[Peetwo]

Request For Change - YCTM - RWY 34

Courtesy CM, via AP emails:

Hi Pip and Jonathan

I’m writing to you, directly, in an attempt to bring to an end some unnecessary risks created by CASA at Cootamundra aerodrome (YCTM). All it would take is the deletion of some words from ERSA, but that ostensibly simple outcome has proved difficult to achieve for a protracted period.

Subsequent to correspondence with CASA, the latest of which occurred on 25 March 25 (below), I have found out that the change to right hand circuits during hours of daylight (HJ) on runway (RWY) 34 at YCTM was the result of a thought bubble on the part of a CASA aerodrome inspector, Mr Iain Bailey. Mr Bailey apparently decided that the change was justified because of his perception of the risk of, and his perceptions of the consequences arising from, different pilots coming to different conclusions as to whether it is HJ or HN (hours of night) at the same location at the same point in time.

I bring to your attention the following points about that perceived risk and its perceived consequences, and the reality, all of which should have become obvious if a proper risk assessment had been conducted by competent persons before the change was made at YCTM.

First, the probability of pilots coming to different conclusions as to whether it is HJ or HN at the same location at the same point in time is remote, particularly so in the 21st century. The information is now literally at pilots’ fingertips via an EFB.

That remote probability then has to be multiplied by the probability of those pilots arriving in the same circuit area at the same time, then multiplied by the probability of those pilots being unaware of each other in the vicinity of a certified aerodrome in the vicinity of which carriage and use of serviceable radios are therefore required, all of which results in a very remote risk.

And in the event of that very remote risk becoming reality and even assuming the pilots choose to do a circuit for the same runway rather than a straight-in approach, which straight-in approach they can now do, irrespective of the mandated circuit direction, the outcome at YCTM – prior to the decision resulting from Mr Bailey’s thought bubble – would be that they end up on downwinds on opposite sides of the runway. One would be on a right downwind for RWY 34 (that pilot believing it’s HN) and the other would be on a left hand downwind for RWY 34 (that pilot believing it’s HJ), thus separating them by a substantial distance.

Then that very remote risk must be multiplied by the probability the pilots not seeing each other during their respective downwinds, nor during their base legs when they are ‘head to head’ at slow (flaps extended) speed. At least one of them thinks it’s HN, so at least one aircraft’s landing lights and strobes are on. (Or do we add ‘forgetting to turn on the landing and anticol lights’ and ‘failure of the landing light and anticol lights’, to the list of remote risks?)

All the while, the pilots are apparently oblivious to whether it is, in fact, HN or HJ where they are, in fact. Looking out the window has somehow escaped, or is been avoided by, the pilots.

All of those probabilities multiply to an infinitesimally small risk, which infinitesimally small risk is obvious to most pilots with a modicum of experience, including all of the pilots with whom I’ve discussed this issue. Our combined aeronautical experience adds up to centuries and tens of thousands of hours.

I understand Mr Bailey has around six thousand hours of ‘commercial experience’. However, I also understand that he has not flown as pilot in command at all in the last six or so years. I suggest that Mr Bailey may have either forgotten some of what he learnt during that commercial experience, or that his experience didn’t include many hours operating in and out of non-towered aerodromes around the end of civil daylight. I’m happy to stand corrected, of course.

I am not aware of any recorded accident or incident caused by pilots coming to different conclusions as to whether it is HJ rather than HN or vice versa at the same certified non-towered aerodrome at the same point in time. I would therefore welcome and read with keen interest any report of an investigation of that kind of incident.

Also obvious to experienced pilots are the risks created by CASA’s decision resulting from Mr Bailey’s thought bubble (even setting aside the infringing obstacle issue, to which issue I will return).

The first of those risks is that in circumstances of zero-to-little wind, it is possible - and common - for pilots to choose different runways. If one pilot chooses to use and join downwind for RWY 16 at YCTM and another chooses, at the same time, to use and join downwind for RWY 34, the outcome of Mr Bailey’s thought bubble is a high risk scenario: aircraft joining opposite downwinds ‘head to head’ at high speed, each being a stationary speck in the other’s windscreen. One is joining a right hand downwind for RWY 34 and the other is joining a left downwind for RWY 16. That risk would not arise if the circuit direction for each RWY were the ‘default’ left hand. It is true that there is a remote risk that the aircraft in this scenario would end up landing ‘head to head’, but in that event they end up at low speed on the runway before the potential collision. More time to ‘see and avoid’, and less damage if they don’t.

If the legitimate mitigators for that risk are the use of radio and see and avoid, they are legitimate mitigators for the risk arising from pilots coming to different conclusions as to whether it is HJ or HN at the same location at the same point in time. However, the substantial difference is that the probability of different pilots choosing different runways in circumstances of little-to-no wind is not remote whereas the probability of pilots coming to different conclusions as to whether it is HJ or HN at the same location at the same point in time is remote. The decision resulting from Mr Bailey’s thought bubble has therefore created at least one new risk with greater probabilities than the one perceived as justifying the change.

The circumstances which justified the imposition, decades ago, of the right hand circuit requirement HN on RWY 34 at YCTM have changed substantially. In fact, the circumstances have changed such that there is increased risk in right hand circuits on RWY 34 at YCTM HN (as well as HJ). This should have been identified in a proper and competent risk assessment.

There is no longer a ‘commuter airline’ operating noisy piston twins out of YCTM. They’re decades gone. The number of movements each night at YCTM can now be counted on the fingers of one hand, and usually on one finger of one hand or no fingers at all. Further, the few HN movements almost invariably involve a straight-in approach, because it is no longer mandatory to fly three legs of a circuit. (My first take-off and landing as a pilot at YCTM was 39 years ago. I now live in and operate out of YTCM, and monitor the CTAF and area frequencies. I know of what I speak.)

The absence of night movements is why the current operator of YCTM, the local council, has not expressed any concern about night time air traffic noise in the vicinity as would justify right hand circuits HN on RWY 34 on noise abatement grounds.

Further, and more importantly, the tallest and closest of the infringing obstacles in the vicinity of YCTM – the telecom tower – was erected after the imposition of the right hand circuit requirement on RWY 34 HN. It is on a bearing of 137 degrees magnetic at a distance of 2,411 metres from the ARP, and infringes the HZS by 185 feet. Only a little further away and not too much shorter is a radio tower on a bearing of 138 degrees magnetic at a distance of 2,457 metres from ARP, which tower infringes the HZS by 146 feet. Both of those obstacles are under or close to the right base leg for RWY 34. There are no infringing obstacles under or close to the left base leg for RWY 34. (At least my original REPCON on this issue apparently precipitated an overdue survey of the terrain and obstacles in the vicinity of YCTM.)

Those infringing obstacles pose little material risk HN, first because of the lack of traffic noted above, secondly because of the use of straight-in approaches by what little traffic there is, again as noted above and, thirdly, because the obstacles are illuminated and, therefore, very easy to see at night. Nonetheless, it is important to note that the removal of the requirement for right hand circuits HN on RWY 34 would move the tiny amount of traffic that might fly a circuit HN away from the only infringing obstacles in the vicinity of its base leg to an area where there are no infringing obstacles.

Mr Bailey apparently takes a different to view than I do, and a different view to every other experienced pilot with whom I’ve discussed the issue, as to the difficulty of spotting obstacles on the ground from the cockpit in the air HJ. It is true that the tallest and closest of the infringing obstacles in the vicinity of YCTM is really easy to spot from the ground during the day. The next closest obstacle is a little more difficult to see from the ground, but still obvious if one knows where to look. And the lights on their tops make them really easy to spot at night.

However, unless one knows that the obstacles are there, they can be difficult to spot during the day, depending on where the sun is, what the cloud conditions are and the way in and direction from which aircraft join the circuit. Further, it is impossible to see anything through an engine cowling or wing. (I’ll stand corrected on the last point if you inform me that Mr Bailey has x-ray vision.)

Further still, lots of pilots will assume – reasonably I suggest – that no competent safety regulator would deliberately make or allow circuit arrangements so as to concentrate descending traffic near the only infringing obstacles in the vicinity of an aerodrome, when an available alternative is the ‘default’ left hand circuits that would result in descending traffic

nowhere near any of the obstacles. (Though I do note that if any right hand circuit is justifiable on any valid grounds at YCTM, it would be on RWY 28. That would not only take its descending base away from the only infringing obstacles, it would also move the only runway downwind leg that is currently above the Cootamundra township to above farm paddocks instead.)

The pilot of a ‘low-performance aircraft’ doing a 500’ circuit, in accordance with CASA’s published guidance, in an aircraft fitted with an altimeter with VFR tolerances, would, I suspect, be surprised and perturbed to learn that someone in CASA decided it is okay to put the pilot on a potential collision course with infringing obstacles on a descending right base for a RWY, when there would be no potential for a collision with any infringing obstacles during a left base for that RWY. YCTM has an elevation of 1,110’. The top of the closest and tallest obstacle is under or near the right base leg of RWY 34. The radio tower nearby that obstacle is more difficult to see and only 41’ shorter. A ‘perfect’ 500’ above YCTM is 1,610’. That’s less than 200’ clearance above the top of tallest obstacle at 1,435’. And the aircraft’s altimeter could be up to 100’ wrong. That’s less than 100’ clearance above the tallest obstacle. And the aircraft could be descending.

Assuming I’m wrong about the difficulty in spotting the obstacles from the air HJ, and the obstacles are, in fact, obvious to all pilots in all circumstances, it does not follow that the obstacles do not pose any risk in any circumstances. Further and in any event, there is no logical or safety-based reason for concentrating traffic anywhere near those obstacles when there is a safer, available alternative in the form of left hand circuits.

What’s happened at YCTM is like prescribing a mandatory navigation route, for ships, across the shallowest water in a harbour, when the route could just as easily be across deeper water. It’s patently – I’m struggling for an adjective usable in polite correspondence, so I’ll opt for – silly.

There is a safety-based reason for the ‘default’ circuit direction being left hand, the corollary of which is that requiring right hand circuits entails, in and of itself, increased risk compared with left hand circuits. Many fixed wing aircraft have two seats in the front, and in most cases the pilot in command of those aircraft sits in the left hand seat. Left hand circuits give the pilots a better view of the manoeuvring area compared with right hand circuits. That is why Part 139 MOS says PAPI should be on the left side of a runway. That is why Part 139 MOS says a threshold wind indicator should be on the left side of a runway.

And those circumstances, among others, are why there should be a safety case supported by a risk assessment carried out by competent people, demonstrating that the reduction in safety inherent in a change to right circuits is outweighed by other considerations, before any decision to change to right circuits is made. My FOI request for access to documents relating to the change at YCTM did not result in the disclosure of any credible safety case or risk assessment in support of the change.

I note that there are many aerodromes at which the circuit direction HN is different to the circuit direction HJ. That fact is expressly acknowledged in CASA’s own advisory material. AC 91-10 v1.3 dated January 2025 notes at page 26:

“At many aerodromes, the circuit direction at night is different to the direction during the day. This is generally because of terrain, obstructions or noise abatement.”

If the potential for different pilots to make different decisions about when it’s HJ or HN at YCTM created risks so great that it justified the new risk of head-to-head downwinds HJ as well as concentrating descending traffic over the only infringing obstacles in the vicinity at YCTM, it would surely follow that the potential creates an unacceptable risk at all other non-towered aerodromes where the circuit direction HN is different to the direction HJ. Yet CASA has approved and is continuing to allow those circumstances to continue at many aerodromes. I am confident that those circumstances have been approved and continue because, among other reasons, the risk perceived by Mr Bailey is infinitesimally remote.

The outcome of CASA’s decision to require right hand circuits HJ on RWY 34 at YCTM is to create unnecessary risks, all of which could easily be avoided by a return to the simple, default rule which has a substantial safety basis. But I now learn that CASA expects to be provided with a risk assessment and justification before CASA will undo its decision. When the operator of the aerodrome issued a NOTAM in an attempt to undo the risks created by CASA, CASA quashed the NOTAM. This is Alice In Wonderland stuff. But pilots like me are put at risk in the real world.

CASA, alone, created unnecessary and avoidable risks at YCTM. And CASA, alone, is now prolonging the existence of those unnecessary and avoidable risks. You are now on actual notice of the circumstances.

Please just get some competent CASA officer/s to arrange for the deletion of a few words from the ERSA entry for YTCM, so as to clean up a mess created by CASA. Please.

I will be submitting another REPCON to ATSB on this issue because it is all a product of CASA’s corporate incompetence.

Regards

Clinton

MTF...P2