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OLV GPS 36 approach question



 
 
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  #21  
Old August 9th 06, 09:23 PM posted to rec.aviation.ifr
Sam Spade
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Posts: 1,326
Default OLV GPS 36 approach question

wrote:
Not so with this past February's AIM and ATC procedure change:

You informed me of this change a month or two ago, but that doesn't
change the fact that published altitudes apply after arriving at the
IF. An assigned altitutde below an intermediate segment altitude would
be an error, as I think you'd agree.


I would agree, and if there were a step-down altitude in the
intermediate higher than 2,100, then the assignment would have been in
error.

But, in the circstances with this IAP, it was functionally no different
than "vectors to final" (i.e., the intermediate segment), which wouldn't
be any surprise to have done at 2,100 feet.

Having said that, because of the nuance of this new procedure, an
assignment to cross DOCAP at 2,800 would be better human-factors.

However, as I reviewed the original post, he said he was cleared to
DOCAP. In my mind, I pictured the right base entry, which is the one
that I usually make, but DOCAP is the IF/IAF and which makes it a
straight-in. The first published altitude IS (I think) 2,100, so the
controller didn't make an error after all. The 2,800 that the OP
mentioned was probably the straight in sector altitude, which becomes
irrelevant when cleared to the IF.

  #23  
Old August 10th 06, 01:56 AM posted to rec.aviation.ifr
Sam Spade
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Posts: 1,326
Default OLV GPS 36 approach question

A Lieberma wrote:


Bear with me as I am really trying to understand this....

Looking at the FAA version of the approach plate, profile section, it has
2800 to DOCAP, then descend to 2100 at CICAL for the final approach into
OLV.

Based on what you are saying, since I am pretty much a straight in approach
that it's allowable to be cleared by ATC below the profile altitude of 2800
10 miles BEFORE DOCAPS?

10 miles outside DOCAPS, my instructions were descend and maintain 2100,
cleared for the GPS 36.

Allen


Think in terms of being vectored to the final approach course on an ILS.
When done correctly, the controller will vector you at an altitude
below the G/S.

If this approach were an ILS and the controller was setting you up to
intercept the "final" perhaps 3 miles prior to CICAL on a 30 degree
intercept angle. The controller would almost certainly descend you to
2,100 to intercept. He might have you at 2,100 10 miles prior to intercept.

Do you see any difference with your handling, albeit with a new ATC/AIM
procedure?
  #24  
Old August 10th 06, 04:08 AM posted to rec.aviation.ifr
[email protected]
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Posts: 10
Default OLV GPS 36 approach question

Looking at the FAA version of the approach plate, profile section, it
has
2800 to DOCAP, then descend to 2100 at CICAL for the final approach
into
OLV.

The 2,800 ft segment you see is the Hold-in-Lieu. A HIL is part of the
initial segment, which doesn't begin until the IAF. From your
direction of flight, the HIL wasn't required for you, so its altitude
didn't apply.

Regardless, ATC has a right to assign you an altitude to maintain until
you arrive at a certain fix; only AFTER you arrive there do published
altitudes apply. Until then, you're relying on their MVA to keep you
safe.

If they had cleared you to ECILE, and told you to maintain 2,100, then
there would have been a problem. You're fine until you get to ECILE,
but the moment you pass that fix, you're in violation of 91.177.

Same thing if you had come from the north direction to DOCAP. You'd be
fine at 2,100 until the fix, but the HIL is required from this
direction and you'd be in violation of 91.177 once you started the hold
entry.


Sam: The fix DOCAP is labeld IF/IAF. Does the segment from DOCAP to
CICAL use initial or intermediate ROC ?

  #25  
Old August 10th 06, 02:42 PM posted to rec.aviation.ifr
John Clonts
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Posts: 33
Default OLV GPS 36 approach question


wrote:
Looking at the FAA version of the approach plate, profile section, it
has
2800 to DOCAP, then descend to 2100 at CICAL for the final approach
into
OLV.

The 2,800 ft segment you see is the Hold-in-Lieu. A HIL is part of the
initial segment, which doesn't begin until the IAF. From your
direction of flight, the HIL wasn't required for you, so its altitude
didn't apply.

Regardless, ATC has a right to assign you an altitude to maintain until
you arrive at a certain fix; only AFTER you arrive there do published
altitudes apply. Until then, you're relying on their MVA to keep you
safe.

If they had cleared you to ECILE, and told you to maintain 2,100, then
there would have been a problem. You're fine until you get to ECILE,
but the moment you pass that fix, you're in violation of 91.177.

Same thing if you had come from the north direction to DOCAP. You'd be
fine at 2,100 until the fix, but the HIL is required from this
direction and you'd be in violation of 91.177 once you started the hold
entry.


It seems to me you are ignoring the depiction of the southern sector on
the map view that shows 2800. This applies to aircraft inbound to
DOCAP from anywhere southern. Why are you saying that it does not
apply? (I.e. why is the controller allowed to clear the a/c to DOCAP
and descend to 2100?).
--
Thanks,
John Clonts
Temple, Texas

  #26  
Old August 10th 06, 03:19 PM posted to rec.aviation.ifr
Sam Spade
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Posts: 1,326
Default OLV GPS 36 approach question

wrote:
Looking at the FAA version of the approach plate, profile section, it
has
2800 to DOCAP, then descend to 2100 at CICAL for the final approach
into
OLV.

The 2,800 ft segment you see is the Hold-in-Lieu. A HIL is part of the
initial segment, which doesn't begin until the IAF. From your
direction of flight, the HIL wasn't required for you, so its altitude
didn't apply.

Regardless, ATC has a right to assign you an altitude to maintain until
you arrive at a certain fix; only AFTER you arrive there do published
altitudes apply. Until then, you're relying on their MVA to keep you
safe.


ATC has an obligation to assign an offroute altitude. If they don't
then the pilot has a regulatory obligation to challenge the lack of an
altitude assignment (one of the many changes provided by TWA 514
crashing into Mt. Weather on Dec 1, 1974.)

In this instance it would have been reasonable for the pilot to
challenge the 2,100-foot assignment since 2,800 is shown at DOCAP.

When this change to the AIM and ATC Order was discussed, I think
everyone envisioned 2,800 being assigned for a direct-to DOCAP. But,
once the real-world takes over...

The controllers really have to know the IAP to assign any altitude less
than that shown in the profile at the IF. I am not sure that is the
conservative way to go, but it is certainly legal so long as there isn't
a step-down in the intermediate somewhere that is missed.


If they had cleared you to ECILE, and told you to maintain 2,100, then
there would have been a problem. You're fine until you get to ECILE,
but the moment you pass that fix, you're in violation of 91.177.

Same thing if you had come from the north direction to DOCAP. You'd be
fine at 2,100 until the fix, but the HIL is required from this
direction and you'd be in violation of 91.177 once you started the hold
entry.


Sam: The fix DOCAP is labeld IF/IAF. Does the segment from DOCAP to
CICAL use initial or intermediate ROC ?

That is the intermediate segment with 500-foot ROC requirements. But,
at a location like this, airspace and descent gradient requirements are
limiting, not ROC. There is probably at least 1,200 feet or more, of
ROC in this particular intermediate segment. The MVA overlying this
intermediate segment is 2,000 feet.
  #29  
Old August 10th 06, 04:19 PM posted to rec.aviation.ifr
[email protected]
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Posts: 10
Default OLV GPS 36 approach question

It seems to me you are ignoring the depiction of the southern sector
on
the map view that shows 2800. This applies to aircraft inbound to
DOCAP from anywhere southern.

That sector is essentially a feeder route. If cleared for the approach
within that area, you could descend down to 2,800 if you were above it,
absent any other altitude assignment by ATC.

Many approaches have feeder routes, but you're not obligated to fly
them to the IAF if ATC clears you direct to the IAF and assigns an
altitude.

  #30  
Old August 10th 06, 04:31 PM posted to rec.aviation.ifr
[email protected]
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Posts: 10
Default OLV GPS 36 approach question

If they don't then the pilot has a regulatory obligation to challenge
the lack of an
altitude assignment

Unless they've changed 91.175, it merely says that if an altitude isn't
assigned when an approach clearance is received, the pilot is to
maintain the last altitude assigned. Where is the regulatory
requirement to challenge the lack of assignment?

When this change to the AIM and ATC Order was discussed, I think
everyone envisioned 2,800 being assigned for a direct-to DOCAP. But,
once the real-world takes over...

I'm not clear on how this clearance relates to the new change to ATC
procedures. That pertains to direct to IF's, but this fix is a
combined IAF/IF and has been for years, most likely prior to the AIM
change, and a clearance direct to an IAF has long (forever?) been ok.

 




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