Italian VOR/DME Approach

Thanks for your replies, which are interesting and informed as always.

Greg


In article , says...



G Farris wrote:

Sorry about the confusion. I probably should have stated at the outset that
it
was on the last page!!

What perplexes me is not that the airliner did his procedure turn below the
VGSI, but that it's actually published that way.

It's a wierd looking plate. the little X's look like FAF's, except that you
encounter three of them on one approach. Then, the procedure turn is
executed outside the standard 10nm radius, and at a published altitude
below
the VGSI.

I can't think of why they would do it this way, unless it's related to the
military base and their traffic patterns.

ICAO criteria splits approach categories for segments of an approach, unlike
TERPs. That is why the teardrop is tighter for A/B than C/D.

The outer X is the turn limit for C/D. The next X inbound is the turn limit
for
A/B and it is also the intermediate fix where all categories can leave 2100
for
1400. The X at 1400 is the FAF and you will note that is where the descent
table
begins for 260 feet per mile descent gradient.

But, that gradient has you crossing the threshold (1 CAG DME) at 91 feet,
which is
about 40-50 feet higher than what the VGSI is likely sited for. It is all
well
below a 3-degree slope, however.

As far as the outer limits of a procedure turn being below the VGSI, what is
unusual about that? I don't know about Italy but a VGSI in this country is
survey
for obstacles only to 4 miles (VASI) or 3.5 miles (PAPI).

ICAO criteria splits approach categories for segments of an approach,
unlike
TERPs. That is why the teardrop is tighter for A/B than C/D.

The outer X is the turn limit for C/D. The next X inbound is the turn
limit for
A/B and it is also the intermediate fix where all categories can leave
2100 for
1400. The X at 1400 is the FAF and you will note that is where the
descent table
begins for 260 feet per mile descent gradient.

But, that gradient has you crossing the threshold (1 CAG DME) at 91 feet,
which is
about 40-50 feet higher than what the VGSI is likely sited for. It is all
well
below a 3-degree slope, however.

As far as the outer limits of a procedure turn being below the VGSI, what
is
unusual about that? I don't know about Italy but a VGSI in this country
is survey
for obstacles only to 4 miles (VASI) or 3.5 miles (PAPI).


also bear in mind that the process for establishing the glideslope when on
an ILS approach is to join from beneath the glideslope and then track the
glideslope down to DA.

Its the same principle.