ATL ILS 26R Question

[bike21]

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.

 

[derg]

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]

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.

 

[casey]

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

if you are established and cleared the approach with no other restrictions, then join the glideslope at whatever altitude you want between the last assigned and published intercept. All you need to do is crosscheck the altitude as you cross the intercept and make sure it matches up with the chart. You are all about semantics and being pedantic, but whether you descended on your own or via the GS, you end up at the same place.

The only real potential issues you need to be aware of is to make sure if you follow the glideslope outside the intercept that you do not 1)bust any altitudes published on the chart and 2) descend below the floor of class B airspace (assuming we are flying transport cat aircraft into major airports).

if memory serves me, you've had issues with this concept before

 

[meritflyer]

Actually Casey, no. That post was about what ATC does as for intercept altitudes.

I still dont personally like grabbing the GS anywhere other than as published. Any and all guess work is eliminated this way. Tell that to your new IR guy - hey buddy, pick up the GS wherever the hell you want. You'll be fine.

I'll stick to using step downs.

 

[mikecweb]

Actually Casey, no. That post was about what ATC does as for intercept altitudes.

I still dont personally like grabbing the GS anywhere other than as published. Any and all guess work is eliminated this way. Tell that to your new IR guy - hey buddy, pick up the GS wherever the hell you want. You'll be fine.

I'll stick to using step downs.

Level off 4 times with a multi-engine complex airplane vs. no level offs....I fly freight and I know which one is more comfortable for passengers/less work load.

 

[E_Dawg]

I still dont personally like grabbing the GS anywhere other than as published. Any and all guess work is eliminated this way. Tell that to your new IR guy - hey buddy, pick up the GS wherever the hell you want. You'll be fine.

I'll stick to using step downs.

...why?? This is where you can use what you know and put it to work for the comfort of the passengers and for the benefit of your workload. And it's just plain safer to follow a needle down than it is to keep chopping and dropping to a new altitude every few miles.

 

[zmiller4]

...why?? This is where you can use what you know and put it to work for the comfort of the passengers and for the benefit of your workload. And it's just plain safer to follow a needle down than it is to keep chopping and dropping to a new altitude every few miles.

Absolutely agree. There's a reason that precision approaches are vastly preferable to nonprecision--they get you established in a stabilized descent (at a slower descent rate) much more readily than a non-precision approach.

The *only* reason I see for using stepdowns is if you're flying a big old jet and a smaller aircraft is getting vectored in to follow you at the published GSIA, it would be considerate to use the stepdown altitudes so they can at least try to avoid your wake on the FAF. We deal with this all the time coming in on the downwind for 24R at LAX when there are a bunch of arrivals from the Civet or Seavu tracking the glideslope down--it's not a big deal VFR (most of the time), but in IMC it sucks to be following a heavy with no real way to avoid going through the wake.

 

[surreal1221]

Merit, as a one time ATC student. . .your philosophy will get looked down upon by a number of controllers. . . AND pilots. But hey, you're PIC. Do as you wish. It's just silly, from a controllers point of view. Especially if I were to clear you for the approach @ 6k, and I start to see you step down, level out. . . step down, level out. . . step down, level out. . .just keep it steady so I (if I were a controller) know what the hell you are doing, lol.

Only love for you though.

 

[derg]

Actually Casey, no. That post was about what ATC does as for intercept altitudes.

I still dont personally like grabbing the GS anywhere other than as published. Any and all guess work is eliminated this way. Tell that to your new IR guy - hey buddy, pick up the GS wherever the hell you want. You'll be fine.

I'll stick to using step downs.

In the real world, you're rarely going to get cleared for the approach when you're already at the glideslope intercept altitude.

Some airports will leave you high, others will dive 'n drive you low, some controllers lose SA and mess the whole thing up, be flexible.

Go into ONT on an IFR flight plan, descending from the flight levels and tell me all about demanding to only intercept the glideslope at GSIA.

Be flexible, learn to improvise.

 

[casey]

Actually Casey, no. That post was about what ATC does as for intercept altitudes.

I still dont personally like grabbing the GS anywhere other than as published. Any and all guess work is eliminated this way. Tell that to your new IR guy - hey buddy, pick up the GS wherever the hell you want. You'll be fine.

I'll stick to using step downs.

riddle me this.

hypothetical ILS, published intercept altitude is 2000ft. You are on a vector at 4000ft, and cleared '4000 until established, cleared the approach'. Consider a few different pilots.

1) as soon as loc is alive, he throws out the brakes, props full, and descends to 2000 ft

2) after loc is captured, he starts a 1500 fpm descent to 2000 ft

3) after loc is captured and glideslope is alive, he starts a descent that keeps him one dot below gs to 2000 ft

4) after loc is captured, he follows the glideslope down.

now while these are all different techniques they all have something in common, when you cross the marker you are at 2000 ft, on the glide. Where is the "guesswork"? Do you somehow think that if i intercept the glidepath from 4000 ft that when i am passing through 2000 ft i will not be over the proper fix for the intercept? I honestly dont understand.

When i had instrument students i taught them both ways, following the glide and stepping down as allowed. I informed them of the potential issues with the glide (mandatory altitudes, min/max altitudes, the effects of density altitude on the stepdown altitudes vs the glidepath, etc). I gave them multiple tools to use and i surely didnt give the method that wasnt my personal preference a negative stigma when it came up.

 

[CaptBill]

Ajaay, Balli, Freal and Smltz are all depicted as "do not descend below altitudes." There are no hard altitude requirements for this approach. It is perfectly acceptable to intercept the GS at 6000' and I would strongly recommend it as it is more comfortable for the passengers and you do not run the risk of descending below a "at or above" altitude as you are working to step down repeated times. Once you intercept the glideslope you can then set your missed approach altitude (in the case of a Boeing) and be done with it. Why increase your workload in such a critical phase of flight? The asterik allows ATC to descend you to 5000 or 3800 to intercept the glideslope without taking the altitude restrictions for the preceeding fix(s) into account. If ATC says "descend and maintain 3800' and cleared for the approach," you do not need to be concerned with the 6000 over Smltz or the 5000' over Freal. They have simply told you to intercept the glideslope closer to the runway and at a lower altitude than usual. Perhaps they needed you at 3800 feet for traffic or some other operational reason. If you are way out and are descended to 3800' by ATC, you may want to insure that you will remain in Class B airspace as to the east of Atlanta outside 20 nm the Class B floor is at 4000 or 5000' depending on where you are. Houston used to have a habit of getting you to 2000' a little early arriving from the east, and I occasionally see it happen at other airports as well. No big problem, but awareness and coordination with the approach controllers is a must.

 

[ClearedToThe]

If you read the * note again on the NACO plate, it says "When assigned by ATC, intercept glidepath at BALLI, 3800; or FREAL, 5000". Clearly, this statement indicates that the GS can be intercepted and followed down at altitudes other than the GSIA of 2700 @ AJAAY...

Also, I have not been able to find any statement in the AIM stating that you can't intercept GS at any altitude other than the lighting bolt... Personally I feel simply cross checking altitudes on the GS is alot less workload than doing step downs to GSIA.

PS - anyone else notice that SMLTZ is an IAF

 

[DE727UPS]

Another reason it's safer to just follow the GS down is you have vertical guidance. If you do the stepdowns, you better not bust an altitude or you could get a CFIT.

 

[derg]

Less work too.

In my last airplane, whenever you start 'diving and driving' you're just begging for "Murphy" to catch you tweaking your pitch mode while you're in altitude capture and the altitude arm disengaging.

"Southernjets 101, say altitude?"

"altitude... yuk yuk yuuu...aroo?! GREAT SCOTT!"

 

[hkrach]

PS - anyone else notice that SMLTZ is an IAF

I wonder if the ILS 26L has an IAF of GLAVN or MADUX