ATL ILS 26R Question

[EDUC8-or]

Here's the ILS 26R at ATL: http://204.108.4.16/d-tpp/0703/00026IL26R.PDF

Take a look at the little notes about intercepting the glidepath at BALLI or FREAL. I was flying with a CA who is wound up real tight and he freaks out about pretty minor details. We were given a vector and then told to maintain 6000 until established on the LOC, cleared ILS 26R. I was planning on following the GS the whole way down but he said we couldn't do it and had to gradually step down to 2700 to intercept at AJAAY.

The Jepp plates are a little different, they say "Only when assigned by ATC" instead of "When assigned by ATC." Any interpretations?

[meritflyer]

You're captain was 100% correct, IMO. Thats exactly how I would've done it as well. The note says "when assigned by ATC". Nowhere in your clearance were you assigned to intercept GS at any fix other that the FAP which is this case is AJJAY. The plate clearly says "only when assigned by ATC". If you werent assigned it, why would you just do it?

I personally think that both the Jepp wording and the NACO wording mean exactly the same thing.

[EDUC8-or]

I've done the visual to the same runway and you cross those fixes at the depicted altitudes if you follow the GS, including AJAAY. Also, there is no note about intercepting the GS at SMLTZ.

[Stone Cold]

Show me where there's a max altitude at any of those fixes. You can step down as quickly or slowly as you want, as long as you aren't any lower than those specific altitudes at those fixes (i.e., freal @ 5000'). The when assigned by ATC, in my interpretation, is so ATC can give you a lower altitude. I would side with the initial poster and say you could do stepdowns or follow the glidepath, either way is correct.

Now, if they'd said to descend as published, and intercept the GS at ajaay at 2700', then it would be a different game. As stated, you could have followed the GS down from intercept.

[BobDDuck]

Care to share some initials?

I have always just joined the ILS at 6000 (or 7000 I think if you are on 26L) and trucked on down. The glideslope should bring you through those fixes on altitude.

Merit, in what publication does it say that you have to intercept the glideslope at the final approach fix?

[tgrayson]

Originally Posted by EDUC8-or

I was planning on following the GS the whole way down but he said we couldn't do it and had to gradually step down to 2700 to intercept at AJAAY.

I agree with you. The GS is a tool you can use to meet the crossing restrictions. The only difference between following the GS and "chopping and dropping" is the rate of descent.

I don't read a meaningful distinction between "Only when assigned by ATC" and "When assigned by ATC." What those notes appear to do is make the GS primary prior to the published FAF, implicitly waiving the crossing restrictions.

[E_Dawg]

You're cleared for the approach. You can follow the min alts on the chart and descend at your discretion to get there. There's no max alt on the chart and it's probably a better ride to just go down at a constant vertical speed, so long as the GS is cross checked against the min alts for each DME fix on the chart. That said if the captain wants to fly it like a non precision prior to AJAAY I would just do that.

I would guess the intent of that note is to allow the FAF to be farther out in incliment weather so you can continue the approach.

[Doug Taylor]

Hit the glideslope at 6000, follow it down.

I've flown that approach for almost a decade with hundreds of different crews and I haven't seen anyone do the stepdowns until intercepting the glideslope.

Besides, if you go NORDO and you're on a vector, do you think ATL wants the NONCOMM stuff? Nope, get in line, land the jet!

[meritflyer]

Originally Posted by BobDDuck

Merit, in what publication does it say that you have to intercept the glideslope at the final approach fix?

Well, there is no FAF technically on an ILS.

I just wouldnt teach or get into the habit of intercepting the GS from any point on the LOC. I would comply with the min altitudes suggested on the plate. I never quoted a publication. I simply said it was my opinion. The typical GS is only 10 NM long.

If I was the CA, I would've done it the same way. I am the PIC and get to make those decisions.

[Stone Cold]

Originally Posted by meritflyer

Well, there is no FAF technically on an ILS.

I just wouldnt teach or get into the habit of intercepting the GS from any point on the LOC. I would comply with the min altitudes suggested on the plate. I never quoted a publication. I simply said it was my opinion. The typical GS is only 10 NM long.

If I was the CA, I would've done it the same way. I am the PIC and get to make those decisions.

Yes, there is a FAF on an ILS. Where do you start your time, or do your gear down, flaps full, before landing checklist (or whatever is applicable to your airplane)? At the FAF...on glideslope and LOC, at GS intercept altitude (or as published).

This is where what's done in a training environment and what's done in a real world environment are different and it pays to have some real world experience instead of only in the training bubble.

[meritflyer]

Originally Posted by Stone Cold

Yes, there is a FAF on an ILS. Where do you start your time, or do your gear down, flaps full, before landing checklist (or whatever is applicable to your airplane)? At the FAF...on glideslope and LOC, at GS intercept altitude (or as published).

Its actually called a final approach point.

[tgrayson]

Originally Posted by BobDDuck

I have always just joined the ILS at 6000 (or 7000 I think if you are on 26L) and trucked on down. The glideslope should bring you through those fixes on altitude.

That isn't true at all locations. I've been told there have been some violations issued to crews using the GS as primary means of vertical navigation prior to the FAF. In those cases the GS did not meet the crossing restrictions along the course.

[Stone Cold]

Originally Posted by meritflyer

Its actually called a final approach point.

Not quite true, but you made me look up the minutia BS I hate!!

Final Approach Point: When an FAF is not designated, such as on an approach which incorporates an on-airport VOR or NDB, this point is typically where the procedure turn intersects the final apporach course inbound. (Jeppesen Instrument/Commercial manual, p.7-5).

Final Approach Segment: for a precision approach begins where the glide slope is intercepted at minimum GS intercept altitude shown on the approach chart, or a lower altitude if authorized by ATC. (same page, same book).

[windowseat]

Originally Posted by Stone Cold

Not quite true, but you made me look up the minutia BS I hate!!

Final Approach Point: When an FAF is not designated, such as on an approach which incorporates an on-airport VOR or NDB, this point is typically where the procedure turn intersects the final apporach course inbound. (Jeppesen Instrument/Commercial manual, p.7-5).

Final Approach Segment: for a precision approach begins where the glide slope is intercepted at minimum GS intercept altitude shown on the approach chart, or a lower altitude if authorized by ATC. (same page, same book).

I think meritflyer was just being overly literal with FAF (since a fix implies it's in a permanent position). His argument was that it should be called FAP (since that point occurs wherever you intercept the GS, which is not always the same location i.e. a fix)

[bike21]

Originally Posted by tgrayson

That isn't true at all locations. I've been told there have been some violations issued to crews using the GS as primary means of vertical navigation prior to the FAF. In those cases the GS did not meet the crossing restrictions along the course.

I would like to see some examples. Every ILS I have ever done lines right up with the GS and crossing altitudes on the way down. If you are cleared for the approach at ### altitude, then you can either follow the GS down from that altitude or hit the step downs. The choice is yours. Of course, simply joining the GS at your current altitude is the easiest way to do it. (this assumes no actual restriction for max GS intercept)

[meritflyer]

Originally Posted by bike21

I would like to see some examples. Every ILS I have ever done lines right up with the GS and crossing altitudes on the way down. If you are cleared for the approach at ### altitude, then you can either follow the GS down from that altitude or hit the step downs. The choice is yours. Of course, simply joining the GS at your current altitude is the easiest way to do it. (this assumes no actual restriction for max GS intercept)

Are you suggesting that you can pick your own GSIA along the LOC?

[tgrayson]

Originally Posted by windowseat

I think meritflyer was just being overly literal with FAF (since a fix implies it's in a permanent position).

It IS a fixed position and Stone Cold stated it accurately. TERPS states it thusly:

1.2.24 Precision Final Approach Fix (PFAF). Applicable to all PA approach procedures. A 2D point located on the final approach course at a distance from LTP/FTP where the GPA intercepts the intermediate segment altitude (glidepath intercept altitude). The PFAF marks the outer end of the PA final segment.

[EDUC8-or]

Originally Posted by meritflyer

Are you suggesting that you can pick your own GSIA along the LOC?

In certain situations I would say yes, sometimes ATC will say, for example: Maintain 6000 until established on the LOC, cross AJAAY at 2700, clear for the ILS RWY 26R. As long as you stay at 6000 until established on the LOC and cross AJAAY at 2700 you could join the GS anywhere from 2700 to 6000.

I'm just using ATL as an example, but there are many places where instead of starting down immediately when they tell me to cross a fix at a certain altitude I'll just stay up and follow the GS down as long as I meet the restriction.

[bike21]

Originally Posted by meritflyer

Are you suggesting that you can pick your own GSIA along the LOC?

If you are cleared for the XYZ ILS approach at 4,000' for example, then yes if you are established on the LOC then you can intercept the GS and follow down.

There is no difference in descending early down to a lower published altitude, say 2,500' or staying @ 4,000' and grabbing the GS a few miles out. Either way you will cross the same fixes depicted in the profile view at the proper altitudes.

Dig?

[tgrayson]

Originally Posted by bike21

I would like to see some examples. Every ILS I have ever done lines right up with the GS and crossing altitudes on the way down. If you are cleared for the approach at ### altitude, then you can either follow the GS down from that altitude or hit the step downs. The choice is yours. Of course, simply joining the GS at your current altitude is the easiest way to do it. (this assumes no actual restriction for max GS intercept)

The example that usually comes up in this discussion is the Civet arrival into LAX, which aligns with the localizers.

[bike21]

Originally Posted by tgrayson

The example that usually comes up in this discussion is the Civet arrival into LAX, which aligns with the localizers.

Ah yes, I have done that one many times. CIVET is not depicted as a fix on the 25L approach, so I would not grab the glide slope there. Besides, you have many at or below / at or above altitudes to deal with here at LAX on the arrival and approaches.

I am thinking more of the common ILS scenario. Basic stuff.

[surreal1221]

I haven't read this whole thread. . . BUT. . .once you are cleared for the approach, assigned altitudes go out the window (once you are established on the LOC), and then you can continue down by stepping down. . . or holding the 6000 to intercept the GS. Both are fine, and legal

[BobDDuck]

I've never flown the Civet, but looking at it, as Bike said, it has nothing to do with the ILS, it just happens to be designed to dump you right on to the approach. I am 100% willing to believe that there are approaches where the GS does not provide protection for crossing restrictions, but I have never heard about them.

[Doug Taylor]

They're out there, but the most famous is CIVET. CIVET's VNAV descent is mutually exclusive to the ILS restrictions. Primarily why they say "after 'whatever' cleared ILS..."

I've never seen anyone 'step down' in ATL when cleared for the ILS. It's all in the brief:

"I'm going to join the glideslope at six..."

"Your airplane man, don't let me wake up and catch you reading".

[tgrayson]

Originally Posted by bike21

I am thinking more of the common ILS scenario. Basic stuff.

One that was quoted in the newsgroups was the Las Vegas 25L. It's not that easy to tell from the profile whether this happens or not. Using trig for a 3 degree slope shows that you might be 2 or 3 hundred feet low at Larre. However, the distances and altitudes on the profile are rounded, so there's a lot of slop in that figure. You'd have to fly it to know for sure.

Even for the CIVET arrival, the problem only happened on warmer than average day. On a standard day, the GS went right through the fixes, but on a warm day, the fixes rose, and the GS went lower.

I don't have an example that makes it very obvious; other pilots and TERPS guys have claimed they exist.