GPS missed approach question

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)