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

On Mar 10, 9:42*pm, Padraig wrote:

*But either way, if I'm flying the
ILS approach, the DH is the missed approach point. *Once I hit that
altitude and I'm on the glide slope, I'm at the MAP. *So I don't need
timing at all for the ILS, just if I were doing the localizer.

We may have answered our own question talking this out. DME required
for the LOC approach. Plate is for either ILS or LOC.

No glide slope for a LOC appraoch :-) to determine DH.

wrote:
On Mar 10, 9:42 pm, Padraig wrote:


But either way, if I'm flying the
ILS approach, the DH is the missed approach point. Once I hit that
altitude and I'm on the glide slope, I'm at the MAP. So I don't need
timing at all for the ILS, just if I were doing the localizer.


We may have answered our own question talking this out. DME required
for the LOC approach. Plate is for either ILS or LOC.

No glide slope for a LOC appraoch :-) to determine DH.

There is a timing table to determine the LOC MAP.

On Mar 11, 5:10*pm, Sam Spade wrote:

No glide slope for a LOC appraoch :-) to determine DH.

There is a timing table to determine the LOC MAP.

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.

wrote:
On Mar 11, 5:10 pm, Sam Spade wrote:


No glide slope for a LOC appraoch :-) to determine DH.

There is a timing table to determine the LOC MAP.


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.

On Mar 11, 8:09*pm, Sam Spade wrote:
wrote:
On Mar 11, 5:10 pm, Sam Spade wrote:

No glide slope for a LOC appraoch :-) to determine DH.

There is a timing table to determine the LOC MAP.

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.

wrote:
On Mar 11, 8:09 pm, Sam Spade wrote:
wrote:
On Mar 11, 5:10 pm, Sam Spade wrote:
No glide slope for a LOC appraoch :-) to determine DH.
There is a timing table to determine the LOC MAP.
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.

Please correct me if I'm wrong as I'm just working on my instrument
rating. On a localizer approach you never descend below MDA unless you
have the airport environment in sight. Timing is not required on an
ILS, but it's a good idea to start the timer anyway in case you lose the
glide slope (out of action, not too high/low) and have to revert to a
localizer approach. You never descend below the DH on an ILS unless you
have the airport environment in sight. MAP is determined by being on
glide slope and at DH. Cruising down the glide slope at 68 is just fine
as long as you stay on the glide slope. ("Just fine" may vary depending
on who is behind you.) The timer (not required) will expire, but DH is
determined by altitude, not time or DME anyway?

But I'm with the OP in wondering why DME is required. Timing seems to
work for most other localizer approaches to determine MAP, all the
intersections and the missed approach holding points are determined by
VOR radials.

Jim wrote:

wrote:

On Mar 11, 8:09 pm, Sam Spade wrote:

wrote:

On Mar 11, 5:10 pm, Sam Spade wrote:

No glide slope for a LOC appraoch :-) to determine DH.

There is a timing table to determine the LOC MAP.

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.


Please correct me if I'm wrong as I'm just working on my instrument
rating. On a localizer approach you never descend below MDA unless you
have the airport environment in sight. Timing is not required on an
ILS, but it's a good idea to start the timer anyway in case you lose the
glide slope (out of action, not too high/low) and have to revert to a
localizer approach. You never descend below the DH on an ILS unless you
have the airport environment in sight. MAP is determined by being on
glide slope and at DH. Cruising down the glide slope at 68 is just fine
as long as you stay on the glide slope. ("Just fine" may vary depending
on who is behind you.) The timer (not required) will expire, but DH is
determined by altitude, not time or DME anyway?

But I'm with the OP in wondering why DME is required. Timing seems to
work for most other localizer approaches to determine MAP, all the
intersections and the missed approach holding points are determined by
VOR radials.

The DME requirement is most likely an error. The FAA designers make
plenty of mistakes.

wrote:
On Mar 11, 8:09 pm, Sam Spade wrote:

wrote:

On Mar 11, 5:10 pm, Sam Spade wrote:

No glide slope for a LOC appraoch :-) to determine DH.

There is a timing table to determine the LOC MAP.

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.

There are bunches of IAPs with timing tables but no DME. There is a
buffer in TERPs for timing errors. But, you obviously don't understand
any of this.

On Mar 12, 9:24*am, Sam Spade wrote:
wrote:

There are bunches of IAPs with timing tables but no DME. *There is a
buffer in TERPs for timing errors. *But, you obviously don't understand
any of this.

Show me one that doesn't have a DME and NO intersecting radial or
intersection to identify the MAP.

I would be interested in this.

" 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)