BAF LOC 23

I'm trying to figure out the BAF ILS 23 localizer approach. The normal
LOC 23 approach has a MDA of 900, and the LOC 23/DME approach has a MDA of
700 feet. After the FAF, there is a step down fix at 2.7 DME with a
_1160_ before it. So does this mean that if you don't have DME, you can
descend to 900 immediately after the FAF, but if you do have DME you can
only descend to 1160 until 2.7 DME? Why is it safe to descend to 900 in
one case, but only 1160 in the other?

--
Paul Tomblin http://xcski.com/blogs/pt/
My family's values included "Always state your assumptions and your evidence",
"first find out what the problem is, then fix it", and "feed your horse before
yourself". But you don't see people legislating those... -- Zeebee

In article ,
Paul Tomblin wrote:
I'm trying to figure out the BAF ILS 23 localizer approach.

BAF??

--
Ben Jackson

http://www.ben.com/

Paul Tomblin wrote:
I'm trying to figure out the BAF ILS 23 localizer approach. The normal
LOC 23 approach has a MDA of 900, and the LOC 23/DME approach has a MDA of
700 feet. After the FAF, there is a step down fix at 2.7 DME with a
_1160_ before it. So does this mean that if you don't have DME, you can
descend to 900 immediately after the FAF, but if you do have DME you can
only descend to 1160 until 2.7 DME? Why is it safe to descend to 900 in
one case, but only 1160 in the other?


Assuming you mean CEF, not BAF, it does seem to read that way. I agree
it seems odd.

--
David Rind

In a previous article, David Rind said:
Paul Tomblin wrote:
I'm trying to figure out the BAF ILS 23 localizer approach. The normal
LOC 23 approach has a MDA of 900, and the LOC 23/DME approach has a MDA of
700 feet. After the FAF, there is a step down fix at 2.7 DME with a
_1160_ before it. So does this mean that if you don't have DME, you can

Assuming you mean CEF, not BAF, it does seem to read that way. I agree
it seems odd.

Oh yeah, CEF. Wrong bookmark.


--
Paul Tomblin http://xcski.com/blogs/pt/
http://www.pointlesswasteoftime.com/film/50reasons.html
"Apparently they made the beasts [Uruk Hai] by crossing Orcs, Goblins and
the French."

On Sun, 10 Oct 2004 20:37:11 +0000 (UTC),
(Paul Tomblin) wrote:

I'm trying to figure out the BAF ILS 23 localizer approach. The normal
LOC 23 approach has a MDA of 900, and the LOC 23/DME approach has a MDA of
700 feet. After the FAF, there is a step down fix at 2.7 DME with a
_1160_ before it. So does this mean that if you don't have DME, you can
descend to 900 immediately after the FAF, but if you do have DME you can
only descend to 1160 until 2.7 DME? Why is it safe to descend to 900 in
one case, but only 1160 in the other?


I may be completely wrong on this, but I think the 1160 is a step down
for both types. As I see it if you have DME you can proceed lower (to
700) at the 2.7 mile mark, otherwise the radar facility will call the
2.7 mile position for you at which time you can proceed lower to 900.
This may allow for the radar facility to be more inaccurate than the
on board DME. The approach does say Radar Required.

Also, If you proceed to 700 you'll go missed at .9 DME, where as if
you don't have DME. all you have is time. I think they might also
want some added safety for some reason (possibly for clearance of the
390 foot obstacle right near the end of the runway).

There's also 923 foot obstacle just left of course after the FAF that
I'd be very careful to stay above, and is what made me initially think
the 1160 was for both approaches.

Hope this helps. Looking forward to further discussion on this one.

z

"zatatime" wrote in message
...
I may be completely wrong on this, but I think the 1160 is a step down
for both types. As I see it if you have DME you can proceed lower (to
700) at the 2.7 mile mark, otherwise the radar facility will call the
2.7 mile position for you at which time you can proceed lower to 900.
This may allow for the radar facility to be more inaccurate than the
on board DME. The approach does say Radar Required.

....except the step-down fix doesn't include the words "RADAR", indicating
that the controller will call the stepdown.

Come to think of it, I doubt they'd have a radar fix inside the FAF because
at that point, you'd be on or switching to tower, which may or may not have
a radar display in the cab.

Interesting.

"zatatime" wrote in message
...
On Sun, 10 Oct 2004 20:37:11 +0000 (UTC),
(Paul Tomblin) wrote:

I'm trying to figure out the BAF ILS 23 localizer approach. The normal
LOC 23 approach has a MDA of 900, and the LOC 23/DME approach has a MDA of
700 feet. After the FAF, there is a step down fix at 2.7 DME with a
_1160_ before it. So does this mean that if you don't have DME, you can
descend to 900 immediately after the FAF, but if you do have DME you can
only descend to 1160 until 2.7 DME? Why is it safe to descend to 900 in
one case, but only 1160 in the other?

I may be completely wrong on this, but I think the 1160 is a step down
for both types. As I see it if you have DME you can proceed lower (to
700) at the 2.7 mile mark, otherwise the radar facility will call the
2.7 mile position for you at which time you can proceed lower to 900.

That's how I read it too. An MDA doesn't override a prior minimum altitude.
Without radar, there's no way to descend below 1160' (except visually).

Cool example--thanks for posting it, Paul!

--Gary

"Brad Z" wrote in message
news:grjad.224521$D%.88524@attbi_s51...
"zatatime" wrote in message
...
I may be completely wrong on this, but I think the 1160 is a step down
for both types. As I see it if you have DME you can proceed lower (to
700) at the 2.7 mile mark, otherwise the radar facility will call the
2.7 mile position for you at which time you can proceed lower to 900.
This may allow for the radar facility to be more inaccurate than the
on board DME. The approach does say Radar Required.

...except the step-down fix doesn't include the words "RADAR", indicating
that the controller will call the stepdown.

Hm, good point. So maybe there's no way to use the non-DME MDAs.

Interesting.

Indeed.

--Gary

In a previous article, "Gary Drescher" said:
Cool example--thanks for posting it, Paul!

Well, I'm really hoping I'll do the ILS or the visual, but it pays to
prepare.

--
Paul Tomblin http://xcski.com/blogs/pt/
"It is a universal truth that the loss of liberty will be charged to
dangers, real or imagined, from abroad." - James Madison

In article grjad.224521$D%.88524@attbi_s51,
"Brad Z" wrote:

"zatatime" wrote in message
...
I may be completely wrong on this, but I think the 1160 is a step down
for both types. As I see it if you have DME you can proceed lower (to
700) at the 2.7 mile mark, otherwise the radar facility will call the
2.7 mile position for you at which time you can proceed lower to 900.
This may allow for the radar facility to be more inaccurate than the
on board DME. The approach does say Radar Required.

...except the step-down fix doesn't include the words "RADAR", indicating
that the controller will call the stepdown.

Come to think of it, I doubt they'd have a radar fix inside the FAF because
at that point, you'd be on or switching to tower, which may or may not have
a radar display in the cab.

Interesting.



Another strange thing is the missed. I can deal with the "expect radar
vectors" part, but I'm a little confused about the "tracking 228" bit.
I can only assume they mean to track the localizer back course outbound,
but normally they would write that as "climb to 3000 via ICEF back
course" or something like that. Did they really mean 228 heading?

Yet another interesting gotcha is that the DME readouts are all relative
to the CEF VORTAC, not the I-CEF localizer.