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ILS Question

ABXbooger

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I have a question for someone who is currently taching IFR practicals...

When cleared for an ILS approach with multiple stepdowns, can you capture the glideslope if the glideslope makes you go below the published altitudes at each intersection?

Shot the ILS 25L into LAX tonight and it has 3 or 4 intersections depicted with altitudes. We were cleared for the approach 25 miles out, captain complied with these altitudes even though it put us above the glideslope, we then had to intercept from above.

Just continuing my education...thanks.
 

NYCPilot

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I've always understood that you should never intercept the GS from above as you may be following false indications. Usually an abnormally high rate of descent with an inability to capture the GS needle.

Looking at the LAX 25L plate, it seems that adhering to charted minimum altitudes (albeit above the GS) up until just past HUNDA INT. should be correct. Approaching HUNDA you should be no lower than 3500’ with a further descent beyond HUNDA to 3200’, which is the minimum GS intercept altitude.

Maintaining these minimum step-down altitudes (between FUELR 26.4 DME and HUNDA 12.4) up until HUNDA should cause the GS needle to eventually be above you, then moving downward for an intercept from below. Past HUNDA descending to 3200’ should allow you to intercept and capture the GS down to the runway.

The stepdown fixes prior to LIMMA INT. will need to be complied with as they are applicable to both an ILS and LOC approach. LIMMA and LADLE have a 1900’ and 620’ minimum altitude restriction only for LOC approaches as indicated by the asterisk. These altitudes will be disregarded inside the FAF on a precision approach.
 

check6

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The step downs would be for the LOC only approach. The ILS you would just intercept and follow down. If I'm understanding your question correctly.
 

TR4A

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Following the stepdown altitudes will keep you from dropping below the Class B airspace. On other approaches it might be there for obstacles.
 

Singlecoil

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I agree with NYC in that you have to comply with the restrictions outside HUNDA. The published GSIA is 3200, anything above that with a restriction must be complied with.

I don't agree that you have to intercept from below. When shooting this approach, you are very close to the GS when crossing HUNDA at 3500 and it is obvious that you are receiving the correct GS. You simply arm the ILS passing HUNDA, increase the VS to about a 1500 fpm descent and join the GS.
 

NYCPilot

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Singlecoil said:
I agree with NYC in that you have to comply with the restrictions outside HUNDA. The published GSIA is 3200, anything above that with a restriction must be complied with.

I don't agree that you have to intercept from below. When shooting this approach, you are very close to the GS when crossing HUNDA at 3500 and it is obvious that you are receiving the correct GS. You simply arm the ILS passing HUNDA, increase the VS to about a 1500 fpm descent and join the GS.
Yes, I agree, but I was merely stating (or implying) that you can ride the GS if you pick it up while at or above the minimum step-down altitude. It does seem like while at 3500' you may be very close to picking it up anyway.

I guess the original question was whether you could ride the GS from further out (25 NM) if it meant having to go below the step-down fix. That's a no-no. But if you pick it up at 3500' or just prior to that, by all means ride it down, just don’t go below the minimum altitudes. This may not be possible if you intercept it too early and too far out, as the GS will inevitably go below the step-down fix.

Also, by flying level at 3500' until HUNDA, you make your job a little easier. By intercepting at a lower altitude closer in, rather than further out, you do less flying on the glideslope. This will reduce the amount of concentration and length of time that one might need in order to hold the needles.
 

ABXbooger

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Thanks for the replies, it is unbelievably rare on this board to have intelligent conversation.

It is truly amazing how much info we have to know, some of it gets lost in the shuffle.

My dad always said if you aren't learning you are dangerous...

Booger
 

SiuDude

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ABXbooger said:
Thanks for the replies, it is unbelievably rare on this board to have intelligent conversation.

It is truly amazing how much info we have to know, some of it gets lost in the shuffle.

My dad always said if you aren't learning you are dangerous...

Booger
In my best Van Kilmer voice:
"You're Dangerous!"


sorry
 

hmmurdock

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ABXbooger said:
I have a question for someone who is currently taching IFR practicals...

When cleared for an ILS approach with multiple stepdowns, can you capture the glideslope if the glideslope makes you go below the published altitudes at each intersection?

Shot the ILS 25L into LAX tonight and it has 3 or 4 intersections depicted with altitudes. We were cleared for the approach 25 miles out, captain complied with these altitudes even though it put us above the glideslope, we then had to intercept from above.

Just continuing my education...thanks.
Greetings..

I Have flown into LA fairly recently. If memory serves, They will clear you for the approach which also has the step downs on the arrival. You comply with all the crossing restrictions, then intercept the glideslope just outside the fix I believe. Hope this helps.

Take care
 

banned username 1

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Yes, you are all correct. You must adhere to the crossing restrictions and as so named, means that your altitude is restricted at that crossing fix. Tempting as it is to follow the G/S, if it takes you below the altitude over the fix, you shouldn't follow it. We do, but we'll fudge a little and shallow out the rate of descent and go high if necessary until at the true g/s intercept point and then it's follow the needles down to DH.

Yes, it is refreshing to see posts that are informative and not caustic.

Happy Landings,

UAL78
 
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