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Instrument approach OTS components

Old 09-13-2016, 10:36 AM
  #21  
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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.
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Old 09-13-2016, 12:16 PM
  #22  
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Originally Posted by usmcflyr View Post

Originally Posted by planespotta View Post

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.

this is what i like about the forum. The discussion that a seemingly simple question can produce, and the way that it gets people to get back into the books, enhances understanding and safety for all.

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

Interesting, but it doesn't really address the Original Poster's situation and query. Your apparently contradicting citations deal with scenarios where the failed NAVAID is used for the final approach segment of the Instrument Approach Procedure. The TITLE of the IAP will only include the NAVAIDs or components required to execute the final approach portion, not those that may be required to get to the IAF, and not those that may be required to execute the missed approach. The examples you've given deal with a failed VOR that is required to execute the final approach segment, and which is named in the title of the procedure.

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.





Originally Posted by planespotta View Post

completely agree with everything you said. Can't (legally...hehe) fly a vor-8 approach with gps overlay b/c "gps" isn't listed in the title, & why make 2 approaches when 1 would suffice?

The information wasn't wrong, it just wasn't pertinent.

Originally Posted by planespotta View Post

Additionally, however, in the op's example, the vor was what you'd be holding at after you went missed - not the primary navaid for the approach. In this case, if it's ots, why not request alternate missed approach instructions like a heading?

Right. Exactly. Clearance for alternate missed approach instructions would eliminate the need to have a functional VOR.



Originally Posted by rickair7777 View Post

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.

Again, nothing wrong with book quotes if they apply to the question asked. Those don't.



Originally Posted by rickair7777 View Post

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.

It applies ONLY to those NAVAIDs required for the Final Approach Segment, those named in the title of the Instrument Approach Procedure.



Originally Posted by deadstick35 View Post

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.

Well, now you're adding a different dimension to the question, so the answer has to account for the new dimension. The OP asked if it was legal to FLY the approach. Now you're discussing flight planning considerations. You cannot, obviously, coordinate alternate Missed Approach procedures before you ever talk to the Approach Controller, so other provisions must be made. Perhaps it's a NOTAM describing alternate procedures, or perhaps it's the ability to use another navigation system (GPS) to define the point.


Originally Posted by deadstick35 View Post

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.

I believe you are correct.



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 ..."






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Old 09-14-2016, 12:11 PM
  #23  
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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?
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Old 09-14-2016, 06:20 PM
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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.
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Old 09-14-2016, 07:56 PM
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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.
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Old 09-14-2016, 07:58 PM
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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.
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Old 09-14-2016, 11:19 PM
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Originally Posted by captain152 View Post
If you aren't able to fly a published missed from an approach you wouldn't be legal to execute it.
Not true.

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.
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Old 09-15-2016, 09:55 AM
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Originally Posted by captain152 View Post

Keep in mind I don't have a reference for you in the FAR/AIM, but I'm fairly certain everyone here would agree with me.


<Raises hand> Not me!






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