CASA views on Runway Maintainance

[mullokintyre]

The council owned airport at YSHT Shepparton Airport is going to get a new all singing all dancing taxiway that will run parallel to he northern end of 18/36.
At the the last aerodrome committee of management meeting, the council engineer said that the council would close the airport for six weeks while construction was going on.
I suspect we are being fed a bull**** line here, as I distinctly remember some years ago flying into Cunnamulla airport and landing beyond a displaced threshold and final was over the top of machinery.
They said something about the infringement on the runway splay by a fence.
But of course when the taxiway is operational, aircraft taxiing will infringe on the splay of any aircraft landing , so thats a a bit of a furphy.
Is anyone out there in airport land who has been thru a similar construction phase without having to completely close the airport?
Mick

[Vag277]

Why not look at Part 139 MOS to understand the obstacle limitation surfaces - splay angles, widths and heights

[RedwireBluewire]

They constructed a full length parallel taxyway here in Mareeba (YMBA) without closing the runway.
It was reduced length for quite a while, but not closed.
Runway was also extended

[Squawk7700]

I would suggest that the issue lies around the licensing of the airport and the requirements for night flight, IFR flights, 5,700kg+ requiring certain splay angles and obstacle clearances.

I would attempt consultation and raise the possibility of a NOTAM for the period which would rule out a GPS approach and NVFR ops and allow for day VFR only.

The HEMS units would be affected, but no worse than closing it off completely.

[Duck Pilot]

As long as the works are promulgated by a NOTAM with any reduced runway lengths and information about taxiway closures etc, it shouldn’t be a problem.

Not sure why CASA would need to get involved, however this is Australia......

As far as Part 139 and RPT ops go, the onus should be on the AOC holder to decide whether it’s suitable to continue to operate into an aerodrome that’s undergoing maintenance/upgrade, not CASA or the Part 139 holder.

[Vag277]

I suggest you familiarise yourself with obstacle clearance requirements for regulated aerodromes and instrument approach procedures, Part 139 holder is legally responsible to maintain OLS clearances

[Vag277]

Mareeba has only one IAP so OLS can be managed

[CASR139]

I'm not sure what part of the aerodrome operator's comments you believe are false. You don't mention a reason behind their decision to close the aerodrome or that they said they have to close due to works. They might just feel that the risk is too high so they will close down the whole aerodrome.

You and others are correct that there are plenty of ways of managing the risk of aerodrome works to keep and aerodrome open - displaced thresholds, NOTAMs, Works Safety Officers, etc.

But your comments regarding taxiing aircraft infringing the splay aren't accurate for compliant aerodromes. If a taxi route traverses an area "downwind" of a landing threshold, the holding position should be set back such that the holding/taxiing aircraft does not infringe the approach surface (splay). If you were referring to the transitional surfaces (off to the side of the runway), then some aircraft may infringe this surface if the geometry is right (or wrong, depending on your point of view).

Others' comments about OLSs, IAPs and specific operational impacts are little off too. Firstly, certified aerodrome operators are required to establish and monitor the OLS. Maintaining clearances is a little more of a tricky game sometimes. There are plenty of temporary and permanent infringements of OLSs at Aussie aerodromes and the accepted mitigation appears to be displaced threshold, marking, lighting, NOTAM, ERSA or a combination of these. IAPs are a different case with objects assessed against PANS-OPS by the IAP designer and mitigation here will end to be a lifting of minima or other operational restriction.

[Fliegenmong]

"Che
Cheeromulla thank you , not Cunnamulla!

[mullokintyre]

The aerodrome operator is saying the closure is due to CASA requirements. Thats why I asked about other aerodrome 's experiences with upgrades.

[Vag277]

Why not ask what the requirements are? Experiences at other aerodromes are irrelevant unless they are identical layout/dimensions with exactly the same work and Method of Works documentation.

[mullokintyre]

Why not ask what the requirements are? Experiences at other aerodromes are irrelevant unless they are identical layout/dimensions with exactly the same work and Method of Works documentation.

Well, experience suggests that local government withhold information on a consistent basis. Even though the aerodrome management committee (of which i am but one member), is supposed to act as a sounding board between users and Council, what invariably happens is that council employees work out what they want to do and then present it to the aerodrome committee as a "fait accompli". When the council announced to the committee that they were about to conduct a cost benefit analysis on shifting the airport, they withheld the tender details from the committee until the tender was closed. I suspect this was because some of us decided that we would form a group to tender for the work.

[Fieldmouse]

The geometry gets iffy with these code 1A facilities and it depends on the adopted offset from centerline for the new taxiway centerline.
It can legally be down to 37.5m centerline offset.
You throw in the approach / departure baseline being 60m, and the displaced thresholds already there at both ends, and big construction equipment starts to really impact the availability of the aerodrome.
Code C/D/E @ 90-100+ meters centerline to centerline and excavators are suddenly outside the transitional and approach splays and everyone's happy.

Without seeing it I'd have to assume they've made the right call.

[NaFenn]

It all comes down to the operator. CASA has outlined splay requirements in MOS139 including allowances for displaced thresholds to allow runways to remain open etc, however some operators are opposed to displacing runways for several reasons. If the operator can make the numbers work then CASA is happy, however displacing thresholds can be a pain in the ass and is a liability if its done wrong. One operator i know of that does not displace thresholds is Perth Airport who havent had a displaced threshold for years becasue of the 2008 Garuda (https://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-033/) and 2005 South African (https://www.atsb.gov.au/publications/investigation_reports/2005/aair/aair200501819/) incidents where one landed on a closed section of runway and the other had several goes at doing the same. Even now, they close one of the two runways whenever there is runway works.

[Traffic_Is_Er_Was]

They said something about the infringement on the runway splay by a fence.
But of course when the taxiway is operational, aircraft taxiing will infringe on the splay of any aircraft landing , so thats a a bit of a furphy.
When airport people talk about runway splays, they are generally taking about the approach surfaces off the ends of the runways. They are the ones mostly affected by obstacles. The side transition surfaces are the ones affected by taxiing aircraft, and transitory obstacles like those are generally ignored (although addressed by CASA in the licensing). It's permanent obstacles (like a fence or building) they worry about.
Keeping the "splay" of a displaced threshold clear while constructing a parallel taxiway to the closed runway prior to the new threshold may be too onerous, or impose such restrictions that the necessary threshold displacement won't give practical lengths for some necessary operations.
It may simply be that in this case closing the runway for six weeks is cheaper than going through all the B/S of putting in, maintaining, and monitoring a displaced threshold and nearby worksite on an operational airfield.

[mullokintyre]

Thanks to the folk who responded. We had a meeting with the council engineer, and we think we can come up with a plan to shift aircraft around before and after the workers arrive, and minimise disruption to all concerned.
Time will tell whether it is accepted by the powers that be.