NAS 2C - Class D Airspace Changes
 

NAS 2C - Class D Airspace Changes

We note that one of the proposed changes in the next airspace change tranche – NAS 2C - is to amend Class D procedures. Our understanding from examining the NAS documentation is that this will involve a change in VFR entry procedures, so that simple acknowledgement of a call by VFR aircraft at the boundary may be taken as a clearance (implicit rather than explicit) to enter Class D airspace (on-line at the NAS website via Airservices Australia’s web-site).

We have reviewed your AIP (on-line at Airservices Australia) and note that the current procedures require VFR flights to obtain a positive clearance to enter Class D airspace.

We note that the NAS 2C changes will not amend airspace boundaries for Class D – i.e., VFR flights may enter Class D airspace at a boundary distance of more than 20 nautical miles. At that distance it would be impossible for air traffic control to positively sight and identify the aircraft concerned, and provide a meaningful service between IFR and VFR flights.

We have examined the United States procedures (AIM and ATC Documents (7110.65)) and note that Class D airspace in the United Stated most often extends to a maximum of 7 miles (typically 5 miles) and upper limits in the range of 2000 feet at each of the several hundred Class D towers (refer also FAA web-site at www.faa.gov). As is the case with aircraft entering your GAAP airspace (ref Australian AIP) it would definitely be possible for a controller to sight, identify, and provide services in respect of that aircraft, even with an implicit clearance.

This begs the question of the potential changes in risk that would be associated not only with the implementation (as has been claimed in respect of other changes) but also with the actual design itself.

We referred again to ICAO DOCUMENT 9689 - MANUAL ON AIRSPACE PLANNING METHODOLOGY FOR THE DETERMINATION OF SEPARATION MINIMA. That document contains an appendix submitted by Australia which outlines an airspace risk model for small terminal areas – CTAF and MBZ.

We understand that in 1996, attempts were made to change the Class C airspace associated with 12 regional non-radar towers to Class D airspace. We have been provided information that indicates that there was significant community opposition, and significant debate, which forced a review of that decision. A particularly detailed risk study was conducted, a 1997 copy of which was provided to one of our members.

The report of that study indicated that the change from Class C to Class D would increase risk in the order of ten-fold. In some cases, this brought the risk close to (but not above) the limits of tolerability – however Airservices Australia was able to implement the change to Class D in 1997.

The study built on the airspace risk model that had been presented to, and accepted by, ICAO. It is therefore reasonable to say that unlike the safety analysis associated with NAS, the modeling carried out on Class C and Class D airspace would genuinely fall within a statement that “it was based on ICAO guidance material”.

We have examined the model and find that it contains a number of fault tree decision points or failure modes, the likelihoods of which were determined from industry panel inputs.

It would therefore be relatively easy to re-assess the likelihood of certain events occurring if VFR aircraft were NOT subject to positive clearance – i.e., were potentially likely to enter controlled airspace by accident. A change in likelihood in just a few decision points can have dramatic effect on risk – to the point where the risk at a small number of the Class D towers would EXCEED the tolerable risk limits.

It should not require a great deal of effort on the part of Airservices Australia to re-model the proposed changes and provide a public risk statement.

We are not in a position to directly intervene here, but we believe that you should challenge your service provider both to re-release the risk analysis already done on Class D airspace – AND to carry out the re-analysis based on the changed procedure.

Should the Class D airspace limits be amended to those applicable in the United States, a commensurate increase or lowering of Class E airspace would be required (as applies in the United States). This would result in the potential for unannounced VFR flights to transit above Class D towers at 2500 feet.

In short, not only will the risk in residual Class D be raised, but the risk in the volume previously categorized as Class D - i.e., that airspace that becomes Class E - would increase even further than had it remained Class D with new procedures. The risk in Class E airspace between 2500 feet and 4500 feet can easily and validly be modeled within the model agreed by ICAO and referred to in the previous post (the Class D risk analysis conducted by Airservices Australia).

It is our considered judgment that without a commensurate change in the size of the Class D airspace to replicate the United States situation, the levels of risk to both IFR and VFR flights in Class D airspace would elevate significantly and may exceed already established risk tolerability limits, and in the risk workshops being conducted by your NAS teams, you must challenge them both to release that study, and commit to a re-calculation of design (and not implementation) risk.

Voices of Reason [[email protected]]

Voices

Some of what you refer to is already happening with the NAS 2b changes. You said, At Alice Springs, elevation 1780' AMSL, the Class D control zone is an irregular shape, with the upper limit being A045, conincident with the lower limit of Class E.

New procedures see IFR depatures instructed to call "Melbourne Centre airborne". So within a minute or so of being airborne, whilst trying to clean up the aircraft, one has to see and avoid and attempt to alert any unannounced VFR transit traffic, assuming they're on the same radio frequency, as there are three frequencies that could reasonably be deemed appropriate for a VFR flight (118.3 TWR, 119.8 Melb CNTR & 128.85 Melb CNTR), as well as call Melbourne Centre with departure details.

Whilst the departure details can be delayed with "standby for departure", one needs to give some flight path information in the hope that if there is an unannounced VFR pilot there, s/he'll speak up if there's a conflict. :mad:

Have heard that in addition to the two previously reported NAS rollback options (i.e. changing some portions of E back to C), QF have come up with a third, namely extending the Class D above tower airspace to a higher level (it is currently 4,500). I assume the reason is that - currently - VFR aircraft require a clearance to operate in D, thus they will be "known" to ATC.

Interestingly the "QF option" is said to be the result of a meeting with their ops executives, chief pilot and - one RHS.

Listen to QF!
 

This is a great solution to the present problem. Might I suggest that they should just extend the top of Class D to 10,000 feet MSL everywhere in Australia? It's easy to remember.

Allegheny County Airport, the secondary airport to Pittsburgh has a radar repeater in the control cab. They are Class D, yet they have some knowledge as to what is where. This is about survival guys!

My three recommendations are:

1. Bring back Flight Service and allow VFR pilots to file radio-report driven flight plans, with estimates over concurring waypoints.

2. Expand radar coverage and the staffing of area control centres. At the same time, define frequency boundaries so that VFR and IFR are talking on the same freqs.

3. Introduce Class B Airspace at all capital city airports and expand the boundaries of Class D and C airspace.

The first one may seem like a step backward, but it's really not. Australia will never have the tax base to support nationwide radar coverage. In this era of GPS it is tempting to plug in coordinates and wait for the destination, but everyone should get their charts back out and figure where each aircraft is.


There you have it: an airspace that observes the spirit of the Australian environment, but doesn't endanger peoples lives.

Voices, every time I read one of your posts I think "Please, someone who has a say in all this TAKE NOTE OF WHAT IS WRITTEN HERE. For all of your inciteful and sage comments however, you make the assumption that the powers at be are reasonable. This assumption, sadly, is false. You are correct in stating that it should not require a great deal of effort, but unfortunately ANY effort is too much for these people. :yuk:

Airspace Classification
 

No two airports are alike, and no one airspace solution will cure all the ills one may believe exist with the current scheme. In the USA, there are many, many towered airport with Class D airspace (3-5 nm radius, surface to 2,500 AGL). A large number of these have no radar, or even a feed from an En Route or Terminal facility. Traffic is worked in a "see and avoid" environment, with ATC providing traffic advisories when able. At the tower I work at (125,000 - 156,00 annual ops over the last 10 years, 10% of that large turbine air carrier), this is an acceptable and apparently safe way of doing business. In the 12 years I have been at this tower, there have been 3 near miss reports filed involving an Air Carrier aircraft, and one mid air involving two small aircraft (this was outside of controlled airspace, one of the contributing causes of this incident was a pilots failure to announce his position on the common traffic frequency).

Let's turn the situation around as an example. I certainly would be opposed to any effort to increase my span of control (reponsibility), without the necessary tools with which to accomplish it (radar). Why would a tower controller want to be responsible for aircraft so far away from the runway? Our priority starts at the runway, and decreases the further from the runway you get. I would hate to have to explain why I allowed a mishap to occur on my runway because I was talking to a VFR aircraft 20 miles away. I would also be uncomfortable explaining why I allowed two aircraft to "get together" 20 miles from the airport, when I was supposed to be controlling them. Unless you absolutely shut down the airspace and allow one-in, one-out, you will never have positive control over aircraft in your airpsace. With apologies to the pilots reading this, they will usually tell a controller what they think the controller wants to hear.

ATCNorth ,

Couldn't agree with you more.

The original AMATS model and research sought to make our Class D TWR's the same as the US "VFR Tower"; the principal being that a Class D TWR shouldn't be controlling what they can't see with a pair of binoculars. Any IFR feed would be from the CTR, either radar or procedural.

The effect of this transformation was exactly what happens when you try to transfer a model using words not use and practise. Our Class D's control traffic miles away from the airport up to 8,500 [YMAY] in some cases.

Chris ,

You may not realise that you don't need to "bring back FS" to do the job you mention. NAIPS is our version of DUETS which easily enables the same thing without the former costs in staffing.

G'day ;)

Just to clear something up straight away....

ATCNorth is not a controller. The post looks like it was written by Dick himself (or one of his followers). It is verbatim the BS Dick spouts about controllers crashing planes because they are only capable of seperating close to the runway, one conflict at a time.

In Australia ATCNorth, due to cost cutting, efficiency gains, or whatever you want to call it, combined with relatively low traffic loadings, controllers can provide 3 or 4 types of service to different aircraft simultaneously. That's why ATC is cheaper in oz than in either the US or Europe (Eurocontrol figures).

Here's a tip, Dick. You obviously have no understanding of how controllers do their job, and others have tried to explain, but the distance from the field thing is just a crock. Sure, they are controlled differently when you can't see them, but not worse
I'll let someone else answer that.

Ferris, you just might be right:

What controller uses language like that; ATCNORTH, please... It's ok to have a crash at 3 miles(10, 20, 30), as long as it's not on your precious bit of TAR, oh please, take your hand off it....
HO HUM... Done ATC long have you...

Bottle of Rum

Chris,

The technology associated with ADS-B will soon make radar a thing of the past...remember 8-track players.

Ferris and SM4 Pirate are correct. ATCs in Oz do a multitude of tasks, including flight info service and traffic. If you need weather or notams we can call it up, or transfer you to flightwatch(there job anyway) who can get it even faster.

Radar is expensive to install and expensive to maintain. We already have ADS on the large aircraft like B744, B777, A340/330 etc. The next step is to go with the small aircraft derivative ADS-B.

Would you believe that ADS is more accurate than radar. Yep!

BTW, I think ATCNORTH might just not actually have anything to do with ATC either given his language and his attitude. Take a look at towers like Coffs Harbour, Mackay and Tamworth to see how far out from the runway their airspace extends. Heeard of Tower/App. Hmmmm.

Another give away to the fact that he is not who he says he is, is that a controller from Alaska posts for the first time ever on of all places the Downunder and Godzone forum??? Come on!!! When you first register on here, surely your first post would be something closer to home, or the ATC forum, or Jetblast but not an Australian (and sorry Kiwi also!!) forum. Seems very suspicious to me as well.

ADS and 8 Tracks...
 

Yeah, I agree about the technology around the corner for future sat based seperation on small aircraft, but it will be met with resistance in the Australian GA community.

Why?

Because we still have 1977 Warriors with 16,000 hours on their airframes with old KX177B radios in them and owners sneaking MOGAS in their 150s without STC approval letters.

Dick Smith has always been one to reduce the elitism of aviation by trying to make everything simple, free and unrestrictive. As all of you are aware...aviation was never capable of being any of those things.

I agree about extending the authorities of ATC in Australia, and if you really feel that coverage can be extended to allow seperation from light aircraft and RPT jetliners along normal descent profiles, then by all means, your plan should be used.

Remember, that's what all conflicts are normally about. People take a specialised role in society these days and nobody can see another way of looking at a problem. That's why consultants get paid so much.

The answer is for the entire industry to meet, even the military, AOPA, CASA, ATC unions, Virgin, QF, Link and flying schools and figure out, with some kind of mediation what's best.

agree with ATCnorth, US airspace is 100% less confusing than ozzie airspace. The 10,000 and 2500 caps on the airspace work fine and I'm not sure that procedural separation is any safer than the eyes in the tower separation deal. While they're at it why don't they raise the min pressurization altitude to 14,000 too. I don't think there's too many hypoxic pilots crashing over here.

There are a lot of similarities in terminal air traffic issues, regardless of national boundaries. Small, low traffic volume fields with no radar coverage and occasional instrument and large aircraft traffic. How best to serve the users at these locations should be driven by what the user needs, not by what can be provided, as Ferris indicated:

The aviation culture of a given country drives the need a lot. In the US a pilot only expects mandatory participation in an air traffic service when in an area of higher density traffic, such as in the vicinity of a tower controlled airport. Once clear of the traffic pattern and out of the surface area, they know they are increasingly responsible for seeing and avoiding other traffic. In my AT culture, its difficult for me to see what service I could possibly provide to a VFR aircraft more than 5 miles from the field. In response to SM4 Pirate -

Its not that I think we should dodge responsibility, but I only think I should be responsible for what is reasonable. US Class D airspace ends at 3nm. If two aircraft get together at 10, 20 or 30 miles, what could I have done with a pair of binoculars and a radio?

We have demonstrated a high level of safety with minimal air traffic intrusion, for a long time. Before the alphabet airspace came along, our airport traffic areas were no larger than 5 miles. As an outsider looking in, I think you would relieve yourself of a level of risk and responsibility, without degrading safety, while allowing pilots the freedom to do their pilot thing, by reducing the size of the airspace your responsible for.

Just for the record, I am a tower controller. Have been for 26 years.

druglord said:

While they're at it why don't they raise the min pressurization altitude to 14,000 too. I don't think there's too many hypoxic pilots crashing over here.


Since when has there been a "Minimum pressurization altitude"?.

Maybe he's talking about Oxygen requirements, if so, that's (basically) 10,000 feet here and 12,500 in the US. Where does 14,000 feet come from?

Just keep digging that hole............

This may come as a shock to you "ATCNorth", but real air traffic controllers control aircraft across oceans, sometimes high up in the sky- lots of times when they can't see them with binoculars. Thay often have pieces of airspace much larger than 5 miles. So keep making stupid statements like Helps clarify that you are a liar.

It's really sad that Dick (or whoever this pretender is) has to try and use this sort of tactic to gain support. All it does is harm your argument. Do you get that? How true that statement is.

Fare-paying passengers in RPT jets deserve the protection of ClassC, the very thing they were satisfactorily (and cheaply) provided with prior to this debacle. Spoken like a true VFR pilot. How about; stopping the VFR pilot getting cleaned up by a jet that he has no hope of avoiding, even if he sees it? Like in the LT incident.

As a 'controller' with '26 years experience', I'm sure you'll be able to thumb thru the crash mags when it's quiet, and work out which of those 35 aircraft lost in midair collisions every year (on average- 1992-2002 U.S.) would've benefitted from a control service ! :hmm:

Dick, get off the phone and listen!
 

ATCNORTH Said:Agreed. Had AusNAS been subjected to local Aeronautical studies that take account of local peculiarities, most of the safety issues would have been addressed by the correct application of ICAO airspace classifications. THAT HAS NOT HAPPENED!Yep! We call these GAAP (General Aviation Airport Procedures). These were designed for use in OZ with “Non RPT” operations. GAAP procedures were deemed UNSUITABLE for RPT because of the unacceptable risk of “Un-alerted See and Avoid” collision. In IMC it is one in, one out. WOW, “Worlds Best Practice” eh!Would that tower be in Alaska? Ever worked at either of the 2 IFR class D towers in the US? Have you been speaking to Mr Smith or rather has he been SPEAKING AT YOU?

Big Stats mean jack****e!. I have previously worked at one of the GAAP towers here in Oz, similar movement rates with a triple parallel arrangement. That experience gives me every reason to consider that perhaps “see and avoid” only works adequately when it is “Alerted” i.e. directed traffic information!How many airprox events have you seen that go unreported? How close is too close to warrant a “fizzer” eh?
3 Air carrier incidents. Jeez they must have been rippers! Pilots must have been bent all outa’ shape for you to bother with an airprox report in that sort of VFR environment!
You maintain it is an acceptable and apparently safe way of doing business, well good for you and the unsuspecting American travelling public. It don’t cut the mustard here ol’ bean, and this ain’t the US of A.Yep, see in OZ, these poor people would more than likely have been inside controlled airspace with a clearance and positively separated or segregated in our class D and C arrangements, amazing how not making an area broadcast caused a midair that far away for the aerodrome eh! What frequency was the other aircraft on? I guess you never found that out as they were likely a smoking hole in the dirt after the fact!Radar, nice to have, certainly NOT NECESSARY. If you are trained to separate/segregate procedurally and pilots know the frequencies and airspace classification (service level) can pick up the Mic and speak whilst holding the PTT at the same time, the system can return very good safety and expedition. If you know what you are doing, it is not that challenging really!.Well, of course you would. Completely understandable response when you are trained to only provide “Traffic information and runway separation” to those you can see. What we would call Flight Service (DTI) with a runway chaser!
Perhaps you have little experience in procedural Approach/Departures standards and practices (Vertical, Lateral - Visual geographical and or VOR/DME/GPS, Longitudinal DME, Arriving DME/GPS, Timed departures 1,2 and 5min, Projected flt path, Segregated flt path etc etc).

Ask Dick to fly you out to Oz and we will show you how to “separate/segregate” multiple Arriving and Departing IFR/IFR (In IMC) and IFR/IFR/VFR (In VMC). It works a treat and is very safe, the statistics support that.
As has been said numerous times before, a much better use of ATC services to industry than your more expensive “traffic was” worlds best practice!.Quite right when you play with a little zone of 3 or so miles. See above!Perhaps this statement says more about your pilot culture than anything else. Oz Pilots almost without exception make accurate call’s cognisant of the safety ramifications of false or misleading information.
Culture, it might make an interesting comparison when considering objectively which country stood closest to the benchmarks of "Worlds best practice” in Airspace Management.Agreed. How then should that be assessed?. Aeronautical Studies prior to DOWNGRADING of services, perhaps, maybe?See Above!Clearly you have little or no IFR procedural App/Dep experience otherwise you could not make such an uniformed statement. Your own association NATCA supports our concerns!
Your “little D” system is being rammed down our throats, not the other way around. I would not be so arrogant as to tell you what you should have in the US. How bout extending us the same courtesy?See above! With respect you have NO IDEA!Mid-Air and Airprox statistics in your country do not support that statement when compared to the record in CTA/CTR ATS in Oz!Dick Smith, one of a handful who wanted this AusNAS system is the one who wants as you put it ATC’s relieved of their responsibilities.
Blind freddy can see the end-state of this crap, his perceived culture of “baggage handler Unicoms” and “CTAF free for all’s” to attempt to ameliorate his “Location Specific Overcharging” disaster!
No gloss or spin can ever give legitimate support to the notion that AusNAS does not degrade safety!.
There is the Cultural divide right there! We don’t want what you are selling, period!.If that is true, shame on you!!! Please pass on our best regards to "Bickieman" when next you talk to him!

DruglordWhy is that oh wise one?
- Radar coverage?
- Maps that tell ya nothing cause ignorance is bliss?Really? I’m damn sure you’re not sure!:hmm:

Let's follow the US model and change our D class towers to 3-5nm radius up to 2,500', with E airspace above.

This will free up the towers to concentrate on their circuit traffic.

Meanwhile, one of the two Centres will be responsible for the overlying E airspace. The controller will be in a room that could be up to a 1000nm away.
- No radar.
- En-route procedural separation standards that are more restrictive than those that are exclusively used by
towers.
- No opportunity to use visual separation.
- Little local knowledge.
- Vast increase in workload, both a/g and unit to unit coordination.

Sounds like a good deal for the towers.

CG

CG, You've nailed it.

Now how do I get in the tower stream...?

Mind you once you do all that to the towers and enroute, you won't need a tower as enroute own down to A025 anyway.

Bring on the US CTAF's they are much more efficient than our little D towers and MBZs.

There's your 200 ATC jobs, no outstation towers or managers to support them.

SM4 Pirate

The controllers would go, but I'm sure the managers would stay.
:bored: :ugh: :uhoh: :yuk: