Instrument approach OTS components
#21
Gets Weekends Off
Joined APC: Apr 2007
Posts: 867
REF VOR RW08 scenario: If you're enroute when you go NORDO, you might not be with your final sector or might not have received the approach clearance. So, the likelihood of an alternate MA being received is slim. Unless there is a published FDC NOTAM with an alternate MA procedure, for planning purposes, you'd need another IAP.
The OP wrote about an ILS with an inop VOR for the missed approach hold waypoint. In that case, if so equipped, an IFR GPS could be used for the MA segment.
REF GPS overlay: there's an NPRM "out there" and I can't find it right now, but any how, it addresses the use of (proposes allowing) an IFR GPS for a non-overlay IAP during the final segment.
The OP wrote about an ILS with an inop VOR for the missed approach hold waypoint. In that case, if so equipped, an IFR GPS could be used for the MA segment.
REF GPS overlay: there's an NPRM "out there" and I can't find it right now, but any how, it addresses the use of (proposes allowing) an IFR GPS for a non-overlay IAP during the final segment.
#22
if you have an fms or a gps, the vor will still be in the database even if it's been destroyed, as in the previous example, so i assume it would be fine to use. Or ask for alternate missed approach instructions before beginning the approach. don't rule the whole approach out just b/c the vor is ots, it might still be perfectly safe to fly.
I didn't quite understand the sentence bolded above, but actually based on different circumstance and more of a technicality. I asked the question around the office and some agreed with the statement above. A little more research though from the group revealed two sources though that would contradict the notion that you could legally fly the (using the given example of kjvy and abb) vor rwy 18 approach using the 'overlay' philosophy.
First from the faa's gnss q&as:
(#21) gnss frequently asked questions - waas
q. I have heard about flying an “overlay” approach, and that it is basically flying a vor or other approach, but using the gps instead of the vor or adf. Can i just use the gps instead of the vor?
A. no. Overlay approaches can use gps instead of the primary designated navigational aid, but the approach must be designated for gps and be in the current aircraft database. For example, it must say “vor or gps rwy 16.” you cannot just use gps in lieu of vor, automatic direction finder (adf) or other navigational source naming the approach. You can, however, use gps to determine waypoints during the approach.
and then again in the aim (para: 1-1-19, pg 1-1-32)
g. Gps approach procedures
as the production of stand−alone gps approaches has progressed, many of the original overlay
approaches have been replaced with stand−alone procedures specifically designed for use by gps
systems. The title of the remaining gps overlay procedures has been revised on the approach chart to “or gps” (e.g., vor or gps rwy 24). therefore, all the approaches that can be used by gps now contain “gps” in the title (e.g., “vor or gps rwy 24,”“gps rwy 24,” or “rnav (gps) rwy 24”). During these gps approaches, underlying ground based navaids are not required to be operational and associated aircraft avionics need not be installed, operational, turned on or monitored (monitoring of the underlying approach is suggested when equipment is available and functional). Existing overlay approaches may be requested using the gps title, such as “gps rwy 24” for the vor or gps rwy 24.
Note
any required alternate airport must have an approved instrument approach procedure other than gps that is anticipated to be operational and available at the estimated time of arrival, and which the aircraft is equipped to fly.
therefore, technically the vor rwy 18 into kjvy could not be legally flown even if the facility was in the database unless the approach plate included the gps in the title (e.g. Vor or gps rwy 18). As that co-worker pointed out though, why would they do that when there is already a stand-alone gps approach to rwy 18 (the standard t configured straight-in).
Thanks again for bringing up such a discussion item.
What say the group?
Usmcflyr
The OP's example is an ILS approach, so only the ILS is required in order to execute the final approach segment. The failed VOR in question is NOT required to execute the final approach segment, so the references you quoted would not apply. The failed VOR is only required in order to execute the Missed Approach procedure.
i agree 100% with usmcflyr (especially since he's quoting the book).
Unless other means are specified on the iap, in an notam, or verbally by atc, you need all required navaids. Atc might be able to give you an alternate missed, but they probably can't just waive a required navaid otherwise.
You can only use gps where published.
This applies to not only the obvious primary navaids but also to missed navaids and things like cross-radials which do not have a published alternate means. Would not apply to a step-down cross-radial on the non-precision if you are doing the ils, only what's required for the procedure you execute.
ref vor rw08 scenario: If you're enroute when you go nordo, you might not be with your final sector or might not have received the approach clearance. So, the likelihood of an alternate ma being received is slim. Unless there is a published fdc notam with an alternate ma procedure, for planning purposes, you'd need another iap.
Back to the OP's original question. Only the ILS is required to fly the Final Approach portion of an approach titled ILS RWY XX. You may navigate to the Final Approach segment by any number of means, or you may receive radar vectors to the Final Approach segment. You must have SOME means to execute the Missed Approach segment. That may mean substituting a different procedure by NOTAM or by clearance from ATC, or it may involve using a GPS navigation system to determine the position and configuration of the published NAVAID.
In short, the answer is, "Yes, IF ..."
.
#23
Since it's very common for ATC to vector you off the missed almost immediately if you do miss on an ILS, what about just coordinating for alternate MAP instructions prior to commencing the approach? Then the OTS VOR isn't needed.
Legal?
Legal?
#24
Gets Weekends Off
Joined APC: Jul 2013
Posts: 459
It also depends on how the notam is written. If it's ILS ABC NA, then it's not authorized. It'll usually have a reason. If is VOR XXX OTS, and it effects the approach/missed approach it may say ILS ABC NA except for aircraft equipped with RNAV. If there isn't a conditional statement, then query ATC and see what they say. In any case, if there's a question, better safe than sorry.
Another one that comes up, especially in some newer aircraft is an approach where an ADF is required. Some newer aircraft don't even have ADFs, in which case RNAV can be used to identify the fix.
Another one that comes up, especially in some newer aircraft is an approach where an ADF is required. Some newer aircraft don't even have ADFs, in which case RNAV can be used to identify the fix.
#25
Gets Weekends Off
Joined APC: Jul 2005
Posts: 245
From another thread:
AIM, 1-1-19 g.)
g. GPS Approach Procedures
As the production of stand−alone GPS approaches has progressed, many of the original overlay approaches have been replaced with stand−alone procedures specifically designed for use by GPS systems. The title of the remaining GPS overlay procedures has been revised on the approach chart to “or GPS” (e.g., VOR or GPS RWY 24). Therefore, all the approaches that can be used by GPS now contain “GPS” in the title (e.g., “VOR or GPS RWY 24,” “GPS RWY 24,” or “RNAV (GPS) RWY 24”). During these GPS approaches, underlying ground− based NAVAIDs are not required to be operational and associated aircraft avionics need not be installed, operational, turned on or monitored (monitoring of the underlying approach is suggested when equip-ment is available and functional).
If the approach has NDB in the title only, then the navaid must be functioning and GPS cannot be used as substitute means of navigation. 90-94 was rescinded in 2009.
If your company has Op Spec C300, then you can use GPS as a substitute means, even if the underlying navaid is inop.
There is also a current notice regarding C300 removing the restriction to have WAAS if the approach is to be used as an alternate.
AIM, 1-1-19 g.)
g. GPS Approach Procedures
As the production of stand−alone GPS approaches has progressed, many of the original overlay approaches have been replaced with stand−alone procedures specifically designed for use by GPS systems. The title of the remaining GPS overlay procedures has been revised on the approach chart to “or GPS” (e.g., VOR or GPS RWY 24). Therefore, all the approaches that can be used by GPS now contain “GPS” in the title (e.g., “VOR or GPS RWY 24,” “GPS RWY 24,” or “RNAV (GPS) RWY 24”). During these GPS approaches, underlying ground− based NAVAIDs are not required to be operational and associated aircraft avionics need not be installed, operational, turned on or monitored (monitoring of the underlying approach is suggested when equip-ment is available and functional).
If the approach has NDB in the title only, then the navaid must be functioning and GPS cannot be used as substitute means of navigation. 90-94 was rescinded in 2009.
If your company has Op Spec C300, then you can use GPS as a substitute means, even if the underlying navaid is inop.
There is also a current notice regarding C300 removing the restriction to have WAAS if the approach is to be used as an alternate.
#26
Gets Weekends Off
Joined APC: Jul 2005
Posts: 245
Default
There is a difference between substitute means of navigation and alternate means of navigation.
Again from the AIM:
a. Discussion. This paragraph sets forth policy concerning the operational use of RNAV equipment for the following applications within the National Airspace System (NAS):
1. As a substitute means of navigation guidance when a VOR, NDB, DME, or compass locator facility is out-of-service (that is, the navaid information is not available); an aircraft is not equipped with conventional equipment such as ADF or DME; or the conventional equipment such as ADF or DME on an aircraft is not operational. For example, if equipped with a suitable RNAV system, a pilot might hold over an out-of-service NDB.
2. As an alternate means for navigation guidance when a VOR, NDB, DME, or compass locator facility is operational, such that the pilot can revert to the underlying guidance, as necessary, but does not normally monitor the underlying aid. For example, if equipped with a suitable RNAV system, a pilot might fly a procedure or route based on operational VOR using RNAV equipment but not monitor the VOR.
Further in the section it states:
c. Allowable Operations. Subject to the requirements in this paragraph, operators may use an RNAV system for the following operations:
1. Determine aircraft position over a VOR, NDB, compass locator, or DME fix.
2. Determine the aircraft position over a named fix defined by a VOR course, NDB bearing, or compass locator bearing crossing a VOR or localizer course.
3. Navigate to or from a VOR, NDB, or compass locator. For example, a pilot might proceed direct to a VOR or navigate on a segment of a departure procedure. However, pilots may not substitute for the navigation aid providing lateral guidance for the final approach segment. This restriction does not refer to instrument approach procedures with "or GPS" in the title when using GPS or WAAS.
4. Hold over a VOR, NDB, compass locator, or DME fix.
5. Fly a DME arc.
These allowances do not include navigation on localizer-based courses (including localizer back-course guidance).
This is the same intent from AC 90-108:
8b. Substitution on a Final Approach Segment. Substitution for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment.
8c. Lateral Navigation on LOC-Based Courses. Lateral navigation on LOC-based courses (including LOC back-course guidance) without reference to raw LOC data.
From this is were Boeing derives their guidance for raw data requirements. As an example, this is from the 747 FCTM:
Raw Data Monitoring Requirements:
During localizer-based approaches; LOC, LOC-BC, LDA, SDF, and IGS, applicable raw data must be monitored throughout the approach.
During non-localizer based approaches where the FMC is used for course or path tracking (VOR, TACAN, NDB, RNAV, GPS, etc.), monitoring raw data is recommended, if available. For airplanes with two operational FMCs, two IRSs and two GPS receivers (or two DME receivers if GPS updating is not available), or if the FMC is RNP/ANP capable, raw data monitoring is not required.
For VOR, NDB etc. approaches without GPS in the title, you can use GPS as an alternate means of navigation for the final segment.
But you can't use it as a substitute means of navigation for the final segment, unless the operator has Ops Spec C300 approval.
There is a difference between substitute means of navigation and alternate means of navigation.
Again from the AIM:
a. Discussion. This paragraph sets forth policy concerning the operational use of RNAV equipment for the following applications within the National Airspace System (NAS):
1. As a substitute means of navigation guidance when a VOR, NDB, DME, or compass locator facility is out-of-service (that is, the navaid information is not available); an aircraft is not equipped with conventional equipment such as ADF or DME; or the conventional equipment such as ADF or DME on an aircraft is not operational. For example, if equipped with a suitable RNAV system, a pilot might hold over an out-of-service NDB.
2. As an alternate means for navigation guidance when a VOR, NDB, DME, or compass locator facility is operational, such that the pilot can revert to the underlying guidance, as necessary, but does not normally monitor the underlying aid. For example, if equipped with a suitable RNAV system, a pilot might fly a procedure or route based on operational VOR using RNAV equipment but not monitor the VOR.
Further in the section it states:
c. Allowable Operations. Subject to the requirements in this paragraph, operators may use an RNAV system for the following operations:
1. Determine aircraft position over a VOR, NDB, compass locator, or DME fix.
2. Determine the aircraft position over a named fix defined by a VOR course, NDB bearing, or compass locator bearing crossing a VOR or localizer course.
3. Navigate to or from a VOR, NDB, or compass locator. For example, a pilot might proceed direct to a VOR or navigate on a segment of a departure procedure. However, pilots may not substitute for the navigation aid providing lateral guidance for the final approach segment. This restriction does not refer to instrument approach procedures with "or GPS" in the title when using GPS or WAAS.
4. Hold over a VOR, NDB, compass locator, or DME fix.
5. Fly a DME arc.
These allowances do not include navigation on localizer-based courses (including localizer back-course guidance).
This is the same intent from AC 90-108:
8b. Substitution on a Final Approach Segment. Substitution for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment.
8c. Lateral Navigation on LOC-Based Courses. Lateral navigation on LOC-based courses (including LOC back-course guidance) without reference to raw LOC data.
From this is were Boeing derives their guidance for raw data requirements. As an example, this is from the 747 FCTM:
Raw Data Monitoring Requirements:
During localizer-based approaches; LOC, LOC-BC, LDA, SDF, and IGS, applicable raw data must be monitored throughout the approach.
During non-localizer based approaches where the FMC is used for course or path tracking (VOR, TACAN, NDB, RNAV, GPS, etc.), monitoring raw data is recommended, if available. For airplanes with two operational FMCs, two IRSs and two GPS receivers (or two DME receivers if GPS updating is not available), or if the FMC is RNP/ANP capable, raw data monitoring is not required.
For VOR, NDB etc. approaches without GPS in the title, you can use GPS as an alternate means of navigation for the final segment.
But you can't use it as a substitute means of navigation for the final segment, unless the operator has Ops Spec C300 approval.
#27
Disinterested Third Party
Joined APC: Jun 2012
Posts: 5,926
It's not uncommon to be cleared for an approach and to be given a missed approach procedure with the clearance that differs from published. An alternate missed might be for equipment, traffic, weather, routing, or other reasons.
"Waxahotchi Eight Six Niner is cleared the Danderdoodle two-three ILS, on the missed approach fly runway heading and maintain eight thousand. Upon reaching eight thousand, direct BABUU and hold as published."
Absolutely a procedure may be issued when components of that procedure are not operative. An ILS that has an inoperative glideslope component, for example, may be issued as an ILS approach clearance, even though the glideslope is not operative. Some procedures provide for alternate means of identification of a waypoint (eg, radar in lieu of a DME fix, or in lieu of DME, etc). Others do not.
Where a component of the procedure is not available, alternate compliance may be arranged and disseminated in advance by NOTAM.
#28
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