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ILS vs. ILS or LOC approaches....???

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ILS vs. ILS or LOC approaches....???

Old 02-02-2007, 03:37 AM
  #11  
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Originally Posted by schoolio View Post
Think back to your approach clearance..."Cleared ILS Rwy 17". You weren't cleared for the LOC.

I don't know the contingencies available to ATC. If you report the failure, can they immediately clear you to continue via the "ILS Rwy 17 LOC only"? Or are they required to have you execute the missed? This I don't know. I tend to think that they will send you around if you're IMC.

In the case of an inoperative GS before you commence the approach - I have been cleared for an "ILS Rwy 17 LOC only" approach before, Part 121.

EDIT: Oh yeah, since this is in the pre-interview forum, I just thought I ought to mention that if you are in a sim ride at an airline interview, and this happens, and you continue using the LOC only, don't plan on working there.

Executing an immediate missed approach is completely counter to what the FAA wants you to do. The MAP corrider obstacle clearance starts at the MAP and not before. The approach is TERPSd assuming you will always drive to the MAP before starting the MAP. Period. If you have to execute a MAP early you need to be talking to the controller, because you are NOT guaranteed obstacle clearance.

The TERPS manual is quite clear that an "ILS" is a combined procedure and the "LOC" procedure is a legal procedure if minimums are included on the plate.

I have heard controllers clear pilots for "ILS 17 localizer procedures" as well. But that doesn't make it correct. The ATC manual is clear as well in that they are supposed to clear pilots to fly procedures by the title of the procedure only. Now if the glideslope is OTS then the controller may be doing you a favor by reminding you that you have to fly the localizer procedures. But by the book, even if the gs is OTS he doesn't have to say anything but "Cleared ILS 17" Which I've seen. Although I do belive they are supposed to remind you of the outage.

I highly doubt that last note. In a military sim if you don't hack the clock at the FAF then you can guarantee that the gs will fail. Then you are expected to transition to LOC if you still can ident the MAP and you are above MDA when it happens.

Since hopefully I'll be in the airline sim in a couple of months I would like to know if there are any airline check airman out there that can shed some light on schoolio's last note.
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Old 02-02-2007, 03:44 AM
  #12  
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Originally Posted by palgia841 View Post
I forgot to mention this: If a company's SOPs specifically say that you should execute an immediate missed approach if the GS fails, then you should abviously follow the SOPs and do it. But that has nothing to do with the fact that it is perfectly legal to continue with a LOC approach.
If there are any companies out there with procedures like this I'd like to know what their procedure is for making sure that you don't turn early on the MAP.

Even in this case you better be able to ident the MAP, by DME or timing as backup. Back to the TERPS thing, especially on a precision, if you go missed early you better be driving straight ahead to the MAP before making any turns, otherwise you,ve left protected airspace.
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Old 02-02-2007, 07:28 AM
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As for the first question, sorry, I was half asleep when I responded and didn't see the note you put in there "if you've adequately briefed the LOC approach". That is correct. If you've briefed it, it's no problem. The problem is that nobody briefs it. Palgia, if you brief the LOC every time you do an ILS, kudos to you. I don't know if you fly 121, but I can tell you that it isn't done here nor at any other airline I've heard about.

Also, if you've descended through the LOC MDA but not below DH when the GS fails, what are you going to do? Climb back to MDA? Execute missed? Now you've got a dilemma, and if you haven't briefed that specific situation, well, now what?

Originally Posted by Texandrvr
Executing an immediate missed approach is completely counter to what the FAA wants you to do. The MAP corrider obstacle clearance starts at the MAP and not before. The approach is TERPSd assuming you will always drive to the MAP before starting the MAP. Period. If you have to execute a MAP early you need to be talking to the controller, because you are NOT guaranteed obstacle clearance.
I beg to differ on the first sentence. You can execute the missed approach. You are correct in stating that obstacle clearance is only guaranteed beginning at the MAP. You must continue toward the missed approach point before starting any turns. Can you execute the climb portion of the missed approach without turning? Of course you can. Like you mentioned here:

Originally Posted by Texandrvr
Even in this case you better be able to ident the MAP, by DME or timing as backup. Back to the TERPS thing, especially on a precision, if you go missed early you better be driving straight ahead to the MAP before making any turns, otherwise you,ve left protected airspace.
From FAA Order 7110.65:

Chapter 4-8-1
Examples of clearances that may be issued include:
EXAMPLE-
"Cleared Approach."
"Cleared V-O-R Approach."
"Cleared V-O-R Runway Three Six Approach."
"Cleared F-M-S Approach."
"Cleared F-M-S Runway Three Six Approach."
"Cleared I-L-S Approach."
"Cleared Localizer Back Course Runway One Three Approach."
"Cleared R-NAV Runway Two Two Approach."
"Cleared GPS Runway Two Approach."
"Cleared BRANCH ONE R-NAV Arrival and R-NAV Runway One Three Approach."
"Cleared I-L-S Runway Three Six Approach, glideslope unusable."
"Cleared M-L-S Approach."
"Cleared M-L-S Runway Three Six Approach."
"Cleared M-L-S Runway Three Six Approach, glidepath unusable."
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Old 02-02-2007, 08:13 AM
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My personal philosophy is to not convert an ILS into a LOC if it was not briefed as a LOC, especially near or inside the marker...too many opportunites to goon up the MDA if you try to do it on the fly. I don't even remember what my company procedure is on this, but I doubt they allow it.
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Old 02-02-2007, 08:41 AM
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Originally Posted by schoolio View Post
As for the first question, sorry, I was half asleep when I responded and didn't see the note you put in there "if you've adequately briefed the LOC approach". That is correct. If you've briefed it, it's no problem. The problem is that nobody briefs it. Palgia, if you brief the LOC every time you do an ILS, kudos to you. I don't know if you fly 121, but I can tell you that it isn't done here nor at any other airline I've heard about.

Also, if you've descended through the LOC MDA but not below DH when the GS fails, what are you going to do? Climb back to MDA? Execute missed? Now you've got a dilemma, and if you haven't briefed that specific situation, well, now what?



I beg to differ on the first sentence. You can execute the missed approach. You are correct in stating that obstacle clearance is only guaranteed beginning at the MAP. You must continue toward the missed approach point before starting any turns. Can you execute the climb portion of the missed approach without turning? Of course you can. Like you mentioned here:



From FAA Order 7110.65:

Chapter 4-8-1
Examples of clearances that may be issued include:
EXAMPLE-
"Cleared Approach."
"Cleared V-O-R Approach."
"Cleared V-O-R Runway Three Six Approach."
"Cleared F-M-S Approach."
"Cleared F-M-S Runway Three Six Approach."
"Cleared I-L-S Approach."
"Cleared Localizer Back Course Runway One Three Approach."
"Cleared R-NAV Runway Two Two Approach."
"Cleared GPS Runway Two Approach."
"Cleared BRANCH ONE R-NAV Arrival and R-NAV Runway One Three Approach."
"Cleared I-L-S Runway Three Six Approach, glideslope unusable."
"Cleared M-L-S Approach."
"Cleared M-L-S Runway Three Six Approach."
"Cleared M-L-S Runway Three Six Approach, glidepath unusable."
You're correct. I should have worded that differently. Executing a MAP is not a problem. I was thinking solely about the turn portion. You are always supposed to drive to the MAP before executing the turn portion of a MAP, for the reasons I stated. But the climb of course is no problem. However if you are in the habit of not briefing the LOC, then are you hacking the clock at the FAF? Or checking the gs crossing alt? If you're not hacking the clock and timing is your only method of identifying the LOC MAP, then what do you do when the gs fails? Granted that's a worst case scenario that hopefully never happens. But that's what we're supposed to be prepared for, right?

Thanks for the reference of the controller terminology. I have heard that before but wasn't sure if the "...glideslope unusable" was required or technique. But notice the "ILS 17 Localizer procedures" is not one of the examples given.

And I agree that you should not climb back up to the MDA if you lose the gs below MDA.
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Old 02-02-2007, 08:41 AM
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Sorry, didn't mean to post twice.
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Old 02-02-2007, 09:56 AM
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http://www.airlinepilotforums.com/sh...hlight=ILS+LOC

Here this has been argued already here!
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Old 02-02-2007, 10:57 AM
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Originally Posted by Texandrvr View Post
If there are any companies out there with procedures like this I'd like to know what their procedure is for making sure that you don't turn early on the MAP.

That's a good question. I suspect 99.9% of the times you'll be in radar contact, so you just advise ATC and they'll vector you back around while ensuring your obstacle clearance (if the terrain allows it, they will make you start the Missed approach procedure prior to the MAP).

Now, if you're in a different country, at an airport that has an ILS, but no radar, or if there is a radar outage, then you need to have some alternative means of identifying the MAP. Timing works fine, but what if you forgot to start it?
I think with today's avionics, a crew executing an ILS will have an FMS overlay of the approach anyways, as well as the runway depicted on the nagivation display. So basically you'd fly the LOC until runway threshold (or slightly before it) and start your MAP. In some FMSs, you'll have an FMS waypoint overlayed on the ILS MAP.
Even in a little C172, if you have GPS, you can use it to derive the distance from both the OM/FAF and the LOC antenna. By then looking at the bottom of the approach chart (profile view) you can kinda determine the location of the ILS MAP, at least within a 0.5nm accuracy.

What if you have no GPS/IRS RNAV or don't have any database information for the region AND you don't have radar AND you forgot to start the time? I'm not sure. I would probably climb to the MSA while tracking the localizer and execute the missed as soon as I saw my LOC sensitivity become impossible to track. That should tell me I am either directly over or very close to the LOC antenna (which is 1,000' past the end of my rwy). Although that means I'm probably passed the MAP, if I'm at the MSA I shouldn't hit any obstacles, right?

Any other comments on the above scenario?

What does the AF expect you to do when they fail your GS and you didn't start the time? (BTW, I used to give the exact same scenario to my students but I always gave them radar services)


PS. I know none of the above procedures are legal (ie. using an FMS/GPS overlay waipoint to identify the ILS MAP) but that's the only thing I can think of in the above scenario. Also, let's be honest, which do you think is more accurate, time or a GPS overlay waypoint ?
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Old 02-02-2007, 11:12 AM
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The AF says that if you are above the MDA, and you have DME then you can do LOC if you didnt start time, well shame on you... you get to go around.


If you are at the MSA in that short amount of distance, there either are no mountains or you got a wicked climbing airplane!
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Old 02-02-2007, 12:10 PM
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Originally Posted by palgia841 View Post


What does the AF expect you to do when they fail your GS and you didn't start the time? (BTW, I used to give the exact same scenario to my students but I always gave them radar services)
Exactly what you said. Call approach for a radar vector. Without radar your techniques sound good if you have that capability. But you're pretty much on your own at that point. The exercise is to try and drill into you that you should always brief the loc backup and hack the clock at the FAF if timing is available.
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