Missed approach (?) when glideslope fails

Tauno Voipio wrote:
Steven P. McNicoll wrote:

"Bob Moore" wrote in message
. 122...

Well Steven, why don't you just come right out and tell them
about the Middle Marker?



Because they're disappearing.



There should be a co-located (and associated) DME if
there are no markers, and in can be used instead of the markers.

In the USA, the MM used to be a required part of the ILS system. Now,
nothing is required to replace the MM (not even DME), so most have been
removed.

John

JPH wrote:
Tauno Voipio wrote:

Steven P. McNicoll wrote:

"Bob Moore" wrote in message
. 122...

Well Steven, why don't you just come right out and tell them
about the Middle Marker?



Because they're disappearing.




There should be a co-located (and associated) DME if
there are no markers, and in can be used instead of the markers.

In the USA, the MM used to be a required part of the ILS system. Now,
nothing is required to replace the MM (not even DME), so most have been
removed.


It's a weird interpretation of the ICAO rules, but that would
not be the first time FAA does not respect the internationally
accepted rules.

I'll check from the relevant ICAO docs as soon as I get to
the office.

AFAIK, there should be at least either operative outer
and middle marker or a co-located DME. The markers are
positioned so that outer marker is roughly at the crossing
of the intermediate approach altitude and glideslope
(the point where glide starts) and middle marker at
the crossing of glideslope and MDA.

--

Tauno Voipio
tauno voipio (at) iki fi

Steven P. McNicoll wrote:

Hilton wrote:
I'm a CFI-I.

I find that rather hard to believe.

Steven, I really enjoy reading your posts. I think you bring a lot of
knowledge to these NGs. It's a real pity that you have to resort to insults
to try make a point.

[zap]
Let's assume that the GS fails at 2700' (MSL), the DH is at 357' (MSL),
a
3 degree glideslope, an 'ILS' airspeed of 100 knots, a climb airspeed of
80
knots. For simplicity, let's assume no wind conditions.


Simple. I'm 2300' above DH when the GS fails (I'm rounding off to the
nearest hundred), 2300 divided by 300 is 8 miles (Inside the FAF and still
8
miles from the MAP? Where is this approach?)

Try ACV ILS 32 - it starts you at 5200 - I made it easy for you.


8 miles at 80 knots will take
6 minutes. Now let's use the actual numbers to see how accurate that is.
2700' less 357' is 2343' above DH, 2343' at 318' per mile makes it 7.4
miles
from the MAP, 7.4 miles at 80 knots takes 5.6 minutes. In your no wind
condition I'd have overshot the MAP by 3600', I'm probably over the
runway.

OK, so you suggest teaching IFR pilots that *while they are doing important
stuff* that I mentioned before (power, gear, cowl flaps etc), they have to
do this math in their heads:

(2700-357) / 300 * 60 / 80 = 6 minutes.

And getting back to my original comment, no, I don't think that every IFR
pilot is able to make these calculations correct 100% of the time - hence
the comment about luck. I certainly wouldn't guarantee myself that I could
get these calculations correct 100% of the time during the 'missed'
high-workload portion of the flight. I know and understand my limitations
(there Steven, huge opportunity for another snide remark ), and I'm
willing to do anything that will reduce my workload and that of my students
in IMC during a high-risk part of the flight.

Hilton

Tauno Voipio wrote:

There should be a co-located (and associated) DME if
there are no markers, and in can be used instead of the markers.

In the USA, the MM used to be a required part of the ILS system. Now,
nothing is required to replace the MM (not even DME), so most have
been removed.



It's a weird interpretation of the ICAO rules, but that would
not be the first time FAA does not respect the internationally
accepted rules.

I'll check from the relevant ICAO docs as soon as I get to
the office.

AFAIK, there should be at least either operative outer
and middle marker or a co-located DME. The markers are
positioned so that outer marker is roughly at the crossing
of the intermediate approach altitude and glideslope
(the point where glide starts) and middle marker at
the crossing of glideslope and MDA.


When DME is used as a substitute for the Outer Marker (OM) in the USA,
it doesn't even have to be co-located. As long as the DME source is
within 6 degrees of the final course, it can be used as a replacement
for the OM (Even more if the FAA provides a waiver).
For the military, they only require that the DME be within 23 degrees of
the final course. Many airports use VORTACs or VOR/DME facilities to
provide the DME for an ILS localizer FAF. The FAA's policy is that if
DME is available, it will be used to provide a localizer FAF at the same
point as the glideslope intercept point (called a PFAF), and the OM or
LOM will no longer be used if the DME is available (most do not allow a
common PFAF, because they are not perfectly placed at the point where an
even 100' altitude increment and the glideslope are overhead. In other
words, the glideslope altitude at the OM might be 2367, but the PFAF
will be placed at either the 2400 or 2300 point, and DME will be used
instead of the OM.
The downside is that there are a lot more approaches getting the title
"ILS or LOC/DME" instead of "ILS or LOC" because of this, requiring DME
in order to fly the localizer procedure.
The FAA policy is if the DME is out of service, the ILS (precision) can
still be flown, because the glideslope intercept defines where the final
approach begins, and DH defines where missed approach begins.
This is part of the reason for this current discussion; many procedures
have no way of marking the LOC missed approach point in the USA other
than the time-distance table, because no MM or DME is available.

John

On Sun, 11 Sep 2005 20:38:20 GMT, Tauno Voipio
wrote:

AFAIK, there should be at least either operative outer
and middle marker or a co-located DME. The markers are
positioned so that outer marker is roughly at the crossing
of the intermediate approach altitude and glideslope
(the point where glide starts) and middle marker at
the crossing of glideslope and MDA.

Even if there is, I thought that we are talking about the case where
you don't have a MM, the GPS is broken, you aren't carrying DME (since
US regs allow GPS substitution for DME, with a few exceptions) and you
just lost your glideslope somewhere on the approach, and how you could
then identify the MAP.

"Tauno Voipio" wrote in message
...

It's a weird interpretation of the ICAO rules, but that would
not be the first time FAA does not respect the internationally
accepted rules.


Just like many other nations.

"Peter Clark" wrote in message
...

Even if there is, I thought that we are talking about the case where
you don't have a MM, the GPS is broken, you aren't carrying DME (since
US regs allow GPS substitution for DME, with a few exceptions) and you
just lost your glideslope somewhere on the approach, and how you could
then identify the MAP.


Me too.

On Sun, 11 Sep 2005 20:50:46 -0400, Peter Clark
wrote:

On Sun, 11 Sep 2005 20:38:20 GMT, Tauno Voipio
wrote:

AFAIK, there should be at least either operative outer
and middle marker or a co-located DME. The markers are
positioned so that outer marker is roughly at the crossing
of the intermediate approach altitude and glideslope
(the point where glide starts) and middle marker at
the crossing of glideslope and MDA.

Even if there is, I thought that we are talking about the case where
you don't have a MM, the GPS is broken, you aren't carrying DME (since
US regs allow GPS substitution for DME, with a few exceptions) and you
just lost your glideslope somewhere on the approach, and how you could
then identify the MAP.

In the examples you gave at BED, there would be no need to ID the MAP prior
to executing the missed approach.

For those where it is necessary, other methods have been mentioned in this
thread.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Hilton wrote:



Firstly, please note that after the word "butt", I had "(it may be less
dramatic when surrounded by flatter terrain)." So, we're assuming
mountainous terrain or other nearby obstacles.

When would you start flying the missed?
How would you start flying the missed?
Are you guaranteed to be flying the missed approach as published?

You start climbing when the G/S fails. That is flying the missed even
though you have not reached the MAP (DA point with ILS)

If the missed approach track is straight ahead you are home free.
If the missed approach is a track reversal back to the LOM or a VOR
behind you, you are also home free because all the airspace is protected
from the P-FAF to the DA point (plus 1.5 miles after that) on the turn side.

If the turn is less than a 180 (or thereabouts) then the simple math
Stephen suggests will get you well within protected missed approach
airspace.

And, who knows, you might be at a location where ATC can help you with
radar. ;-)

This is the 21st Century, so anybody who doesn't have GPS to preempt
these types of "1950s" problems probably needs to find another, safer
hobby. ;-)

"Hilton" wrote in message
ink.net...

Steven, I really enjoy reading your posts. I think you bring a lot of
knowledge to these NGs. It's a real pity that you have to resort to
insults to try make a point.


I don't resort to insults, I use facts and logic to make my points. I truly
do find it hard to believe that someone with your knowledge of ILS could be
a CFI-I.



Try ACV ILS 32 - it starts you at 5200 - I made it easy for you.


That's very interesting. Let me make sure I understand your position.
You're saying that if the GS fails when I'm in IMC at 2700 MSL on the ACV
ILS RWY 32 approach I'm screwed and only luck will save my butt if I haven't
started the timer. Is that correct? Do you really teach your students to
begin timing an ILS at the precision approach FAF? Most pilots start the
clock at the nonprecision approach FAF, that's the one used in the timing
table. But at 2700 MSL on the glideslope the nonprecision approach FAF,
ACATA, is still three miles ahead. I don't have to do any arithmetic at all
to determine my distance from the MAP, I can just start the clock when I
reach ACATA. But I don't even have to do that, I can identify the MAP with
DME or ADF or marker beacon.

By the way, DH on that approach is 418 MSL, not 357.



OK, so you suggest teaching IFR pilots that *while they are doing
important stuff* that I mentioned before (power, gear, cowl flaps etc),
they have to
do this math in their heads:

(2700-357) / 300 * 60 / 80 = 6 minutes.


You still don't get it. This isn't an argument about timing vs. not-timing
an ILS. You claimed you're screwed if you don't time an ILS and the GS
fails, we're just trying to show you that that's not the case. Do you now
understand why your position was incorrect?



And getting back to my original comment, no, I don't think that every IFR
pilot is able to make these calculations correct 100% of the time - hence
the comment about luck. I certainly wouldn't guarantee myself that I
could get these calculations correct 100% of the time during the 'missed'
high-workload portion of the flight. I know and understand my limitations
(there Steven, huge opportunity for another snide remark ), and I'm
willing to do anything that will reduce my workload and that of my
students in IMC during a high-risk part of the flight.


But you think any IFR pilot can determine the distance from the MAP to the
precision approach FAF and correctly compute the time required to cover it
00% of the time. Apparently arithmetic is only a problem when it's used to
prove you wrong.