KJZI (Charleston Executive, S.C.) ILS RWY 9 DME Required

" wrote
You imply Sam that timing alone is how you determine the MAP. I say
it's not.
DME determines when you can go below MDA which would be at MAP not 3
minutes 12 seconds.

SAY WHAT!!! Let's take a look at the definition of MDA:

"A specified altitude referenced to sea level for a non-precision approach
below which descent must not be made until the required visual reference to
continue the approach to land has been established."

It's pretty clear that we're not supposed to go below the published MDA on
a non-precision approach, unless we can see enough to descend and land. The
MAP has nothing to do with it except that we can't continue the approach to
land after reaching the MAP.

It seems to me that everyone is missing the main point about "DME
Required" is that it is NOT required....normally, that is.

Since The name of the proceedure does not include "DME" as in LOC/DME,
timing is a perfectly acceptable method of determining the MAP for the LOC
approach.

In all cases where timing may not be used, the procedure must be annotated
“timing not authorized for defining MAPt.”

Note where "DME Required" does appear....in the note section about raising
the minimum DA/MDA when the local altimeter setting is not available. I
suspect that the answer to the OP's question is in here somewhere.

Recommended reading

http://www.faasafety.gov/gslac/ALC/l....aspx?id=17273

Some general copy and paste from the Instrument Flying Handbook....

APPROACH CHART NAMING CONVENTIONS
Individual NACO charts are identified on both the top and
the bottom of the page by their procedure name (based on
the NAVAIDs required for the final approach), runway
served, and airport location.

APPROACH CHART NOTES
The navigation equipment that is required to join and fly
an instrument approach procedure is indicated by the title
of the procedure and notes on the chart. Straight-in IAPs
are identified by the navigation system by providing the
final approach guidance and the runway with which the
approach is aligned (for example, VOR RWY 13).
Circling-only approaches are identified by the navigation
system by providing final approach guidance and a letter
(for example, VOR A). More than one navigation system
separated by a slant indicates that more than one type of
equipment must be used to execute the final approach (for
example, VOR/DME RWY 31). More than one navigation
system separated by the word “or” indicates either
type of equipment can be used to execute the final
approach (for example,VOR or GPS RWY 15).

When radar or other equipment is required
on portions of the procedure outside the final approach
segment, including the missed approach, a note is charted
in the notes box of the pilot briefing portion of the
approach chart (for example, RADAR REQUIRED or
DME REQUIRED).

On some nonprecision approaches, the MAP is given as
a fixed distance with an associated time from the FAF to
the MAP based on the groundspeed of the aircraft. A
table on the lower right hand side of the approach chart
shows the distance in NM from the FAF to the MAP and
the time it takes at specific groundspeeds, given in 30-
knot increments. Pilots must determine the approximate
groundspeed and time based on the approach speed and
true airspeed of their aircraft and the current winds along
the final approach course. A clock or stopwatch should
be started at the FAF of an approach requiring this
method.

When a missed approach is executed
prior to reaching the MAP, the pilot is required to continue
along the final approach course, at an altitude
above the DA, DH, or MDA, until reaching the MAP
before making any turns. If a turn is initiated prior to
the MAP, obstacle clearance is not guaranteed.

Bob Moore
ATP CFII
PanAm (retired)

On Mar 12, 9:41*am, Robert Moore wrote:
" *wrote

It's pretty clear that we're not supposed to go below the published MDA on
a non-precision approach, unless we can see enough to descend and land. The
MAP has nothing to do with it except that we can't continue the approach to
land after reaching the MAP.

Bob,

Bear with me on this. Are you suggesting or saying it's ok to go
below MDA BEFORE the MAP????

I was taught NEVER to descend below DH for the ILS or MDA before the
MAP for non precision approaches such as VOR alpha or LOC.

My point to Sam was that timing alone with wind consideration is not
enough to descend below MDA which again I was taught never descend
below BEFORE the MAP.

DME is the constant factor to finding MAP on this approach, not timing
since there are no intersecting radials to identify MAP.

Timing helps but since GS will vary based on wind conditions, timing
ALONE shouldn't be used to determine MAP.

This is what I was taught for what it's worth.

On 3/12/2010 8:51 AM, wrote:
On Mar 12, 9:41 am, Robert Moore wrote:
" wrote

It's pretty clear that we're not supposed to go below the published MDA on
a non-precision approach, unless we can see enough to descend and land. The
MAP has nothing to do with it except that we can't continue the approach to
land after reaching the MAP.

Bob,

Bear with me on this. Are you suggesting or saying it's ok to go
below MDA BEFORE the MAP????

I was taught NEVER to descend below DH for the ILS or MDA before the
MAP for non precision approaches such as VOR alpha or LOC.

Whew...

When is the occasion when you descend below MDA on a non-precision
approach? Isn't it when you have met the requirements of 91.175?
Note: This part of the regs has to do with when you can descend
below MDA on a non-precision approach, among other things.

Are you saying that you were taught not to descend below MDA even
when you have met the requirements for descending below MDA simply
because you haven't yet reached the MAP?

That's a lu-lu of a misunderstanding.


My point to Sam was that timing alone with wind consideration is not
enough to descend below MDA which again I was taught never descend
below BEFORE the MAP.

Hint: You can descend below MDA when you've met the requirements for
doing so, as per 91.175.


DME is the constant factor to finding MAP on this approach, not timing
since there are no intersecting radials to identify MAP.

Timing helps but since GS will vary based on wind conditions, timing
ALONE shouldn't be used to determine MAP.

What? I would ask if you're kidding, but I'm afraid I know the answer
to that.



This is what I was taught for what it's worth.

You might find it useful to find a competent instructor and go over this
with him/her - for your own good.

" wrote

Bear with me on this. Are you suggesting or saying it's ok to go
below MDA BEFORE the MAP????

MAP has NOTHING to do with MDA

I was taught NEVER to descend below DH for the ILS or MDA before the
MAP for non precision approaches such as VOR alpha or LOC.

DA IS the MAP for ILS, You may descend below the MDA ANYTIME that you
see the runway and can execute a safe landing. Most of the time, the
MAP for a VOR/LOC is over the end of the runway...how are you expected
to land from about 500' over the end of the runway?

My point to Sam was that timing alone with wind consideration is not
enough to descend below MDA which again I was taught never descend
below BEFORE the MAP.

You were taught incorrectly. Timing alone is sufficient to define the
MAP, but that has NOTHING to do with descending from the MDA.

Timing helps but since GS will vary based on wind conditions, timing
ALONE shouldn't be used to determine MAP.

Not what the FAA says. Did you read my entire post?

This is what I was taught for what it's worth.

Better get a better instructor. Of course when one thinks about the
Colgon Air crash, that might be kinda hard to do these days.

The FAA Instrument Flying Handbook is available from
http://faasafety.gov/

Bob Moore
CFIIing since 1970

Robert Moore wrote:

" wrote


Bear with me on this. Are you suggesting or saying it's ok to go
below MDA BEFORE the MAP????


MAP has NOTHING to do with MDA

I was taught NEVER to descend below DH for the ILS or MDA before the
MAP for non precision approaches such as VOR alpha or LOC.


DA IS the MAP for ILS, You may descend below the MDA ANYTIME that you
see the runway and can execute a safe landing. Most of the time, the
MAP for a VOR/LOC is over the end of the runway...how are you expected
to land from about 500' over the end of the runway?

My point to Sam was that timing alone with wind consideration is not
enough to descend below MDA which again I was taught never descend
below BEFORE the MAP.


You were taught incorrectly. Timing alone is sufficient to define the
MAP, but that has NOTHING to do with descending from the MDA.

Timing helps but since GS will vary based on wind conditions, timing
ALONE shouldn't be used to determine MAP.


Not what the FAA says. Did you read my entire post?

This is what I was taught for what it's worth.


Better get a better instructor. Of course when one thinks about the
Colgon Air crash, that might be kinda hard to do these days.

The FAA Instrument Flying Handbook is available from
http://faasafety.gov/

Bob Moore
CFIIing since 1970


Problem is, the CFI-Is of today are "children of the magenta line."
Many of them were not taught the fundamentals of approach procedures.

wrote:

On Mar 12, 9:41 am, Robert Moore wrote:

" wrote


It's pretty clear that we're not supposed to go below the published MDA on
a non-precision approach, unless we can see enough to descend and land. The
MAP has nothing to do with it except that we can't continue the approach to
land after reaching the MAP.


Bob,

Bear with me on this. Are you suggesting or saying it's ok to go
below MDA BEFORE the MAP????

I was taught NEVER to descend below DH for the ILS or MDA before the
MAP for non precision approaches such as VOR alpha or LOC.

And, where there is no DME?

http://www.naco.faa.gov/d-tpp/1003/05105VA.PDF

My point to Sam was that timing alone with wind consideration is not
enough to descend below MDA which again I was taught never descend
below BEFORE the MAP.

You were poorly trained, at least as to MAPs based on timing.

DME is the constant factor to finding MAP on this approach, not timing
since there are no intersecting radials to identify MAP.

If DME were mandatory for the MAP then there would not be a timing table.

Timing helps but since GS will vary based on wind conditions, timing
ALONE shouldn't be used to determine MAP.

This is what I was taught for what it's worth.

Not worth much, sadly.

On Mar 12, 1:42*pm, Sam Spade wrote:

This is what I was taught for what it's worth.

Not worth much, sadly.

Sadly to you but worthy enough for me. I haven't hit anything below
me by being taught to err on the side of being higher have I?

I still get in on minimums with my method, so call what you want Sam,
but real world works for me. And altitude is my friend in the full
scheme of things.

For what it is worth, I am instrument rated, and current, and I am with Sam
on this one. You are indeed expected to know what your ground speed is on
final, within a reasonable margin of error, and the timing table (or your
own time/speed calculation) is the correct way to determine the MAP. There
are plenty of LOC approaches without DME, and not that many that actually
require it. The minimums applied here, along with the penalties for no
local altimeter etc are plenty conservative to make this a safe LOC
approach without DME. It could simply be a charting mistake.

If they really meant for DME to be required it would likely be in the name;
ILS or LOC/DME RWY 9.




In article
,
says...



But of course you do know that the timing table is based on GS. * What
if your GS was 68 knots Sam?

DME is your ONLY source to ensure that you are at MAP along WITH
timing. * If you want to descend below MDA based on time alone AND no
DME, I sure wouldn't want to fly with you.

Of course I do NOT know that. *The timing table is for the LOC MAP. *DA
is your MAP for the ILS.

This newsgroup is so lacking in the fundamentals.

You imply Sam that timing alone is how you determine the MAP. I say
it's not.

DME determines when you can go below MDA which would be at MAP not 3
minutes 12 seconds.

Be my guest on descending below MDA at 3:12 without DME Sam. I won't
be in the plane with you as you come up short or even overshoot the
MAP due to headwinds or tailwind considerations.

VOR-DME wrote:

For what it is worth, I am instrument rated, and current, and I am with Sam
on this one. You are indeed expected to know what your ground speed is on
final, within a reasonable margin of error, and the timing table (or your
own time/speed calculation) is the correct way to determine the MAP. There
are plenty of LOC approaches without DME, and not that many that actually
require it. The minimums applied here, along with the penalties for no
local altimeter etc are plenty conservative to make this a safe LOC
approach without DME. It could simply be a charting mistake.

If they really meant for DME to be required it would likely be in the name;
ILS or LOC/DME RWY 9.

No, that is not correct. Several years ago the naming convention was
changed to include DME in the title only when it is required for the
final approach segment. If it is required for the intermediate segment,
or all of initial approach segments (if there is more than one) or the
missed approach segment, it will be a note.

In the case of the procedure that started this thread, DME is required
for the missed approach holding fix, because the crossing radial does
not pass flight inspection below 6,000. The crossing radial should not
be shown in that case, but the procedures staff keeps it on there hoping
that maintenance will eventually get it fixed so they remove the DME
note. Yes, convoluted and confusing.