Visual Approaches

[blueloo]

After having a look at the AIP definition of Visual Approach and the requirements, someone has pointed out that it may not be as clear cut (or in reality as convoluted) as one expects.

THe definition or requirements say (AIP 1.1 -21 Para 11.5 and 1.5-9 Para 1.14)

For IFR, by day /night within 30nm of the Aerodrome
....
...
Tracking, by day within 5nm of the Aerodrome

or night withn the circling area or within 5nm (7nm ILS) of the aerodrome aligned with RWY C/L etc , or within 10nm (14nm RWY 16L/34L) of the Aerodrome etc...

(I undertsnad this to be based on the surveys of the approach areas..)


The AIP Definition of Aerodrome is (AIP gen 2.2-1)
A defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft.




So my question therefore is (a) where do we find the dimensions of the aerodromes we operate into to apply these distances
(b)from experience most people use the distances based on RWY threshold. Whilst this would be conservative - is using the RWY threshold really suitable (legally) for using the 5nm/7nm/10nm

THe only reason i ask, is that there are some pedantic so & so's out there, who apply the rules as they interpret them, not necessarily (and i dont necessarily know either) as they are intended.

[Capt Fathom]

Well Loo, in 30 years of aviation, I have not come across anyone pedantic enough to bring up that one!
Now back to the Sunday papers with you, and stay away from those AIPs for a while.

[blueloo]

First time i heard about it was yesterday from a mate, i agree pedantic.....but it is an interesting issue....sometimes it helps to be prepared and have some return ammuntion when you have to fly with a pedantic person.

Other times it's just nice to try to figure out the real meaning.



Especially when you hear about people being failed on checks because they used PAPI distances (7nm) on an ILS surveyed RWY (Perth rwy 03) yet they are failed because the use of the ILS is not yet approved.

[Icarus2001]

blueloo It is VERY unlikely that the reason you give is the reason that they failed!

Answer (a) DAP Plates but not really required.

Answer (b) Use the ARP.

blueloo Can I suggest that you apply some perspective here and try to apprecite what the "rule" is trying to achieve. This will usually but not always :rolleyes: provide some insight in to the requirement and more importantly how to apply it in operations.

[John Citizen]

I agree with Icarus.

I believe Distance within aerodrome is based on the ARP (not VOR/DME).

However distance of circling area (based on threshold is a hard one).


To play it safe, it I say, if we are within the circling area based on the ARP, then we are within the circling area based on the threshold (just in case someone wants to be pedantic).

[OverheadPanel]

I am not sure that it is the ARP. More likely these distances would have to be based at least on Threshold (aside from the circling area reference which is based on this)

For example - Sydney 34l - the furthest point of the aerodrome is essentially the threshold (other than the extra bit of grass out to the break water). The aerodrome reference point is around 2 km away!

[I Fly]

Put yourself in 'that pedantic' person's position. How could they measure you were 7.1nm instead of 7.0nm? By DME? There's your answer. By GPS? Tell it to go to YABC and there's your answer. Mark 1 eyeball? I doubt it. And I agree, you would not fail on that alone.

[John Citizen]

I still believe distances (apart from circling area) are based on the Aerodrome Reference Point (ARP).

Take a look at some definitions.

In the AIP, the definition for ARP (http://www.airservicesaustralia.com/pilotcentre/aip2/aip/gen/22121.pdf) is :

The designated geographical location of the aerodrome

For those who use Jeppesen's, take a look at "Introduction page 2".

ARP = A point on the airport designated as the official airport location

To me this is a bit like the Centre of Gravity, where we assume the entire weight of the aeroplane acts through, even though the weight acts through it all the way from the nose to the tail.

The perimeter of an aerodrome may be spread out several miles from the ARP but I believe the ARP is used the same as the aircraft C of G. (assumed to act/be at one point)

[regitaekilthgiwt]

Why go any further then the actual definition of an aerodrome itself as in the AIP.

"Aerodrome: A defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft."

So I guess you are all right :D

I guess there is nothing wrong with using the threshold as this is an installation which will be used for part of the arrival... Mind you when is the ARP used for the arrival?! :confused: lol

[John Citizen]

Lets look up some more in a :
dictionary (http://dictionary.reference.com/)

reference (http://dictionary.reference.com/search?q=reference) = act of refering

refer (http://dictionary.reference.com/search?q=refer) = To direct to a source for information


Therefore I interpret an "Aerodrome Reference Point" being to the "point" to which your refer to the exact location (latitude, longitude) of the aerodrome.


regitaekilthgiwt

You ask :

Mind you when is the ARP used for the arrival?! lol

What is so funny here ? You don't believe the ARP is ever used ?

I use the ARP all the time, with the IFR GPS set up on the ARP (or am I doing something wrong now).

For example, I quite often use the ARP at night to make a visual approach.

The requirements being -
- established within 5nm of aerodrome
- on runway centreline
- not below slope
etc...

[Kaptin M]

Answer to Q(a) - A Jeppessen chart of the aerodrome concerned will display the ARP. If you can't find a Jepp. contact the Dept of Transport (Aviation section), or the local council for the area where the airport is located. They will provide you with a map indicating where the ARP is located.

Answer to Q(b) - The fact that "most people use the distances based on RWY threshold" does not make it correct, and it is NOT correct.

Circling distances are based on the Aerodrome Reference Point, as are those used for prescribing aerodrome limitations (such as noise abatement procedures), and for the defining of each airports boundaries.

[DirectAnywhere]

Sorry Kap.

Circling areas are definitely based on the runway threshold NOT the ARP - OLD Criteria charts excluded.
The circling area is determined by drawing an arc centred on the threshold of each useable runway and joining these arcs by tangent
AIP ENR 1.5.1.7.3 - Note 3 (http://www.airservices.gov.au/pilotcentre/aip/aip/enr/1515.pdf)

[ITCZ]

Agree with DA.

For Jepp Terminal 3.16.1 paragraph a. subparagraph (4) and paragraph b. subparagraph (4), "within the circling area" the definition of circling areas from paragraph 3.13.3 NOTE 3 is used, as per DirectAnywhere's post.

As for the rest of para 3.16.1, every other limiting distance for visual procedures into an aerodrome uses the phrase "Within x NM of that aerodrome".

When the AIP wants to talk about a distance from the threshold, it says so. Here it does not. When the AIP talks about an area defined by distances from thresholds, that is circling areas, it says so. Here it does not. When the AIP talks about distance from the aerodrome boundary, it says so. Again, here it does not.

So where "is" the aerodrome? The aerodrome "is at" the ARP.

So "Within 30NM/5NM/7NM/10NM/14NM of that aerodrome" is within that distance of the ARP.

[Kaptin M]

With reference to an Instrument approach, followed by a circling approach to a specific runway, I agree with you, Direct Anywhere.

I took blueloo's Q & A in the context of a VFR pilot making a Visual Approach.

Jeppessen notes that there there are 2 possibilities for defining the ARP (depending on the type of approach) - one is when the ARP is "Off runway" Center of cross positioned at exact location. In this case a "CIRCLE-TO-LAND" chart (followed by an instrument approach) uses the ARP which is non-runway specific.

The other is "Located on runway centerline. Arrow points to exact location" In this case, the circling minima specifies which runway it applies to.

Cheers.

[Crash & Burn]

Just to keep the thread going a bit longer - a question for those REALLY pedantic people...........

- Are the distances based on slant range or distance over the ground from directly underneath the aircrafts present position???
http://www.pprune.org/forums/images/icons/46.gif http://www.pprune.org/forums/images/icons/mpangel.gif http://www.pprune.org/forums/images/icons/46.gif http://www.pprune.org/forums/images/icons/mpangel.gif http://www.pprune.org/forums/images/icons/46.gif

[Kaptin M]

Which Hemisphere are you enquiring about, C & B??

...which type???...and from which seat????http://pprune.org/forums/images/icons/46.gif :cool: http://pprune.org/forums/images/icons/46.gif :cool: http://pprune.org/forums/images/icons/46.gif

[Crash & Burn]

Ah yes Kaptin M - another very valid question - which part of the aircraft is it measured from ?!?!?! :} :8

[John Citizen]

You ask : - Are the distances based on slant range or distance over the ground from directly underneath the aircrafts present position???

Slant error does not apply to a GPS derived distance (or I don't believe it does - as its not measuring a radio signal on a slant angle the way the DME does).

But lets look at this slant error anyway (just in case you are using a DME to determine your distance).

At 5 DME, at 1500', your actual distance from the DME will be 4.99nm !!

At 30 DME, at 9000', your actual distance from the DME will be 29.96nm !!

As you can see, the slant error is negligible, as its less than 0.1nm.

At 5 DME, the error os 0.01 nm !! Can any DME read the distance to 0.01 nm ?? I never seen one. Is the average DME accurate to 0.1 or 0.01 nm !!

At 250 knots on descent, it will only take to 1.5 seconds to fly this 0.1nm.

Its worth taking note of the fact the the DME measured slant distance will actually put you closer to the aerodrome than the DME reads.

For example, DME reads 30 DME, you are actually at 29.96 nm.

So if anyone wants to be pedantic, you can just reassure them of the fact that you are (0.1 nm at worst) closer then you think you are.

You ask : another very valid question - which part of the aircraft is it measured from ?!?!?!

Lets imagine your aircaft is 70m long, and the DME is measured in the nose but you want to ensure that the entire aeroplane (tail) is contained within the required distance.

Well 70m works out to be 0.038 nm !!

So if you want to be pedantic, you can now delay your descent for a visual approach by 0.04nm (or 0.1nm to be safe).

If you are still doing 250 knots on descent, it will take you 0.55 seconds to fly the length the aeroplane.

So if you want to really pedantic, just delay your descent by 0.1nm or 1 second just to keep you safe.

[Crash & Burn]

Thanks for going to all that trouble John - I feel much better now knowing that effectively the DME slant error cancels out the aircraft length error. I can now descend with confidence!

One less thing to get busted for! :ok:

(And yes I am also of the belief that the GPS is not showing slant range but ground range.)

Cheers

C & B !

[hoss]

Don't get too relaxed just yet.

The GPS is a little'dodgey' for determining the descent (visual approach), full of errors. For example; satellite clock error 0.5m, satellite ephemeris error 0.5m, atmospheric propagation error 4.0m:oh: , instrument/receiver error 1.0m and finally satellite geometry error but I don't want to get started on GDOP,TDOP,PDOP,VDOP and HDOP it's getting too late;) .

Just wanted to warn you guys for planning your descents especially on Checks be careful and have your story ready when the Checky starts to give you a hard time in the de-brief:ok: .

[amos2]

As I spend more time in cretin class than anywhere else these days, it's pleasing for me to know that todays driver in the sharp end is concentrating on the really important leading edge matters! :p

[regitaekilthgiwt]

John,
Not sure why you are referring me to more things about referal, but anyway I digress.

I agree that the ARP is the “point” to which you refer to the exact location of the aerodrome. It has to have a “centre” somewhere to refer to, like a CoG as you say and I agree with all that.

However as blueloo pointed out:

“For IFR, by day /night within 30nm of the Aerodrome

Tracking, by day within 5nm of the Aerodrome

or night within the circling area or within 5nm (7nm ILS) of the aerodrome aligned with RWY C/L etc , or within 10nm (14nm RWY 16L/34L) of the Aerodrome etc...?”


Now all that I am suggesting is that documents like the AIP are often written in lawyer speak. So let’s take the example of ‘tracking, by day within 5nm of the Aerodrome.’
I then take this to really read in lawyer terms (referring to the definition of an aerodrome in the AIP):
“tracking, by day within 5nm of a defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft.” i.e. the aerodrome.

And the same goes for the other examples. So that then means that you would be correct to use the VOR or threshold for reference as these are “buildings, installations or equipment intended to be used either wholly or in part for the departure movement of aircraft”. The ARP should be ok as well as this should lie somewhere within all these points. However I don’t think you need to use the ARP for reference to the 5nm (or 30nm or whatever else) within the aerodrome as stated above because if the AIP had wanted you to use the ARP it would have said “Tracking, by day within 5nm of the ARP,” and as you pointed out, there is a definition of the ARP so it would also assume you know what that is and not expand on term ARP as it does not expand on the term “aerodrome”.


John,
I’ll admit that having never used GPS as a primary means of navigation, I missed using the ARP for the IFR GPS if that is what you do.

However, what I was getting at with my comment you quoted is that most approaches in Australia in aircraft, pre GPS and in some cases even post GPS, would use the DME from the VOR to find out their distance from the aerodrome. As all CTA steps in Oz (except of course for Brisbane which changes for some unknown reason halfway in and goes to the ARP:confused: :confused: ) are based on the primary airports primary navaid (usually the VORDME,) then depending on your operation I think that it would be timely to have a reference to that instead of the ARP, having agreed up above that they are both part of the aerodrome:D. Also the MSA is also usually referenced to this navaid as well.
Now I am not criticising you for your operation using the ARP with the IFR GPS set up as I am not endorsed for GPS approaches or the use of GPS so do not know enough about it to comment. I am just thinking of the references I use when going to an airport in an aircraft that is without GPS, even though it does have an FMC on which I can display the ARP as I so desire.


Here is another little funny tricky one for you operators of CAT D aircraft. At night for a visual approach there is a requirement to be within 5nm of the aerodrome, on runway centerline, not below slope etc but by that stage you will already be within the circling area of 5.28nm anyway……………..

Cheers and beers.

[John Citizen]

Lets look at the definiton of aerodrome again :

Aerodrome = area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft

You then say :

So that then means that you would be correct to use the VOR for reference

I disagree with you here, even though the VOR is an "installation used during arrival/departure."

Take a careful look at some approach charts and you will see that a VOR is sometimes outside the aerodrome boundary/perimeter !!

Therefore I believe just because you are within 5nm/30nm..(the required distance) of the VOR, you are NOT necessarily within the 5nm/30nm...(the required distance) of the aerodrome.

Take a look at some of these examples :

The Cairns VOR is 2.2nm from the ARP. By reference to the Cairns noise abatement chart, it is obvious the VOR is not situated at the aerodrome. It is situated acoss the road (some road) from the airport towards Holloways Beach area.

Lets say you are approaching Cairns from the North. If you make a visual approach within 30 DME Cairns, you are NOT within 30nm of the aerodrome, but still at 32nm from the Aerodrome.

If you are approaching from the south, 30 DME Cairns will actually put you at 28 nm from the aerodrome.

I believe that is why they publish an ARP, as its the geograpic location of the aerodrome (as the definition says). By reference to an aerodrome chart, you can see the ARP is normally right in the middle of an aerodrome (not several miles away as a VOR/DME can sometimes be).

Take a look at the Cairns aerdrome chart and you won't see the VOR/DME marked anywhere because it is not there anywhere on the airport or within its boundaries.

Now take a look at Canberra. The VOR is 1.3nm from the ARP. Once again by reference aerodrome chart, it is obvious the VOR is not situated at the aerodrome as it is not shown anywhere.

Now take a look at Alice Springs. The VOR is 1.5nm from the ARP.
By reference to the aerodrome chart, the VOR is shown to be on the other side of some road (highway) from the airport. Once again, outside the aerodrome boundary.

But you might say, take a look at the definition of aerdome and read it carefully. It says "installation for departure/arrival !".

However, isn't a marker beacon also such an installation ?
How about a locator beacon for the ILS which may be up to 10 miles away from the ARP !!

Does this now mean the aerodrome area/boundary includes up to and including any marker beacons, locator beacons which may be up to 10 nm away from the ARP ?

Does this now mean we can do a visual approach 40nm from the ARP because we are within 30nm of an aerodrome arrival installation ?

I do not think so.

I believe that is why the ARP exists, is published and why it is part of the GPS/FMC database.

What else would it be used for ?

You wrote :if the AIP had wanted you to use the ARP it would have said “Tracking, by day within 5nm of the ARP,”

But the AIP also does not say VOR/DME. It just says "aerodrome".

Aerodrome = area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft

Lets forget about nav-aids and now assume aerodrome is now all the buildings, terminals, hangar, runways, taxiways, which is usually enclosed by some type of cyclone fence along the boundary.

Now lets say that as long as we are within this boundary (within the cyclone fenced off area) we are within the area of the aerodrome.

Therefore when determining our distance from the aerodrome, we are now talking about our distance to this boundary (cyclone fence).

If that is the case, then how come this aerodrome boundary is not published anywhere ?

Why isn\'t the aerodome physical boundary contained within the GPS/FMC database ?

I\'ve looked through my approach charts and I can not not see a published boundary anywhere.

Once again, as I said, that is why I believe they publish an ARP and not an aerodrome physical boundary map (cyclone fence map).

Thats why I believe all distances to an aerodrome will be relative to the ARP and not to any nav-aid, terminal or surrounding cyclone fence.

Now I might be all completely wrong here, but let me go back to the first post and answer the question.

I know that if I am within the required distance of the ARP, I know that I am definitely within the required distance to the aerodrome / aerodrome boundary (ie. the area that includes buildings, any nav-aids on the aerodrome, etc..and don't forget the cyclone fence).

[amos2]

Now look!...anybody with half a brain knows that the ARP is the answer!

So, can we drop this now? Before we start to think you modern day turkeys are serious? ;)

[blueloo]

amos2, you may be correct. Would you mind showing me the reference which says that.

[John Citizen]

Obviously you are one of those of people with less than half a brain. :uhoh:

How many times do I have to :mad: repeat myself.

Just think about it :

Aerodrome reference point = this means we refer to this point for the location of the aerodrome

Do you understand English ?

Aerodrome reference point :
- is published on all approach charts
- is contained in all GPS/FMC databases
- is the published location (lat/long) of the aerodrome

The VOR/DME IS NOT always positioned within the physical boundary of the aerodrome so to use the VOR/DME as a reference point can not be 100% correct all times. Though I agree that the VOR/DME is good enough in most situations as it is usually situated on the aerodrome somewhere not too far from the ARP.

However what if there is no nav aid at all ?
Like you are flying to a no aid aerodrome during the day and you want to know when you are within 30nm for a visual approach ?

The only reference you can use now is the ARP and nothing else.

It is the only aerodrome waypoint you can select on a GPS for a no nav aid aerodrome (disregard any GPS NPA waypoints).

I am well aware an aerodrome is more than 1 specific point on the ground and that it includes the surrounding buildings/runways/taxiways. However how can we use the physical boundary that surrounds an aerodrome as a reference if it is not published anywhere on any type of approach chart nor contained in any GPS data base ?

But you say it is not written anywhere.

Does it have to be specifically written ?

Don't you know how to read English and infer ?

It doesn't specifically say on someone's head that they are a
:mad: but once again, it is not too hard to work out sometimes :p

[blueloo]

I may indeed have half a brain, in fact probably only a quarter, but nevertheless, this whole thing started out as a reasonably simple question, yet, there is significant debate as to the correct answer.

I dont know what the correct answer is. Whilst common sense says the ARP is fine and I am sure it is, I still have not been convinced that it is the 'correct' answer - thats if we get into the actual wording of definitions. I dont even believe using the ARP is practical either. Sitting there getting cleared at the last minute to do a visual approach, and having to pull out the pen and measure the jepps chart in a time limited/busy environment is not terribly smart. In practicality, I would be saying bugger off to the ARP, and essentially using the VOR/DME - and if needing the extra little bit of distance use distance from threshold.


In a small jet, or bug smasher, the distances are not so constraining. In something a little larger, depending on the approach, CTA steps, etc it can be a little more constraining. If you use the ARP, and the ARP is at the other end of the Aerodrome, or 2000m from the threshold, you have lost a fair bit of distance to play with.



Maybe there is no answer.

[Icarus2001]

blueloo No there is an answer and John Citizen has explained it pretty well. Not everthing is written, sometimes we have to extrapolate and interpret what is written to find a meaningful answer.

this whole thing started out as a reasonably simple question, yet, there is significant debate as to the correct answer. True. However how many of the participants in the discussion are either professional pilots or private pilots who fly IFR regularly, say 3-4 times a week? Everyone has an opinion but some should be given more weight than others. The strength of this forum is also it's weakness.
:ok:

Now go flying for goodness sake.

[John Citizen]

you say :

Sitting there getting cleared at the last minute to do a visual approach, and having to pull out the pen and measure the jepps chart in a time limited/busy environment is not terribly smart. In practicality, I would be saying bugger off to the ARP,

It is not as difficult to use the ARP as you think it is.

If you are flying to a no nav aid aerodrome, then the GPS would be set up to the ARP anyway (as there's no other waypoint you can choose for the aerodrome).

So no need to pull out pen and measure anything here, just look at the GPS !!

If you are tracking to a VOR/DME and you have a GPS, all you have to do is select the ARP on the GPS. This can all be done very easily within 30 seconds, if not quicker (just push a few buttons on the GPS).

If you are in a multi crew environment, then this not difficult at all. One pilot continues to fly the plane as the other pilot setups the GPS. Nothing terribly stupid here.

Once again, not difficult at all, and definitely no need to pull out a pen and measure any chart.

You say
I dont even believe using the ARP is practical either

I find using the ARP very practical, as I use it all the time, and nothing too difficult or impractical about it at all.

[hoss]

Had a bit of a laugh last night going into Ballina. Looked at the Jeppesen 16-1 on the aerodrome chart and it does not show an ARP:ouch:

Love learning stuff at PPRuNe School.

;) hoss

[John Citizen]

You say :

In a small jet, or bug smasher, the distances are not so constraining. In something a little larger, depending on the approach, CTA steps, etc it can be a little more constraining. If you use the ARP, and the ARP is at the other end of the Aerodrome, or 2000m from the threshold,

To start with, if you study your aerodrome charts carefully, you will see that the ARP is not normally at the other end of the aerodrome (opposite side to any threshold) but is normally right in the dead centre/middle of the entire aerodrome area.

Like if you take a careful look at an aerodrome chart, for aerodromes with 1 runway, the ARP is positioned in the middle of the runway (length wise).

For aerodromes with several runways, the ARP looks like it is positioned in the average mid-point of all the runways.

Just take a look at some examples yourself.

You then say :

you have lost a fair bit of distance to play with.

Is this when comparing using the VOR/DME versus the ARP ?
You are both right and wrong here, depending where the VOR/DME is relative to the ARP.

Take a look at Cairns where the VOR/DME is 2.2nm (about North) from the ARP.

If you are approaching from the North, then you will gain this extra 2.2nm by using the VOR/DME
but if you are approaching from the south, you will lose 2.2nm compared to using the ARP.

So your belief that the distances be a little more constraining. If you use the ARP, and the ARP is at the other end of the Aerodrome, or 2000m from the threshold, you have lost a fair bit of distance to play with also applies to when using a VOR/DME which is positioned on the other side of the aerodrome, or even 2nm away from the aerodrome on the other side.

By using the ARP. you know this point is in the average middle of the aerodrome (average for all runways, and not on the opposite side) whereas a VOR/DME could restrain you even more (lose distance to play with) if it is on the opposite side and maybe several miles away !!

Some example where the VOR/DME would constrain you more than the ARP are :
- Cairns Runway 33, Runway 30
- Canberra Runway 35, Runway 30
- Darwin Runway 11
- Brisbane Runway 01
- Alice Springs Runway 30

Do I need to find any more examples ?

[regitaekilthgiwt]

Okay…

John:
You say that you disagree with me when I say that you would be correct to use the VOR for a reference, even though you admit “the VOR is an “installation used during arrival/departure.”

Now lets again go back to the AIP definition of an aerodrome:
"Aerodrome: A defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft."

thus, if the VOR is an installation used during the arrival/departure procedure, then it can be considered usable to define a distance from the aerodrome (using the DME). So by you disagreeing you are saying something contrary to the AIP. As you say, there are some places where the VORDME is a distance from the ARP, however, just because it is a distance from the ARP doesn’t mean it is an unsafe distance from the runway itself and hence why it is applicable to be included in the definition which defines the area of the aerodrome. One of the example you use is Cairns. Sure by reference to the noise abatement chart the VORDME is 2.2nm from the ARP, however if you refer to the ILSDME for runway 15 you will see the VORDME is actually only situated 1.1nm from the threshold of 15. To go further to your examples of cyclone fences, I must confess that I do not know much about such fences, however I would imagine at some airports there would be parts where the “cyclone fence”, building or other installation which defined an aerodrome are further than 1.1nm from the runway (which after all is where we are landing and is obviously a “installation used either wholly or in part for the arrival, departure and movement of aircraft”). I see you have also kindly referred me to Canberra, may I do the same and refer you to the VORDME for runway 17 and we can see that in this case the VORDME is even closer, only 0.6nm from the threshold, the same argument as above applies. Darwin, within a mile of the 29 threshold, Brisbane right up there too, etc. I suppose if you wanted to be really really picky you could add/subtract this short distance from the VORDME to the threshold (doesn’t matter what end, its all the runway) and figure out your exact distance from the runway. But remember that we doing a VISUAL APPROACH and as a result there is no requirement to be reference anything except the aerodrome which, by the definition the VORDME among other things is a part of.

Now please, a locator beacon for the ILS? The locator beacon/outer marker is for use with the ILS which is located very, very near the runway which of course is undoubtedly part of the aerodrome. So please don’t get carried away, and if you are going to go and say, ok then what about the locators used in the TWIN LOC approach into MEL or AV or some such place, well 1. You would only realistically be doing it if required in IMC so all bets are off for a visual approach, and 2. the MEL approach is a TWIN LOC DME, so you already have reference to the DME and at Avalon, the AV locator is 0.6nm from the threshold anyhow so the previous argument applies, however I think it is a pointless argument for the TWIN LOC as it would be an IMC/simulated IMC maneuver anyhow.

Q. “Why isn’t the physical boundary contained within the GPS/FMC database.”
A. “Because it doesn’t need to be.”

The ARP is not published just for the purpose of making a visual approach. Think about it logically, if it was I can’t imagine they would have necessarily called it the ARP and in the rules for making a visual approach I would have thought they would have referred you to this point and not the aerodrome and the associated definition. However I will stop speculating and stay with the facts.
I am not saying you are incorrect in using the ARP for reference for a visual approach. It is part of the definition of an aerodrome and you can use this. However, what if for some reason you cannot find one, such as in hoss’s case. You need to have other alternatives, especially if you are not equipped with a GPS/FMC and only a DME.

Now onto the latter posts, I don’t think blueloo is someone with less than half a brain, I think he/she is someone who is thinking more laterally than most on this topic.
Going to an aerodrome with no nav aid at all? What’s wrong with using the runway threshold as you can load in the FMC, which is less limiting that the ARP? Not everyone is restricted to the ARP in the GPS.

Q. Does it have to be specifically written?
A. Yes it does. As it is not specifically written as the ARP, ARP does not specifically apply. It is however specifically written as a defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft. (Providing that was the “it” you were referring to).

Blueloo is spot on with the fact that the ARP can be impractical. Being cleared to do a last minute visual approach, going head down to enter to ARP for even period short of 30’ is not good airmanship, especially if there is a quicker and more legal way to do it. i.e. look at your distance to run from the VOR/DME or look at the distance to run to the threshold if the FMC is configured correctly. Even in a multi crew environment, one pilot going head down late in an approach to make corrections in the FMC/GPS when not absolutely necessary is not an ideal situation. Also when doing an approach where the distance is constraining, if there is legally another way to do it (apart from the ARP) then using this less constraining point to have a less steep and more stable approach is the smart thing to do.

Icarus2001. Almost everywhere everything IS written and we do have to correctly interpret the rules to find the CORRECT answer to operate safely and legally.

In the cases you mentioned in your last post, John, I think the examples you give are again a timely reminder of the distances from ARP to the VOR and the problem with using the ARP as the primary reference point for the approach as the ARP can be quite a distance from reference point of the VOR used for most CTA steps and of course, the MSA.
As for the examples you raise of the VOR being more limiting, it is only more limiting if:
1. You don’t use the distance from the threshold as displayed in the FMC (or the co located DME associated with the ILS to the runway your are landing on) and then perhaps cross check this with the expected additional miles from the VORDME (when using the FMC); or
2. You don’t do enough forward planning to figure out the distance of the VOR to the threshold, or the fence of whatever else for your landing runway and then add the correction. I only say threshold as it is the obvious one because as you say, there is no point as to where the fence is it, however you can use the distance of the VORDME to the threshold on the reciprocal runway chart then add the length of the runway to determine how far from the VORDME your landing threshold is (as done for a circling approach).

I hope this helps clear up the points that, although the ARP is one correct way of doing it, there are other correct ways of determining your distance to run to an aerodrome to commence a visual approach and even when the VORDME is not right next to the ARP, it can still legally be used as an aid to judge your distance.

[swh]

hoss,

My BNA 16-1 does not show a little ARP symbol, but does state the ARP as S28 50.0 E153 33.7 in the top RH corner

The diff between the ARP and NDB posn (S28 50.1 E153 33.7) at BNA (.1 of a minute) is so small its not funny.

blueloo,

As for your questions...I think they have been asked of you to promote discussion, there is no one correct answer...

My explanation is as follows :

By Day or Night you can use the 25 and 10nm MSA, the MSA invariably is based upon the most accurate aid at the aerodrome, if operating to an aerodrome with only a GPS approach, this will normally be based upon the ARP.

By similar means LSALT is mentioned, LSALT invariably is taken from the most accurate aid at the aerodrome and the distance and bearing (used to calculate the splay for LSALT terrain clearance is based upon the aid) is then calculated from this point, not the ARP, except of course where there is no aid.

By day or night "the MDA to the procedure being flown", so that comes back to the airport your operating into, the runways it has, etc, eg if you were doing a VOR/DME 16R and circle north of RW 25 for RW 25 you need to take into consideration not only the circling area for the threshold of RW 25 for your CAT of A/C, but also the 3 DME SY limit.

RW 16L and 34R at SYD do not have an ILS installed, they are ILS DME approaches, my belief for these approaches is that the 14 nm should be taken from the ILS DME, the 10 nm for places like 01 BNE are marked on the chart as D10.0 BN VOR. Similar with CNS, its marked as D10.0 CS for the ILS.

New charts use the runway thresholds, older charts will use 3nm of the ARP if less than 1800 m, and 3nm arcs drawn from the thresholds.

I think the question asked is fair, has promoted discussion, and made you think.

[amos2]

I think I might become a brain surgeon!

This flying game is getting to complicated for me! :{

[hoss]

No worries swh mate:ok: . I was just trying to stir things up a bit:) .

[John Citizen]

You say : (all in blue)

John: You say that you disagree with me when I say that you would be correct to use the VOR for a reference, even though you admit "the VOR is an "installation used during arrival/departure."

Read what I said carefully, I do not entirely disagree with you.
I agree it is OK to use the VOR as a reference BUT ONLY when it is actually situated on the aerodrome.
I agree the VOR is an installation during arrival/departure however I do not agree it is part of an aerodrome when it is not actually physically located on the aerodrome or within the boundary (eg. Cairns). Therefore, in such a situation, only then I believe it is not the correct reference waypoint to determine distance from aerodrome, as it is not located on the aerodrome.

Now lets again go back to the AIP definition of an aerodrome:"Aerodrome: A defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft."

Let me explain again..........
But you might say, take a look at the definition of aerodrome and read it carefully. It says "installation for departure/arrival !".

However, isn't a marker beacon also such an installation ?
How about a locator beacon for the ILS which may be up to 10 miles away from the ARP !!

Lets look at the Perth ILS for example, Runway 24 ILS. You will see that the Outer Marker is 5.3 at dme and that the locator beacon (PRL) at the commencement of the approach is at 9.6 dme.

Does this now mean the aerodrome area/boundary includes up to and including any marker beacons, locator beacons which may be up to 10 nm away from the ARP ?

Does this now mean we can do a visual approach 40nm from the ARP because we are within 30nm of an aerodrome arrival installation ?

I do not think so.
What I am saying is that if the “installation” is not on the aerodrome, then I don’t believe it can be used as a reference point.


thus, if the VOR is an installation used during the arrival/departure procedure, then it can be considered usable to define a distance from the aerodrome (using the DME). So by you disagreeing you are saying something contrary to the AIP.

I am not disagreeing or contravening the AIP at all here. Where does it specifically say this in the AIP that the VOR can be used as an aerodrome reference point when making a visual approach ? Where does it specifically say the VOR is part of an aerodrome. You are the one making your own rules and definitions here by calling the VOR part of an aerodrome when “sometimes” IT IS NOT.

If VOR is part of an aerodrome (your belief), then so is a Locator beacon which is 10 miles away !! So if I go by what you say, I can now do a visual approach from 40nm because we are within 30nm of an arrival installation.

You are the one making your own rules/definitions and procedures by defining a VOR situated “off the aerodrome” (eg Cairns) as being part of the aerodrome when is not.


One of the example you use is Cairns. Sure by reference to the noise abatement chart the VORDME is 2.2nm from the ARP, however if you refer to the ILSDME for runway 15 you will see the VORDME is actually only situated 1.1nm from the threshold of 15

Now what has distance to threshold got to do with it ?
Didn’t the AIP say “distance from aerodrome” and not threshold ?
Mind you, when is the threshold distance used for the arrival ? lol
I am glad you wrote yourself the fact that the VOR/DME is 1.1nm from threshold at Cairns.

So even now you can see that 30 dme does NOT put us within 30nm of aerodrome, or even threshold (your own rules)
So at 30dme you will be 31.1 dme from threshold or 32.2 nm from ARP !!!!!!!!!!
Are we within 30nm of the aerodrome (or even the threshold) at 30 dme ? NO WE ARE NOT

So dont try and tell me the VOR is a legal reference point when IT IS NOT.
IT WILL NOT PUT YOU WITHIN THE REQUIRED DISTANCE (30/10/7/5nm) FROM AN AERODROME
Then how can you now say we can use the VOR/DME when it actually put us “short” of both the threshold and ARP ???
You making your own rules again I see
And you would now be the one who was contravening the AIP if you made a visual approach at 30 DME to the North of Cairns because you would not be WITHIN 30NM OF THE AERODROME !!
Or not even within 30nm of the threshold !!!!!!!!!
As you said yourself, the threshold is another 1.1 nm further away !!!!!!!!



I see you have also kindly referred me to Canberra, may I do the same and refer you to the VORDME for runway 17 and we can see that in this case the VORDME is even closer, only 0.6nm from the threshold,

Yes, true, you are right, its closer to the threshold, but on the other side of the threshold. But why do you now raise the threshold in this discussion ? Where does the AIP specifically say “reference to distance from threshold”. You always tell me it doesn’t specifically say ARP, well I am telling you it doesn’t specifically say “threshold”you hypocrite.
I agree the threshold is a part of an aerodrome, however nowhere does the AIP say we can use it. The AIP specifically says distance from aerodrome and not distance from parts of what makes up the aerodrome. The AIP does not specifically anywhere say distance from threshold.
And the most important thing about it, this means if you are at 30/10/7/5 dme, you will NOT be within the required distance (30/10/7/5 nm) to the aerodrome (ARP) as the DME is NOT SITUATED ON THE AERODROME


a locator beacon for the ILS? The locator beacon/outer marker is for use with the ILS which is located very, very near the runway which of course is undoubtedly part of the aerodrome.

NO IT IS NOT very very near. You got no idea. are you telling me that a marker beacon (outer marker beacon – perhaps 5 miles away) or locator beacon (maybe 10 miles away) is very very near ????
Lets look at the Perth ILS again, Runway 24 ILS. You will see that the Outer Marker is 5.3 at dme and that the locator beacon (PRL) at the commencement of the approach is at 9.6 dme. Now don’t try and tell me that 10nm is very very near the runway ? 10nm literally is miles away from the aerodrome.
NOW YOU PLEASE Don’t you get carried away here. You are completely wrong.

Going to an aerodrome with no nav aid at all? What's wrong with using the runway threshold as you can load in the FMC,

Because where does it say this is legal ? Where does it say you can do this ???? Whats wrong with loading the ARP instead ? The ARP will give to the distance to the aerodrome from any direction for any runway, but the distance to the threshold is limited to only one runway.
By the way, the majority of aircraft these days don’t have FMC. I am speaking for the majority of pilots here, so lets forget the FMC/threshold distance all together. In that case we are only limited to nav aids and a GPS. A GPS with the ARP in its database is far more common in aircraft these days compared to a FMC with threshold waypoints

Q. Does it have to be specifically written?
A. Yes it does. As it is not specifically written as the ARP, ARP does not specifically apply

Then in that case, distance to threshold does not apply, as threshold is also neither specifically written anywhere. You are nothing but a hypocrite.

Blueloo is spot on with the fact that the ARP can be impractical.

No he is not, let me repeat myself, I use it all the time and I find it very very practical. I say again “I use the ARP all the time and find it very practical”
Like with no nav aids at the destination and no FMC (vast majority of us), what other choice have we got but to use the ARP ?

Being cleared to do a last minute visual approach, going head down to enter to ARP for even period short of 30' is not good airmanship, especially if there is a quicker and more legal way to do it. i.e. look at your distance to run from the VOR/DME or look at the distance to run to the threshold if the FMC is configured correctly. Even in a multi crew environment, one pilot going head down late in an approach to make corrections in the FMC/GPS when not absolutely necessary is not an ideal situation

If you can configure the FMC to read your distance to threshold, then you can just as easily also configure the FMC/GPS distance to ARP !!!!!!
But don’t you require heads down to configure the FMC to threshold ? Didn’t you tell me heads down is not good airmanship ??
So isn’t it now not good airmanship to configure the FMC to threshold distance now ?????
You are just contradicting yourself here you hypocrite.
Like you tell me its ok to load/configure the threshold into the FMC but all off sudden its terribly stupid and dangerous to load the ARP into the FMC/GPS
I say if you can load the threshold into the FMC, you can just as easily load the ARP into the FMC/GPS.

As all CTA steps in Oz (except of course for Brisbane which changes for some unknown reason halfway in and goes to the ARP ) are based on the primary airports primary navaid (usually the VORDME,) then depending on your operation I think that it would be timely to have a reference to that instead of the ARP

Take another look at your steps again. You will see that the inner most step (CTR boundary) is usually based upon the ARP and not DME. I just looked them up in the DAH, and out of 14 CTR boundaries, 12 were based on ARP, and only 2 civilian aerodromes in the whole of Australia are based on the DME !!
Therefore, I think that it will be timely to have a reference to the ARP and not the DME.

[swh]

John,

I dont agree with you....

When you are cleared for a visual approach such as PH RW 24 your clearance would be ..

"Once established on the ILS from 10 nm make visual approach"

When they say "from 10 nm make visual approach" its either DME or ILS/DME. If you are using GPS in lieu on DME, the chart that you are using will specify the waypoint for distance from the aerodrome, this maybe the ARP, DME, VOR, or NBD.

My understanding for this 10 nm is that the glidepath coverage is ±8º azimuth coverage at 10 nm. Maybe OzExpat can clarify this.

If your using a GPS for distance, what procedure do you use to ensure they have the required accurancy, i.e. do you do a RAIM prediction when asked to make a visual approach, and do you have the GPS notams ?

:hmm:

[cogwheel]

swh said:
"Once established on the ILS from 10 nm make visual approach"

Of course you would not read that back would you? (just one out of left field) And I vote for the ARP.

[swh]

cogwheel,

My apologies...you are correct..should be "WHEN established .....CLEARED visual approach"

:oh:

[John Citizen]

you say established at 10nm, but from what reference ?
(a)- VOR/DME
(b) - any locator/marker beacon or any other "installation used during arrival"
(c) - missed approach point
(d) - threshold
(e) - aerodrome (ARP)

Now lets look it up.

AIP ENR 1.5 1.14 (http://www.airservicesaustralia.com/pilotcentre/aip2/aip/enr/15739.pdf) says :
the aircraft is established within 10nm of that aerodrome...

I interpret the aerodrome as being the ARP !!

It is does NOT specifically say threshold or VOR/DME.

[swh]

John,

This topic is discussing the "need not to continue or may discontinue the approved instrument approach to that aerodrome "...i.e. Visual Approach.

Continue to look at the night case, the first 4 conditions and tell me where it mentions "aerodrome" when you consider a descent within the circling area.

As for the ILS case, or ILS DME case, any reasonable person would agree that and ILS or ILS DME is "installation and equipment intended to be used either wholly or in part for the arrival of aircraft" and the Runway which the ILS or ILS DME also fits nicely under that aerodrome definition.

Now going back to your PH 24 ILS example, and have a look at the "USE OF NAVIGATION AIDS" paragraph in the AIP ... "Use of a non-specified aid (e.g. another DME located on the aerodrome) is prohibited as it may jeopardize the integrity of the instrument approach procedure."

The way I read that, if your using the 24 ILS for a "Visual Approach" you must use the aids on that chart, not the ARP.

I would be interested to hear of your views on this.

:ok:

[hoss]

swh, found another one;) . Seems Albury is missing an ARP symbol(jepp).

Anyone thought about the 14nm for 16L and 34L at Sydney Intl, why? :ok:

:)

[John Citizen]

Take a look at some Airservices documents instead (ERSA/DAPs).

You will see that the ARP is shown for both Albury and Ballina.



swh

Since when was the ARP a nav aid ?

Nav aids required for an approach and instrument approaches are not always relevant.

For example, you might be in day/night VMC and at some stage you will have to leave your LSALT/MSA. This does not always require an instrument approach !!

From my observations, visual approaches are far more common than instrument approaches.

[Capt Fathom]

Anyone thought about the 14nm for 16L and 34L at Sydney Intl, why?Maybe because the ILS Approach commences at 4000' for those runways. When INDEPENDENT VISUAL APPRS are in operation, you can then be cleared for a visual approach from 4000' and 14nm. If you need to fly the ILS, I gather it stuffs up the flow.
This is just a guess mind you.

[downwind]

Because the parallel runway thresholds at Sydney are displaced and to enable the conduct of independent visual approaches to those parallel runways, approval was granted for the use of visual approach from the increased distance from the further threshold (34L and 16L).
:O

[regitaekilthgiwt]

John,

As you said in your previous posts, where does the aerodrome boundary start and end? Earlier you talked about cyclone fences and the like? How do you know that just because the VOR isn’t within the intersecting of the runways and is a small distance from the threshold that it isn’t at the aerodrome...

Now, you are asking me to read what you said carefully, please return me the same courtesy. I have never once said that it is ok to use any locators for use with an ILS as a reference for the aerodrome. What I said was:
“The locator beacon/outer marker is for use with the ILS which is located very, very near the runway which of course is undoubtedly part of the aerodrome.”
Now let me explain exactly what I meant a little more clearly. The LOCATOR BEACON/OM is for use with the ILS, i.e. it wouldn’t be there if there was no ILS as you wouldn’t require a check height. Therefore what I meant but might not have said clearly enough for you is that as the locator/OM is for use with the ILS, therefore your reference is the ILS (i.e. the ILS INSTALLATION located at two points very, very near the runway). Please don’t sit here and proceed to tell me I have not idea. I have not once said such a thing to you even though I don’t totally agree with your pov. Play the issue not the man.

I don’t believe I am making up my own rules and definitions any more than you are. You ask where does it specifically say in the AIP that the VOR can be used as a reference point for making a visual approach, my answer is it specifically states it in the definition if it is going to be an installation/equipment intended to be used for part of the arrival. Now I ask you where does it SPECIFICALLY say in the AIP that the ARP must be the point of reference for the aerodrome when making a visual approach? Well of course it doesn’t either, does it?

To quote you again:
“Now what has distance to threshold got to do with it ?
Didn’t the AIP say “distance from aerodrome” and not threshold ?
Mind you, when is the threshold distance used for the arrival ? lol”
I hope you were joking. What has threshold got to do with it? Whilst I acknowledge the only requirement to use the threshold as a distance in the AIP is for the calculation of circling areas, why can’t it be used in the instance of a visual approach. Yes the AIP said distance from the aerodrome, which mean in other words (sorry I am getting sick of writing this): Distance from the defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft.
Now if you are going to sit here and tell me that the RUNWAY is not an INSTALLATION that is going to be used for the ARRIVAL of your aircraft then I give up.
As the runway is part of the aerodrome then so is the threshold, so distance from the threshold is quite ok to use and therein lies your answer to the question of when is the threshold ok as per the AIP.
Now again if you are worried about the VOR being outside the aerodrome, which even if it is 1.1nm away from the threshold (you are yet to have given me a reason to say that is outside aerodrome “boundary”), then add that 1.1nm correction to your distance to run to the VOR and you will have a distance from the threshold, it doesn’t matter which end of the runway you are on, the threshold is going to be on the runway be it whatever end of the runway and the runway must be an installation/building/equipment on the aerodrome. Or if you decide that the distance from the VOR is from the runway is still within the aerodrome boundary or “cyclone fence”, then just use the VOR. Either way, as long as you have done some planning, the VOR is FINE to use as a reference for the approach.

I think I have covered why it is legal to use the threshold as a reference to the aerodrome. You ask what’s wrong with loading the ARP, probably nothing, except it is slightly more limiting. You say the majority of aircraft these days don’t have an FMC but have GPS, fine if that’s your opinion, but as to “so lets forget the FMC/threshold distance all together”, well lets not, they are applicable. If you only have the GPS, well fine, put in the ARP but as I am saying with the VOR if desired or required, put in a distance correction from the ARP to the threshold or fence or whatever to give yourself more distance. Again, as I am continually saying, the ARP is not incorrect but it is not the only answer. Going back to the FMC/threshold distance, I will quickly explain how the FMC works for this. After programming an approach to the runway, the FMC will display your distance to run to the threshold. In a typical situation this will usually be displayed before top of descent, well before 14/10/7/5nm to run to the runway. So there is NO need to go and reconfigure anything on final approach and thus NO need to be heads down. If you are cut in by ATC inside what is programmed, if anything the distance is going to be limiting, i.e. the FMC showing more track miles to run. So I am not being a hypocrite, please get your facts straight before you go accusing me of being one.

As to the reference to CTA steps, haven’t got the charts in front of me but from memory I disagree that 14 of oz’s aerodrome CTA steps are wholly reference to the ARP, and the MSA’s defiantly aren’t.

John you say to swh, and again seem to miss the point, that to quote AIP ENR 1.5 1.14: “the aircraft is established within 10nm of that aerodrome...” implies:
within 10 nm of that defined area of land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure and movement of aircraft.
While it doesn’t SPECIFICALLY say threshold or VOR/DME it doesn’t specifically say ARP. So it is open to interpretation and I think I have explained that whilst it doesn’t specifically say threshold, the threshold must be part of the aerodrome...
You put option (e): “– aerodrome (ARP)” - that is crap because whilst the ARP is pat of the aerodrome, the aerodrome is not only the ARP.

You then in the next post say “since when was the ARP a nav aid?”. Isn’t that exactly what you are arguing to use it for? - An aid to navigate distance from the aerodrome. Whist it is not a physical installation, building or piece of equipment like VOR etc, I understand you to be still using it as a nav aid?

I think at the end of the day what I said above is the best answer to the notion that the reference must be the ARP:

ARP is part of the aerodrome, the aerodrome is not only the ARP.

[John Citizen]

Take a look in the DAH (http://www.airservicesaustralia.com/pilotcentre/aip/dah/2ctrc.pdf)

This is where I found the information (online).

I also have not got the charts in front of me.

Yes, I was slighty wrong, I did not include Class D CTR's. I now include both Class C and D :

The following CTR boundaries are based on ARP (16) :
- Adelaide
- Albury
- Alice Springs
- Amberley
- Avalon
- Canberra
- Darwin
- East Sale
- Edinburgh
- Hobart
- Launceston
- Melbourne
- Scherger
- Tindal
- Townsville
- Woomera

The CTR boundaries based on the VOR/DME are (11) :
- Coffs Harbour
- Curtin
- Gold Coast
- Hamilton Island
- Learmonth
- Mackay
- Maroochydore
- Oakey
- Perth
- Rockhamptom
- Tamworth

From the above you should be able to conclude that the CTR boundary is more often based on the ARP than VOR/DME.

[Capt Fathom]

When a controller says 'call at ten miles', where does he want you to call?
IT DOESN'T MATTER!
As long as it's ten miles! I don't measure it in millimeters. I look at the chart, I look at the golfcourse, I just look at the airport and think..yep, that's ten miles!!!!

[amos2]

...except, he will say, " Report at 10 DME "

[regitaekilthgiwt]

I have been away so it has taken me a while to reply.

John,
I never disputed that the boundary of CTR is based on the ARP. If you actually read what I wrote you will see that I wrote CTA, which, I believe is more limiting when flying to, or in the vicinity of, an aerodrome with class C airspace. You will see that class C CTA airspace is based on the VORDME and not the ARP. The only exception I have come across being that the BN CTA steps become based on the ARP at 15nm, ie YBBN, but then from 7nm the step is based on the THRESHOLD. Cairns has a similar setup with the threshold. There may be others, the Gold Coast steps are based on CG DME until at least 15nm, Maroochydore on the MC DME until 8 miles, I can go on. At the end of the day if you are flying around a major aerodrome you will need to reference yourself to the VORDME for that airport for the CTA steps, and if you are flying into the aerodrome, as long as you are flying a normal 3 degree path, CTA LL will more often than not be more limiting than CTR. Also again, defiantly more important than any of this is that the MSA and this is referenced to the VORDME.

Further to this debate. Can I please draw your attention to the PEPPA TWO ARRIVAL into Perth. In particular it says: For Rwy 21, Visual Procedure, At SPUDO track 262 to PH 6 DME (4.9 NM from threshold) final. Now if you are going to do the visual procedure then you will get a visual approach. So this would help indicate that the threshold and the DME are good references for the ‘aerodrome’ in this situation, how about the others…


amos2
Spot on, Gen Chap 5, section 5.9.2