ILS...Still have to identify FAF?

Gucci Pilot

Gucci Pilot

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Gucci Pilot
Haven't been able to find the exact wording on this. Say you are getting vectored for the ILS 21 into Altoona(KAOO) and the Outer Marker is out of service. Can you still legally shoot the approach? You don't have GPS.
 
What is the definition of the FAF on a vertically-guided approach?

Glideslope intercept. Has nothing to do with the marker, DME fix or intersection that is typically collocated for the purposes of the underlying LOC approach.

So yes, you can still fly the approach, barring any company policies to the contrary.

For sake of discussion, consider a typical scenario like that one the Santa Rosa, CA STS ILS OR LOC RWY 32:

http://skyvector.com/files/tpp/1502/pdf/00696IL32.PDF

The LOC FAF is the OM. But the ILS FAF is not, it is actually about 1/3 mile before that, at glideslope intercept at 2000. The OM being out of service wouldn't affect how you fly this approach. (It would, however, remove the check altitude of 1903 at the OM. Well, unless you had DME anyway.)
 
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First, here's the chart:
http://155.178.201.160/d-tpp/1502/00100IL21.PDF

There's no notes or labels saying anything other than an ILS (LOC plus GS) and the usual assumed VOR capability is required to fly this approach. Clearly, the only means to identify the LOC FAF is the OM or an IFR GPS, but since the FAP for an ILS approach is glide slope intercept, you can certainly shoot the approach as ILS without needing to identify passage of the OM. Of course, if the GS quits on you halfway down, you can't revert to LOC without having timing from the OM, but that's rarely an issue.
 
The outer marker has pretty much been optional since I started to fly. It's not the FAF anyhow on an ILS and whatever navigational purpose it has is often supplanted by other means. On the AOO ILS21 it's only real significance is the FAF for the LOC and circling versions of the approach. It is handy to confirm the intercept but not obligatory. Even the Middle Marker was optional. Used to be you raised the minimums by 50' if you didn't have it, but that rule's been gone for over two decades now as well. No MM on this approach anyway.
 
There is no FAF on an ILS approach. There is a final approach point, indicated by a lightning stroke and coincident with glide slope intercept. If your clearance includes something like "..tower at the marker," ask the controller to call the marker for you.

Bob Gardner
 
bobmrg said:
There is no FAF on an ILS approach. There is a final approach point, indicated by a lightning stroke and coincident with glide slope intercept. If your clearance includes something like "..tower at the marker," ask the controller to call the marker for you.
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You can still do that without ATC calling the marker on radar if you read the chart and watch your altimeter. Note in the profile view on this chart the little "3478" at the OM. That means the GS crosses the marker at 3478 MSL. So, if you're on GS, you can make that radio switch at that altitude and tell tower you're "at the marker" with sufficient accuracy for that purpose.
 
RussR said:
What is the definition of the FAF on a vertically-guided approach?
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bobmrg said:
There is no FAF on an ILS approach.
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I never said anything about a FAF. I know what the FAF is on an ILS.

flyingron said:
It's not the FAF anyhow on an ILS and whatever navigational purpose it has is often supplanted by other means.
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What I'm asking is if there is no other means of identifying it.

This is what our Air Force IFR manual says:

False Glideslope Indications. False glideslope indications may be received when the aircraft is not within the depicted area of coverage, or the glide slope power status is in alarm. There is also a chance that aircraft or vehicles parked in the ILS Critical Area may interfere with the glideslope signal. For these reasons, it is essential to confirm glideslope intercept altitudes and expected altitudes as depicted on the IAP. If indications are suspect, transition to localizer procedures or execute a missed approach.
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A pilot was trying to tell me that if you had no way of identifying the LOC FAF(to cross check your altitude on the glideslope) you can't shoot the approach. He showed me one that was identified off the DME of a TACAN. I told him, "it doesn't say DME required anywhere on the chart..."

He had a difference of opinion.

RussR said:
It would, however, remove the check altitude of 1903 at the OM. Well, unless you had DME anyway.
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DME is required for that approach...Granted it is for the missed approach, but still required.
 
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Gucci Pilot said:
A pilot was trying to tell me that if you had no way of identifying the LOC FAF(to cross check your altitude on the glideslope) you can't shoot the approach. He showed me one that was identified off the DME of a TACAN. I told him, "it doesn't say DME required anywhere on the chart..."

He had a difference of opinion.
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As far as the approach about which you asked is concerned, you were right, and he wasn't, and your reason for why was correct.
 
I was trying not to wade into this debate but...
FAR 91.175 said:
(k) ILS components. The basic ground components of an ILS are the localizer, glide slope, outer marker, middle marker, and, when installed for use with Category II or Category III instrument approach procedures, an inner marker. A compass locator or precision radar may be substituted for the outer or middle marker. DME, VOR, or nondirectional beacon fixes authorized in the standard instrument approach procedure or surveillance radar may be substituted for the outer marker. Applicability of, and substitution for, the inner marker for Category II or III approaches is determined by the appropriate part 97 approach procedure, letter of authorization, or operations specification pertinent to the operations.
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And then there's this...
AIM 1-1-9 Instrument Landing System (ILS) said:
2.The ground equipment consists of two highly directional transmitting systems and, along the approach, three (or fewer) marker beacons. The directional transmitters are known as the localizer and glide slope transmitters.
3.The system may be divided functionally into three parts:
(a)Guidance information:localizer, glide slope;
(b)Range information: marker beacon, DME; and
(c)Visual information:approach lights, touchdown and centerline lights, runway lights.
4.Precision radar, or compass locators located at the Outer Marker (OM) or Middle Marker (MM), may be substituted for marker beacons. DME, when specified in the procedure, may be substituted for the OM.


...

e.Distance Measuring Equipment (DME)
1.When installed with the ILS and specified in the approach procedure, DME may be used:
(a)In lieu of the OM;

...

f.Marker Beacon
1.ILS marker beacons have a rated power output of 3 watts or less and an antenna array designed to produce an elliptical pattern with dimensions, at 1,000 feet above the antenna, of approximately 2,400 feet in width and 4,200 feet in length. Airborne marker beacon receivers with a selective sensitivity feature should always be operated in the "low" sensitivity position for proper reception of ILS marker beacons.
2.Ordinarily, there are two marker beacons associated with an ILS, the OM and MM. Locations with a Category II ILS also have an Inner Marker (IM). When an aircraft passes over a marker, the pilot will receive the indications shown in TBL 1-1-3.
(a)The OM normally indicates a position at which an aircraft at the appropriate altitude on the localizer course will intercept the ILS glide path.
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It looks to me that it's the FAA's desire for there to be some sort of range indication on an ILS approach, given to you by an OM. If the OM is not available, they tell you what is an appropriate substitute (Compass locator, PAR, ASR, NDB, or RNAV system). I'm thinking that if you don't have one of those approved substitutes, you may not be legal to shoot that approach.

Gucci, you may also want to check out AFM11-217v3 1.4.1...


 
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Sluggo63 said:
I'm thinking that if you don't have one of those approved substitutes, you may not be legal to shoot that approach.[/SIZE][/SIZE]

Gucci, you may also want to check out AFM11-217v3 1.4.1...
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Thats what I was looking for. So along with lateral and vertical guidance, range information is a required portion of the ILS approach.
 
Gucci Pilot said:
Thats what I was looking for. So along with lateral and vertical guidance, range information is a required portion of the ILS approach.
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That's how I read it, but I'm by no means the expert. Maybe a call down to AFFSA and see what they say. I'd be interested to hear what their official response is.
 
bobmrg said:
There is no FAF on an ILS approach. There is a final approach point, indicated by a lightning stroke and coincident with glide slope intercept. If your clearance includes something like "..tower at the marker," ask the controller to call the marker for you.

Bob Gardner
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http://tinyurl.com/qcybbh8
 
From FAA Order 6750.24E. Instrument Landing System and Ancillary Electronic Component Configuration and Performance Requirements

Marker Beacons. An Outer Marker (OM) or suitable substitute (refer to subparagraph 9c and Appendix A) is only required to indicate the final approach fix (FAF) for Nonprecision Approach (NPA) operations (i.e., localizer only). The FAF on CAT I/II/III ILS approach operations is the published glideslope intercept altitude, not the OM. Therefore, an OM or suitable substitute is not required for CAT I/II/III ILS approach operations. (my emphasis)​

Does that help?
 
midlifeflyer said:
From FAA Order 6750.24E. Instrument Landing System and Ancillary Electronic Component Configuration and Performance Requirements
Marker Beacons. An Outer Marker (OM) or suitable substitute (refer to subparagraph 9c and Appendix A) is only required to indicate the final approach fix (FAF) for Nonprecision Approach (NPA) operations (i.e., localizer only). The FAF on CAT I/II/III ILS approach operations is the published glideslope intercept altitude, not the OM. Therefore, an OM or suitable substitute is not required for CAT I/II/III ILS approach operations. (my emphasis)​
Does that help?
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Yea, it does. Thanks! I'm learnin' stuff all the time!
 
Sluggo63 said:
I was trying not to wade into this debate but...

And then there's this...

It looks to me that it's the FAA's desire for there to be some sort of range indication on an ILS approach, given to you by an OM. If the OM is not available, they tell you what is an appropriate substitute (Compass locator, PAR, ASR, NDB, or RNAV system). I'm thinking that if you don't have one of those approved substitutes, you may not be legal to shoot that approach.

Gucci, you may also want to check out AFM11-217v3 1.4.1...
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Your thinking is outdated. As noted above, the penalties for lack of OM/MM were deleted many years ago. As John Collins pointed out, GS intercept is the FAP for an ILS, with no OM required.
 
Well dang! Keep finding new stuff on this one!
 
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