G'day all, hope you're all having a great flying day!
I would like to open discussion on a topic that's currently a hot topic for IPCs.
I recently saw some feedback on instrument flying and am concerned that it may be wrong for the debrief point.
The question is basically, can a lower category aircraft, such as a helicopter (CAT A/H), use a higher category such as CAT-D circling area and speed?
I am talking OCTA, rather than having to get ATC clearance to use CAT D.
E.g. you are coming in on a DME/GNSS arrival to circle to land on the runway at Mackay, you have broken visual at night, but instead of having to descend all the way down to the CAT-A MDA and be within 1.68Nm, you want to break off into the CAT-D circling area at 5.28Nm and remain at the CAT-D MDA which is higher. You also want to keep the speed on until you are ready to slow down, so not having to restrict A/S to 100. Obviously if you were still in cloud, you'd require to be 70-100KTS and therefore could keep descending down to CAT-A until visual.

This is way more commercially efficient as you don't have to slow down and can safely manoeuvre a little further out to align with the landing runway.

Can we just use it, or does it have to be in the company ops manual approved by CASA that we can conduct this?
The regulation only refers to operating at a lower category. Which makes complete sense. You wouldn't want a 737 doing a CAT-A approach!

Part 91 General operating and flight rules
Subpart 91.D Operational procedures
Division 91.D.4 Flight rules
Regulation 91.320
(2) A person commits an offence of strict liability if the person contravenes subregulation (1).
Penalty: 50 penalty units.
91.320 Specified aircraft performance categories
(1) The operator of an aircraft contravenes this subregulation if, while the aircraft is operating at an aerodrome:
(a) the aircraft does not operate in the specified aircraft performance category for the aircraft at the aerodrome; and
(b) the operator:
(i) does not hold an approval under regulation 91.045 for the aircraft to operate in a lower aircraft performance category for the aircraft at the aerodrome; or
(ii) holds an approval under regulation 91.045 for the aircraft to operate in a lower aircraft performance category for the aircraft at the aerodrome but does not comply with subregulation (3) of this regulation.
(2) The operator of an aircraft contravenes this subregulation if:
(a) the operator holds an approval under regulation 91.045 for the aircraft to operate in a lower aircraft performance category for the aircraft at the aerodrome; and
(b) the aircraft does not operate in that lower aircraft performance category.
(3) The operator must give details to the flight crew of:
(a) the approval; and
(b) the conditions (if any) imposed by CASA on the approval.
(4) A person commits an offence of strict liability if the person contravenes subregulation (1) or (2).
Penalty: 50 penalty units.

ACCEPTABLE MEANS OF COMPLIANCE AND GUIDANCE MATERIAL
Part 91 of CASR
GM 91.320 Specified aircraft performance categories
The specified aircraft performance category is used to determine the following operational
matters:
• instrument approach aircraft handling speeds
• instrument approach minima.
When operating in a specified aircraft performance category, the PIC must comply with
obstacle clearance, instrument approach speed limits, circling area limits and landing minima
for the category.
A reference to 'lower performance category' is determined by the hierarchy of specified
aircraft performance categories whereby CAT E is the highest and CAT A is the lowest.

AIP 1.5-5 1.2.2
States that aircraft must increase category when actual handling speeds are in excess of those for category (Based on Vat).

So an A109 doing 150KTS still is in the CAT D final approach speed range.

In summary, I believe there isn't a rule to say you can't operate at a higher category (e.g. CAT-D) just as there IS a rule to say you can't operate at a lower category.
AIP also states that you must increase category when actual handling speeds are in excess.
It is completely safe to stop descent at CAT-D and circle at night from 5.28Nm.

I believe the person making the feedback that we should be using the CAT-A circling approach areas (in particular at night) is incorrect. During the day you can just call visual and make a visual approach, so daytime is irrelevant unless IMC conditions exist all the way down until CAT-A MDA.

Part 91 Plain English Guide
Page 106 | OPERATIONAL RULES
Instrument approach operational requirements (MOS 14.09)
When conducting an IAP in IMC you must ensure that the aircraft is operated within a range of, or not more than the maximum speeds in the Table18 A below that is associated with the aircraft performance category.
Exception: You may fly the aircraft in a higher performance category.
To fly the aircraft in a lower performance category the operator must hold an approval and the operator must give the details to the flight crew of the approval and the conditions (if any) imposed by CASA. (91.320):
Note: For example, an aircraft whose specified aircraft performance category is B, may conform to the requirements of aircraft performance category C. But an aircraft whose specified aircraft performance category is C must not attempt to conform to the requirements of aircraft performance category B without CASA approval and operator compliance with 91.320.

So there you have it folks!
I have answered my own question.

You always have had the option of conforming to a category higher than the aircraft is cleared to as that is a more conservative operation. In extremis, you could choose to operate in VMC to IFR procedures when flying your letdown .. although this would defeat some of the value of the IFR operation ?

However, it is all or nothing - if you wish to adopt a higher category, you conform to all the relevant requirements. Of course, you can do something like remain at the more restrictive cat but adopt, say, higher visibility than your category requires to make a particular circling approach a little less sweaty. We used to do this sort of thing routinely.

If you want to operate to a reduction in category you would need to have a specific approval. Given that circling approaches are fairly demanding exercises in minimum ceiling and visibility conditions, I don't see much interest in operating to a lower category except, perhaps, at a particular aerodrome for which an operator may see some value is adopting a particular more restrictive parameter. Many operators have gone the other way and just proscribe circling approaches altogether. When I was flying with Ansett, TAA, for example, did away with circling approaches - the training and recency requirements, allied with the elevated risk, was deemed not worth the relatively small commercial/operational benefit to be gained by using circling approaches. Ansett, on the other hand, saw a commercial value in being able to operate (the F27, particularly) off circling approaches. The end result was that, sometimes, we might be able to land while the blue tail ship either had to hold or divert.

Be assured, though, circling approaches, especially in minimum ceiling and visibility conditions at aerodromes with a few lumpy bits of ground around, are NO fun at all and the closest the civil pilot will get to experiencing the heart rate increases enjoyed by our Naval cousins during night/bad weather carrier operations.