------------------
Scott F. Migaldi
CP-ASEL-IA
N8116B

PADI MI-150972
Join the PADI Instructor Yahoo Group
http://groups.yahoo.com/group/PADI-Instructors/

--------------------

xyzzy > wrote in :

> You're supposed to go missed if you have a RAIM or GPS failure message.
> But all the GPS IAP's I've seen have missed approaches that require
> use of the GPS to fly correctly (fly to this waypoint, then go to this
> other waypoint and hold). So what do you do? Use the GPS to fly the
> missed despite the RAIM failure (assuming the whole GPS hasn't gone
> belly up)? Call ATC for help?

As others have said, the GPS will still work, you just won't be assured of
enough accuracy for the approach at MDA. You will still have plenty of
accuracy for holding at the MAP holding fix, though. For holding you just
need to be in the general vicinity. Also, you can continue the approach if
the RAIM warning happens after the FAF. The RAIM warning means that there
is a prediction of lower accuracy sometime in the future, probably after
you finish the approach, unless your groundspeed is very slow.

--
Regards,

Stan

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." B. Franklin

"Stan Gosnell" > wrote in message
...
> xyzzy > wrote in :
>
>> You're supposed to go missed if you have a RAIM or GPS failure message.
>> But all the GPS IAP's I've seen have missed approaches that require
>> use of the GPS to fly correctly (fly to this waypoint, then go to this
>> other waypoint and hold). So what do you do? Use the GPS to fly the
>> missed despite the RAIM failure (assuming the whole GPS hasn't gone
>> belly up)? Call ATC for help?
>>
>
> As others have said, the GPS will still work, you just won't be assured of
> enough accuracy for the approach at MDA.
>

So what is meant by a GPS failure message then?

Stan Gosnell > wrote:

> As others have said, the GPS will still work, you just won't be assured of
> enough accuracy for the approach at MDA. You will still have plenty of
> accuracy for holding at the MAP holding fix, though.

I think you mean only when there is a RAIM warning does the GPS still
provide course navigation. When I experienced a GPS error message with the
KLN-94, the GPS was completely useless and needed to be recycled before it
began working again, much like a computer hard-boot.

It is also worth noting that this particular error only happened this one
time with the KLN94. Having a few hundred hours now behind a GNS430, I
have never experienced any type of GPS system error or RAIM error with the
Garmin.

--
Peter
























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Peter R. wrote:

> Stan Gosnell > wrote:
>
>
>>As others have said, the GPS will still work, you just won't be assured of
>>enough accuracy for the approach at MDA. You will still have plenty of
>>accuracy for holding at the MAP holding fix, though.
>
>
> I think you mean only when there is a RAIM warning does the GPS still
> provide course navigation. When I experienced a GPS error message with the
> KLN-94, the GPS was completely useless and needed to be recycled before it
> began working again, much like a computer hard-boot.
>
> It is also worth noting that this particular error only happened this one
> time with the KLN94. Having a few hundred hours now behind a GNS430, I
> have never experienced any type of GPS system error or RAIM error with the
> Garmin.
>
The new RNAV (RNP) criteria presume a complete loss of GPS for the
missed approach. If the airspace/obstacle environment will permit a
heading or track to a VOR missed approach in the event of loss of GPS,
then no backup is required. If the missed approach areas are too tight
then dual or triple IRUs are required.

With the present RNAV (GPS) approaches the presumption is that flying
headings will get you out of the woods until you can either get a vector
or receive a VOR. There is some risk with this presumption.

On Sat, 10 Sep 2005 17:30:27 GMT, Tim > wrote:


>>
>The new RNAV (RNP) criteria presume a complete loss of GPS for the
>missed approach. If the airspace/obstacle environment will permit a
>heading or track to a VOR missed approach in the event of loss of GPS,
>then no backup is required. If the missed approach areas are too tight
>then dual or triple IRUs are required.
>

Where is that requirement spelled out for Part 91 operators using GPS
(single-sensor)? I don't see it in AC90-100, but that does not deal with
missed approaches.


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

Ron Rosenfeld wrote:
> On Sat, 10 Sep 2005 17:30:27 GMT, Tim > wrote:
>
>
>
>>The new RNAV (RNP) criteria presume a complete loss of GPS for the
>>missed approach. If the airspace/obstacle environment will permit a
>>heading or track to a VOR missed approach in the event of loss of GPS,
>>then no backup is required. If the missed approach areas are too tight
>>then dual or triple IRUs are required.
>>
>
>
> Where is that requirement spelled out for Part 91 operators using GPS
> (single-sensor)? I don't see it in AC90-100, but that does not deal with
> missed approaches.
>
>
> Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

First, you can't use the new procedures at all unless you receive a
letter of authorization from your FSDO. That is a requirement of
"SAAAR." Part of that qualification requirement is to understand the
requirements of each RNAV (RNP) SAAAR SIAP. There is currently in
coordination such a "dual-thread" IAP for KSUN. The missed approach
reads in part, "RNP required." Implicit in that is the ability to
maintain RNP with loss of GPS. That can only be done with an IRU platform.

On Mon, 12 Sep 2005 11:49:41 GMT, wrote:

>Ron Rosenfeld wrote:
>> On Sat, 10 Sep 2005 17:30:27 GMT, Tim > wrote:
>>
>>
>>
>>>The new RNAV (RNP) criteria presume a complete loss of GPS for the
>>>missed approach. If the airspace/obstacle environment will permit a
>>>heading or track to a VOR missed approach in the event of loss of GPS,
>>>then no backup is required. If the missed approach areas are too tight
>>>then dual or triple IRUs are required.
>>>
>>
>>
>> Where is that requirement spelled out for Part 91 operators using GPS
>> (single-sensor)? I don't see it in AC90-100, but that does not deal with
>> missed approaches.
>>
>>
>> Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)
>
>First, you can't use the new procedures at all unless you receive a
>letter of authorization from your FSDO. That is a requirement of
>"SAAAR." Part of that qualification requirement is to understand the
>requirements of each RNAV (RNP) SAAAR SIAP. There is currently in
>coordination such a "dual-thread" IAP for KSUN. The missed approach
>reads in part, "RNP required." Implicit in that is the ability to
>maintain RNP with loss of GPS. That can only be done with an IRU platform.

Ah, I think we are talking two different things. I've been thinking, and
reading about, the RNAV SID's and STAR's. You're writing about SIAP's.

I can maintain the RNP with GPS, but don't have any backup for that.

Where can I read about these new RNAV SIAP's? Will they also require
radius-to-fix legs?

What is "SAAAR"?


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

On Mon, 12 Sep 2005 17:49:51 -0400, Ron Rosenfeld >
wrote:

>On Mon, 12 Sep 2005 11:49:41 GMT, wrote:
>
>>Ron Rosenfeld wrote:
>>> On Sat, 10 Sep 2005 17:30:27 GMT, Tim > wrote:
>>>
>>>
>>>
>>>>The new RNAV (RNP) criteria presume a complete loss of GPS for the
>>>>missed approach. If the airspace/obstacle environment will permit a
>>>>heading or track to a VOR missed approach in the event of loss of GPS,
>>>>then no backup is required. If the missed approach areas are too tight
>>>>then dual or triple IRUs are required.
>>>>
>>>
>>>
>>> Where is that requirement spelled out for Part 91 operators using GPS
>>> (single-sensor)? I don't see it in AC90-100, but that does not deal with
>>> missed approaches.
>>>
>>>
>>> Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)
>>
>>First, you can't use the new procedures at all unless you receive a
>>letter of authorization from your FSDO. That is a requirement of
>>"SAAAR." Part of that qualification requirement is to understand the
>>requirements of each RNAV (RNP) SAAAR SIAP. There is currently in
>>coordination such a "dual-thread" IAP for KSUN. The missed approach
>>reads in part, "RNP required." Implicit in that is the ability to
>>maintain RNP with loss of GPS. That can only be done with an IRU platform.
>
>Ah, I think we are talking two different things. I've been thinking, and
>reading about, the RNAV SID's and STAR's. You're writing about SIAP's.
>
>I can maintain the RNP with GPS, but don't have any backup for that.
>
>Where can I read about these new RNAV SIAP's? Will they also require
>radius-to-fix legs?
>
>What is "SAAAR"?
>
>
>Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)


Never mind. In today's Jepp update, there is a discussion of these new
SIAP's and it answers all of my above questions.


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

Ron Rosenfeld wrote:

> On Mon, 12 Sep 2005 11:49:41 GMT, wrote:
>
>
>>Ron Rosenfeld wrote:
>>
>>>On Sat, 10 Sep 2005 17:30:27 GMT, Tim > wrote:
>>>
>>>
>>>
>>>
>>>>The new RNAV (RNP) criteria presume a complete loss of GPS for the
>>>>missed approach. If the airspace/obstacle environment will permit a
>>>>heading or track to a VOR missed approach in the event of loss of GPS,
>>>>then no backup is required. If the missed approach areas are too tight
>>>>then dual or triple IRUs are required.
>>>>
>>>
>>>
>>>Where is that requirement spelled out for Part 91 operators using GPS
>>>(single-sensor)? I don't see it in AC90-100, but that does not deal with
>>>missed approaches.
>>>
>>>
>>>Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)
>>
>>First, you can't use the new procedures at all unless you receive a
>>letter of authorization from your FSDO. That is a requirement of
>>"SAAAR." Part of that qualification requirement is to understand the
>>requirements of each RNAV (RNP) SAAAR SIAP. There is currently in
>>coordination such a "dual-thread" IAP for KSUN. The missed approach
>>reads in part, "RNP required." Implicit in that is the ability to
>>maintain RNP with loss of GPS. That can only be done with an IRU platform.
>
>
> Ah, I think we are talking two different things. I've been thinking, and
> reading about, the RNAV SID's and STAR's. You're writing about SIAP's.
>
> I can maintain the RNP with GPS, but don't have any backup for that.
>
> Where can I read about these new RNAV S

There is an 90 series AC in final draft phase.

IAP's? Will they also require
> radius-to-fix legs?

Not always. The KSUN procedure presently on the FAA coordination site
does not use RF legs but it requires RNP for the missed/extraction.
>
> What is "SAAAR"?
>
Special Aircraft and Aircrew Authorization Required, same as CAT II/III
>
> Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

The draft language that will likely become official:

This is one (of many) reasons these RNP procedures are SAAAR. This will
be addressed in the aircrew training. AC 90-RNP SAAAR (still up for
approval signature and number assignment), Appendix 1, paragraph 2c,
does start the ball rolling with:

c. RNP missed approach. At designated locations, the
airspace or obstacle environment will require precise RNP capability
during a missed approach from anywhere on the procedure. At these
designated locations the reliability of the navigation system has to
be very high to conduct the approach. Operation on these designated
approaches typically requires redundant equipment, as no single
point of failure can cause loss of RNP capability. An example of a
missed approach requiring RNP is shown in Figure 5, as indicated in the
notes section of the chart.

Then in Appendix 5, Operational Considerations, paragraph 2o, you have
the "Go-Around or Missed Approach" guidance:

o. Go-Around or Missed Approach.

(1) Procedures that do not require RNP Missed Approach.
Where possible, the missed approach does not require precise RNP
guidance. The missed approach portion of these procedures is similar to
a missed approach of an RNAV (GPS) approach.

(2) Procedures that require RNP missed approach. Where
necessary, RNP values less than RNP-1 will be used in the missed
approach or precise RNP capability may be necessary in the event of
a go-around before the decision altitude. Since not all aircraft
have this capability, flight crews must be aware of whether or not
they can conduct these procedures. For those that can conduct it, a
different set of equipment or procedures may be required. In many
aircraft a change in lateral navigation capability may exist upon
actuation of Take-off/Go-around (TOGA). In most aircraft,
the autopilot and flight director disengage from the LNAV guidance, and
the flight director reverts to track-hold derived from the inertial
system. Flight crew procedures and training must address the need to
minimize the lateral deviation from the published missed approach
procedure. LNAV guidance to the autopilot and flight director
should be re-engaged as quickly as possible.

(3) The flight crew procedures and training must address the
impact on navigation capability and flight guidance if the pilot
initiates a go-around while the aircraft is in a turn.

On Wed, 14 Sep 2005 19:22:04 GMT, wrote:

>
>The draft language that will likely become official:
>
>This is one (of many) reasons these RNP procedures are SAAAR. This will
>be addressed in the aircrew training. AC 90-RNP SAAAR (still up for
>approval signature and number assignment), Appendix 1, paragraph 2c,
>does start the ball rolling with:
>
> c. RNP missed approach. At designated locations, the
>airspace or obstacle environment will require precise RNP capability
>during a missed approach from anywhere on the procedure. At these
>designated locations the reliability of the navigation system has to
>be very high to conduct the approach. Operation on these designated
> approaches typically requires redundant equipment, as no single
>point of failure can cause loss of RNP capability. An example of a
>missed approach requiring RNP is shown in Figure 5, as indicated in the
>notes section of the chart.
>
>Then in Appendix 5, Operational Considerations, paragraph 2o, you have
>the "Go-Around or Missed Approach" guidance:
>
> o. Go-Around or Missed Approach.
>
> (1) Procedures that do not require RNP Missed Approach.
>Where possible, the missed approach does not require precise RNP
>guidance. The missed approach portion of these procedures is similar to
>a missed approach of an RNAV (GPS) approach.
>
> (2) Procedures that require RNP missed approach. Where
>necessary, RNP values less than RNP-1 will be used in the missed
>approach or precise RNP capability may be necessary in the event of
>a go-around before the decision altitude. Since not all aircraft
>have this capability, flight crews must be aware of whether or not
>they can conduct these procedures. For those that can conduct it, a
>different set of equipment or procedures may be required. In many
>aircraft a change in lateral navigation capability may exist upon
>actuation of Take-off/Go-around (TOGA). In most aircraft,
>the autopilot and flight director disengage from the LNAV guidance, and
>the flight director reverts to track-hold derived from the inertial
>system. Flight crew procedures and training must address the need to
>minimize the lateral deviation from the published missed approach
>procedure. LNAV guidance to the autopilot and flight director
>should be re-engaged as quickly as possible.
>
> (3) The flight crew procedures and training must address the
>impact on navigation capability and flight guidance if the pilot
>initiates a go-around while the aircraft is in a turn.
>

Thank you for that information.


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