Answer on CEF ILS RWY 23 questions

The USAF terps guy Timothy Lovell sent John Haggerty (FAA terps guy) a
response to his query about the question I asked here, about the odd
step-down on the LOC vs LOC/DME versions of this approach. For those not
playing along at home, the LOC has a MDA of 900 feet, and the LOC/DME has
an MDA of 700 feet with a step-down fix 2.7 DME from the VORTAC.
http://204.108.4.16/d-tpp/0410/00447I23.PDF

The odd thing about the approach is that if you're doing the LOC/DME, then
before the step down, you can't descend to 900 feet like if you were doing
a straight LOC, but only to 1160'. I'll cut and paste his full answer
here, but the executive summary is that they put the step down to "provide
a constant descent rate on the procedure". Weird, eh? I don't see how
that stops you from doing a dive and drive to 1160, then another to 700
myself, but that's just me.

Oh, and the other question people had, about why the missed approach says
"tracking 228" instead of "fly heading 228" or "tracking ILS BC" - that's
just the way the USAF does things.

Ok, here's the response:
The LOC RWY 23 portion of the published KCEF ILS RWY 23 has a step
down fix to avoid terrain (544'MSL) with an adverse assumption of 100'
trees growing on it at N421439.00 W072827.00. This terrain gives you the
MDA for the S-LOC 23 of 544'(terrain)+100'(tree)+250'(Required Obstacle
Clearance)=894'=900'MDA. The published Step Down Fix (SDF) altitude of at
or above 1160' on the S-LOC/DME 23 is not only for terrain avoidance, but
to provide a constant descent rate on the procedure (FAF to SDF
379.81FPM/3.58 degrees, SDF to RWY 366.81 FPM/3.45 degrees). Were the SDF
altitude purely for terrain avoidance the SDF altitude would be 900'.
Having said all of that this procedure will change soon with the
implementation of new AF software and the corresponding criteria changes.
The SDF will move out to CEF 3DME and be raised to 1240', this altitude
raise will ensure that an aircraft executing a circling approach will not
descend below the highest circling MDA inadvertently.

To answer the last part of your question AF criteria requires
departure procedures and missed approach instructions to read track and
not heading. The logic behind this is that an instrument procedure is
built along a specific ground track to be flown and not a heading. The
procedure track does not take in to account wind drift, this
responsibility is placed upon the pilot. The AF trains its pilots very
specifically to fly tracks not headings on departure and or missed
approach.

I hope this answers yours and everyone else's questions.

Tim


Tim Lovell
Air Force Reserve Command, Terminal Instrument Procedures (TERPS) Manager


--
Paul Tomblin http://xcski.com/blogs/pt/
C isn't that hard: void (*(*f[])())() defines f as an array of
unspecified size, of pointers to functions that return pointers to
functions that return void.

On Thu, 14 Oct 2004 00:06:18 +0000 (UTC),
(Paul Tomblin) wrote:

the executive summary is that they put the step down to "provide
a constant descent rate on the procedure". Weird, eh?


Not only weird, but it does not answer our question. He has described
very well Why the approach was created this way, but in no way
communicates How a non-DME equipped aircraft can descend below 1160'
on a straight in LOC 23 approach. Even if it were possible to descend
at a 3.58 degree slope, nothing on the chart dictates Where or When
the final descent should take place to 900'.

Please don't misunderstand my response. I am grateful you took the
time to get this much information. It's just frustrating to be
subject to a typical "executive response" i.e, alot of information
without a real answer.

z
(Hangin' at 1160 wishin' he knew how to get down.)

On Thu, 14 Oct 2004 02:55:38 GMT, zatatime
wrote:

Not only weird, but it does not answer our question. He has described
very well Why the approach was created this way, but in no way
communicates How a non-DME equipped aircraft can descend below 1160'
on a straight in LOC 23 approach. Even if it were possible to descend
at a 3.58 degree slope, nothing on the chart dictates Where or When
the final descent should take place to 900'.

If without DME, you may descend to 900' after passing Belch.




--ron

Ron Rosenfeld wrote:

On Thu, 14 Oct 2004 02:55:38 GMT, zatatime
wrote:

Not only weird, but it does not answer our question. He has described
very well Why the approach was created this way, but in no way
communicates How a non-DME equipped aircraft can descend below 1160'
on a straight in LOC 23 approach. Even if it were possible to descend
at a 3.58 degree slope, nothing on the chart dictates Where or When
the final descent should take place to 900'.

If without DME, you may descend to 900' after passing Belch.

Without the special knowledge gained by the Air Force explanation, how could
you conclude that. The 2.5 DME stepdown states 1160. Descending to 900
after the FAF because I don't have DME would cause me to have a major pucker
factor and is contrary to every FAA-developed IAP.

If that is what the Air Force intends, then the chart should state, "Non DME
equipped aircraft using LOC minimums may descend to 900 after Belch.

Also, this business of Air Force pilots tracking is pure drivel; this
procedure is for civil use.

And, the hold-in-lieu pattern is screwed up. It should state "one minute" in
the profile view for non-DME aircraft. Further, since this is a RADAR
REQUIRED (not radar required or....) radar vectors are the entry method for
such an IAP. A hold-in-lieu would not be published on such an FAA
procedure. Finally, the missed approach going to a radar vector is contrary
to FAA policy.

The procedure is badly mangled and they just don't want to admit it. I
didn't look at the other IAPs, but the gurus at the FAA said they are screwed
up, too.

On Thu, 14 Oct 2004 01:06:31 -0700, wrote:


Without the special knowledge gained by the Air Force explanation, how could
you conclude that. The 2.5 DME stepdown states 1160. Descending to 900
after the FAF because I don't have DME would cause me to have a major pucker
factor and is contrary to every FAA-developed IAP.

The 2.5 DME fix does not (and cannot) apply if you don't have DME.

If that is what the Air Force intends, then the chart should state, "Non DME
equipped aircraft using LOC minimums may descend to 900 after Belch.

Talk to the chart makers. They are the one's who put the written procedure
into a graphic format.


Also, this business of Air Force pilots tracking is pure drivel; this
procedure is for civil use.

Most USAF procedures can be used by civilians. I don't have a problem with
course vs track, or some of the other differences. But then, I learned to
fly at KCEF when it was a SAC base.

I agree that the FAA would have described the procedure differently.

What do you think are the chances of either getting USAF to change their
procedures, or the FAA to review every USAF approach to ensure that it is
described the same as an FAA approach?

It might be easier to learn the differences.


--ron

Ron Rosenfeld wrote:



Most USAF procedures can be used by civilians. I don't have a problem with
course vs track, or some of the other differences. But then, I learned to
fly at KCEF when it was a SAC base.

Yes, but, it's usually at a military base with "prior permission only," which
places you squarely on notice to be diligent and not assume FAA standards, either
as to procedures or air traffic operations.


What do you think are the chances of either getting USAF to change their
procedures, or the FAA to review every USAF approach to ensure that it is
described the same as an FAA approach?

At this location the FAA might take over the procedures--eventually. As to the
latter: never.



It might be easier to learn the differences.

I don't think most of the issues with the procedure at issue are "differences,"
they are errors.



--ron

In a previous article, zatatime said:
On Thu, 14 Oct 2004 00:06:18 +0000 (UTC),
(Paul Tomblin) wrote:
the executive summary is that they put the step down to "provide
a constant descent rate on the procedure". Weird, eh?


Not only weird, but it does not answer our question. He has described
very well Why the approach was created this way, but in no way
communicates How a non-DME equipped aircraft can descend below 1160'
on a straight in LOC 23 approach. Even if it were possible to descend

John Haggerty raised that very question with him, and his response it that
because this is one of only three AFRC joint use airfields, they're going
to have to think about how to publish their procedures so that USAF and
civil pilots can both understand it. He says that in this case, they'll
be changing it to two plates - one called "ILS RWY 23" for the S-ILS,
S-LOC and CIRCLING, and one called "ILS or LOC/DME RWY 23" for the S-ILS
and S-LOC/DME and CIRCLING/DME. The first plate won't have the 1160
restriction, but will instead allow you to descend to the MDA after BELCH,
and the second will have a step down fix.

I'm not sure if having two plates for the same ILS will help or hurt
matters.

Personally, I wonder why they just don't move the step down fix closer to
the MAP, and make the intermediate altitude 900 feet. That was my first
reaction to Tim's first answer, and one that was suggested by John in his
followup question. But since Tim's first answer about the step-down fix
had some mention of preventing people from busting the circling MDA, I
doubt that this would satisfy that goal.


--
Paul Tomblin http://xcski.com/blogs/pt/
When the revolution comes, we'll need a longer wall.
-- Tom De Mulder

wrote
Without the special knowledge gained by the Air Force explanation, how could
you conclude that. The 2.5 DME stepdown states 1160. Descending to 900
after the FAF because I don't have DME would cause me to have a major pucker
factor and is contrary to every FAA-developed IAP.

If that is what the Air Force intends, then the chart should state, "Non DME
equipped aircraft using LOC minimums may descend to 900 after Belch.

Recall that you picked a nit on me, claiming the error was in the
design of the procedure rather than the charting. I maintain that
given the AF explanation, this is a charting error rather than a
procedural design error since 900 is a safe altitude at any point
after BELCH.

Also, this business of Air Force pilots tracking is pure drivel; this
procedure is for civil use.

Concur. The logical solution is to track the localizer SW course,
which will assure a 228 track. It's simply not stated as such.

And, the hold-in-lieu pattern is screwed up. It should state "one minute" in
the profile view for non-DME aircraft.

Concur.

Further, since this is a RADAR
REQUIRED (not radar required or....) radar vectors are the entry method for
such an IAP.

Not necessarily. I've seen approaches that have an IAF and can be
flown without RADAR assistance but still say RADAR REQUIRED. The
VOR-B at LVJ is one example.

Michael

After all this haggling and confusion, I'll bet Paul is flying to BAF!!

Michael wrote:

wrote
Without the special knowledge gained by the Air Force explanation, how could
you conclude that. The 2.5 DME stepdown states 1160. Descending to 900
after the FAF because I don't have DME would cause me to have a major pucker
factor and is contrary to every FAA-developed IAP.

If that is what the Air Force intends, then the chart should state, "Non DME
equipped aircraft using LOC minimums may descend to 900 after Belch.

Recall that you picked a nit on me, claiming the error was in the
design of the procedure rather than the charting. I maintain that
given the AF explanation, this is a charting error rather than a
procedural design error since 900 is a safe altitude at any point
after BELCH.

It is an error in the design of the procedure. I have no way of knowing I can
"bust" the 2.5 DME altitude unless there is a procedural data note to tell me
that. Some Air Force guy's response on this forum hardly fills that bill!

A charting error occurs when NACO or Jeppesen does not correctly chart what is on
the source 8260-3 or -5. That is not the case here.



Also, this business of Air Force pilots tracking is pure drivel; this
procedure is for civil use.

Concur. The logical solution is to track the localizer SW course,
which will assure a 228 track. It's simply not stated as such.

And, the hold-in-lieu pattern is screwed up. It should state "one minute" in
the profile view for non-DME aircraft.

Concur.

Further, since this is a RADAR
REQUIRED (not radar required or....) radar vectors are the entry method for
such an IAP.

Not necessarily. I've seen approaches that have an IAF and can be
flown without RADAR assistance but still say RADAR REQUIRED. The
VOR-B at LVJ is one example.

This is what the 8260.19C has to say about it,

(2) Where radar is the only method for procedure entry from the en route
environment, enter the following: "Chart planview note: RADAR REQUIRED."

The fact you can find a procedure that doesn't comply with that requirement only
speaks to the fact the feds do make mistakes.



Michael