CAT IIIC minimums

From FAA's 2004 Instrument Procedures Handbook, chapter 5:
[...]
The weather conditions encountered in CAT III opera-
tions range from an area where visual references are
adequate for manual rollout in CAT IIIa, to an area
where visual references are inadequate even for taxi
operations in CAT IIIc. To date, no U.S. operator has
received approval for CAT IIIc in OpsSpecs.
[...]

But I heard that airlines are not only authorized, but required
to do an auto-land every so often. Am I missing something here?

Andrey


Jim Carter wrote:

-----Original Message-----
From: Andrey Serbinenko ]
Posted At: Sunday, August 06, 2006 2:42 PM
Posted To: rec.aviation.ifr
Conversation: CAT IIIC minimums
Subject: CAT IIIC minimums

A question: the landing minimums section for ILS CAT-III approaches
may have separate lines for A, B, and C. In some cases the C line
has an "NA" for visibility, and on some other plates the whole C
line is missing. So, what's the difference? Does "NA" mean "not
authorized", i.e. CAT-IIIC cannot be used?

Thanks!


Andrey

Can you give us a particular plate or approach to reference please?

You don't need CAT IIIc for autoland. Cat IIIa is sufficient. I'm
sure one of the airline drivers will chime in - ceiling/visibility
ignored for a moment, can't you autoland off a normal CAT I ILS if you
so desire? It's the same LOC/GS as the CAT III beam, right? They
just flight and obstacle check to a greater tolerance for the CAT III
authorization?


On Mon, 07 Aug 2006 04:37:55 +0000, Andrey Serbinenko
wrote:

From FAA's 2004 Instrument Procedures Handbook, chapter 5:
[...]
The weather conditions encountered in CAT III opera-
tions range from an area where visual references are
adequate for manual rollout in CAT IIIa, to an area
where visual references are inadequate even for taxi
operations in CAT IIIc. To date, no U.S. operator has
received approval for CAT IIIc in OpsSpecs.
[...]

But I heard that airlines are not only authorized, but required
to do an auto-land every so often. Am I missing something here?

Andrey


Jim Carter wrote:

-----Original Message-----
From: Andrey Serbinenko ]
Posted At: Sunday, August 06, 2006 2:42 PM
Posted To: rec.aviation.ifr
Conversation: CAT IIIC minimums
Subject: CAT IIIC minimums

A question: the landing minimums section for ILS CAT-III approaches
may have separate lines for A, B, and C. In some cases the C line
has an "NA" for visibility, and on some other plates the whole C
line is missing. So, what's the difference? Does "NA" mean "not
authorized", i.e. CAT-IIIC cannot be used?

Thanks!


Andrey

Can you give us a particular plate or approach to reference please?

Peter Clark wrote:

You don't need CAT IIIc for autoland. Cat IIIa is sufficient. I'm
sure one of the airline drivers will chime in - ceiling/visibility
ignored for a moment, can't you autoland off a normal CAT I ILS if you
so desire? It's the same LOC/GS as the CAT III beam, right? They
just flight and obstacle check to a greater tolerance for the CAT III
authorization?


It depends upon an airline's ops specs and flight ops policy.
Autolanding on a non-CAT III ILS does not assure containment on the
runway, thus the weather better be sufficient to see if things are not
working out.

ignored for a moment, can't you autoland off a normal CAT I ILS if you
so desire? It's the same LOC/GS as the CAT III beam, right? They

If I remember correctly, the glide slope reception and usability for
vertical guidance are only guaranteed above DA for the approach. So,
I'd assume CAT I and CAT II beams don't officially reach the surface
of the runway.

Andrey


just flight and obstacle check to a greater tolerance for the CAT III
authorization?


On Mon, 07 Aug 2006 04:37:55 +0000, Andrey Serbinenko
wrote:

From FAA's 2004 Instrument Procedures Handbook, chapter 5:
[...]
The weather conditions encountered in CAT III opera-
tions range from an area where visual references are
adequate for manual rollout in CAT IIIa, to an area
where visual references are inadequate even for taxi
operations in CAT IIIc. To date, no U.S. operator has
received approval for CAT IIIc in OpsSpecs.
[...]

But I heard that airlines are not only authorized, but required
to do an auto-land every so often. Am I missing something here?

Andrey


Jim Carter wrote:

-----Original Message-----
From: Andrey Serbinenko ]
Posted At: Sunday, August 06, 2006 2:42 PM
Posted To: rec.aviation.ifr
Conversation: CAT IIIC minimums
Subject: CAT IIIC minimums

A question: the landing minimums section for ILS CAT-III approaches
may have separate lines for A, B, and C. In some cases the C line
has an "NA" for visibility, and on some other plates the whole C
line is missing. So, what's the difference? Does "NA" mean "not
authorized", i.e. CAT-IIIC cannot be used?

Thanks!


Andrey

Can you give us a particular plate or approach to reference please?

Andrey Serbinenko wrote:

ignored for a moment, can't you autoland off a normal CAT I ILS if you
so desire? It's the same LOC/GS as the CAT III beam, right? They


If I remember correctly, the glide slope reception and usability for
vertical guidance are only guaranteed above DA for the approach. So,
I'd assume CAT I and CAT II beams don't officially reach the surface
of the runway.

Andrey

The G/S is not used for Autoland below 100 feet, or so. It is all radar
altimetry and computer logic starting at 150 feet, when the system goes
from autoland tracking to autoland align.

Andrey Serbinenko wrote
But I heard that airlines are not only authorized, but required
to do an auto-land every so often. Am I missing something here?

'Autoland' and 'Approach CAT' are two separate subjects. It is true
that 'autoland' is a requirement for the conduct of an approach and
landing if the wx conditions are below CATII minimums, but autoland
can also be used in VFR conditions.

The reason for the requirement to conduct autolandings every so often
(we had that requirement at the old PanAm) is to insure that the
equipment remains in calibration. If the autolandings were not logged,
the equipment had to be removed from the a/c and bench calibrated at
scheduled intervals.

Many of our PanAm B-727s had autoland capability with only a CATII
approach capability.

Bob Moore
ATP B-707 B-727
PanAm (retired)

'Autoland' and 'Approach CAT' are two separate subjects. It is true
that 'autoland' is a requirement for the conduct of an approach and
landing if the wx conditions are below CATII minimums, but autoland
can also be used in VFR conditions.

OK, I see now. Thanks!

Andrey



The reason for the requirement to conduct autolandings every so often
(we had that requirement at the old PanAm) is to insure that the
equipment remains in calibration. If the autolandings were not logged,
the equipment had to be removed from the a/c and bench calibrated at
scheduled intervals.

Many of our PanAm B-727s had autoland capability with only a CATII
approach capability.

Bob Moore
ATP B-707 B-727
PanAm (retired)