Airspace Design - Some Background
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Airspace Design - Some Background
Airspace Design – Some Background
We have been watching the “comings and goings” over airspace management issues in Australia – and in other countries – for several years, both on PPRUNE, and in your press. We don’t often proffer an opinion in this or other forums, leaving that for more erudite contributors – however, we are moved to contribute in this instance to place some balance into your sometimes emotive arguments.
Perhaps a historical lesson might help your perspectives, and focus your debate[s]:
The current so-called “alphabet” Airspace Classification System was developed by a technical panel of the Air Navigation Commission [ANC] of the International Civil Aviation Organization [ICAO] in the late 1980’s. That panel was called the Visual Operations Panel [VOP] – and, as the name implies, was tasked with codifying and facilitating the operation of VFR flights within the airspace systems of the world. The panel comprised “technical experts” from the United States, Canada, Australia, the United Kingdom, European States, and other States.
Until ICAO promulgated the airspace classification table and [less than] descriptive paragraphs in 1991, there was no uniform method to describe or codify certain common elements of VFR and IFR flight. Some States operated systems using terms like Visual Exempt, Instrument Visual, Controlled and Uncontrolled and so on. It wasn’t only the terminology that differed – it was the application.
The VOP, in addition to developing the currently adopted “alphabet” codes, also developed a framework that would allow States to determine the need – or otherwise – for certain airspace management practices, based on the changing risk to IFR operations of increasing numbers of VFR operations. You need to access and examine the suite of working papers that supported the classification system to fully understand the intent. You also need to see the draft guidance material that was developed by VOP – none of this was ever published by ICAO.
We have seen that material - it CLEARLY enunciates a framework where IFR operations with very few proximate VFR operations should be contained within a low third party intervention environment – i.e., Class G – BUT as the amount of traffic – IFR and VFR increases – AND the potential risk levels increase – the level of intervention capability – OR the amount of restriction on VFR flights – changes. The KEY is that the level of risk that IFR flights are exposed to remains within a [relatively] constant band. Class A was NEVER meant to afford a higher level of protection to IFR flights that Class G. The level of risk to IFR flights was meant to be maintained at an appropriate SAFE and COST-EFFECTIVE level by regulating the services provided to IFR - and the restrictions placed on VFR operations [when in proximity to IFR operations].
Hence, you’ll [no doubt] notice that for all intents and purposes, there is little or no difference to the set of operating parameters for IFR flights in the airspace tables, from Class G to Class A – BUT the services and restrictions on VFR operations change substantially as you move from Class G to Class A.
The VOP guidance material also discusses in some detail the operation of jet aircraft at various speeds in relation to VFR flights, the ability of IFR pilots to break from cloud and “see” VFR flights and so on. Hence the use of differing “clearance from cloud” requirements. There was a good deal of science behind the standard – just not enough background or guidance material to see it implemented uniformly – not just in your country, but around the world.
So, it is somewhat amusing to see the endless arguments that are taking place in Australia over the need, or otherwise, for a class of airspace here, or a level of service there – when it is clear that very few people – least of all your airspace designers - understand the background to the airspace classification system at all.
Now on the matter of transponder operation. In the late 1980’s, when VOP was doing its work, transponders were used by higher end IFR operations, and lower end where possible – but were not widely fitted to VFR aircraft. Equally, whilst some major States and Regions [USA, Europe] had widespread secondary radar coverage, few other States had secondary surveillance radar. Most certainly, the development of collision avoidance systems was embryonic. Hence, the classification system – published in 1991 - omits reference to transponder carriage and activation.
Does the use of transponders mitigate risk – most certainly – but from an airspace design viewpoint, you can ONLY factor that risk mitigation where a third party service [advisory or control] is being used. That is, it aids surveillance, which aids the provision of [meaningful] services to aircraft – IFR or VFR. That means that in certain cases, in radar coverage in particular, the carriage and operation of transponders may allow an airspace designer to impose a lesser classification of airspace. The continental portion of the United States of America is a good example, where the high [but not total] coverage by secondary radar allows the application of Class E, rather than Class C, airspace.
You CANNOT [yet], however, design a system that relies on aircraft-to-aircraft surveillance or separation based on the use of transponders – that is, the use of airborne collision avoidance systems, like TCAS and Mode A/C transponders, as an airspace design tool, is prohibited. You may want to have this verified [we understand you have a member on the ICAO Air Navigation Commission]. Effectively, ICAO – and the ANC specifically – has determined that ACAS MAY NOT be used as a risk mitigator under any circumstances in the design of airspace management procedures. ALL ICAO Technical Panels have been directed that they may not factor such systems in the development of separation standards, the design of procedures, or the development of future systems. ACAS is a “last line of defence” for pilots – NOT a system design tool.
We are dismayed to read in some of your postings – and in education material we have seen associated with your recent changes – that pilots are being instructed that TCAS is a design risk mitigator. We suspect that Australia will run a fairly solid gauntlet of international condemnation should that be the case.
Good luck.
The Voices of Reason
We have been watching the “comings and goings” over airspace management issues in Australia – and in other countries – for several years, both on PPRUNE, and in your press. We don’t often proffer an opinion in this or other forums, leaving that for more erudite contributors – however, we are moved to contribute in this instance to place some balance into your sometimes emotive arguments.
Perhaps a historical lesson might help your perspectives, and focus your debate[s]:
The current so-called “alphabet” Airspace Classification System was developed by a technical panel of the Air Navigation Commission [ANC] of the International Civil Aviation Organization [ICAO] in the late 1980’s. That panel was called the Visual Operations Panel [VOP] – and, as the name implies, was tasked with codifying and facilitating the operation of VFR flights within the airspace systems of the world. The panel comprised “technical experts” from the United States, Canada, Australia, the United Kingdom, European States, and other States.
Until ICAO promulgated the airspace classification table and [less than] descriptive paragraphs in 1991, there was no uniform method to describe or codify certain common elements of VFR and IFR flight. Some States operated systems using terms like Visual Exempt, Instrument Visual, Controlled and Uncontrolled and so on. It wasn’t only the terminology that differed – it was the application.
The VOP, in addition to developing the currently adopted “alphabet” codes, also developed a framework that would allow States to determine the need – or otherwise – for certain airspace management practices, based on the changing risk to IFR operations of increasing numbers of VFR operations. You need to access and examine the suite of working papers that supported the classification system to fully understand the intent. You also need to see the draft guidance material that was developed by VOP – none of this was ever published by ICAO.
We have seen that material - it CLEARLY enunciates a framework where IFR operations with very few proximate VFR operations should be contained within a low third party intervention environment – i.e., Class G – BUT as the amount of traffic – IFR and VFR increases – AND the potential risk levels increase – the level of intervention capability – OR the amount of restriction on VFR flights – changes. The KEY is that the level of risk that IFR flights are exposed to remains within a [relatively] constant band. Class A was NEVER meant to afford a higher level of protection to IFR flights that Class G. The level of risk to IFR flights was meant to be maintained at an appropriate SAFE and COST-EFFECTIVE level by regulating the services provided to IFR - and the restrictions placed on VFR operations [when in proximity to IFR operations].
Hence, you’ll [no doubt] notice that for all intents and purposes, there is little or no difference to the set of operating parameters for IFR flights in the airspace tables, from Class G to Class A – BUT the services and restrictions on VFR operations change substantially as you move from Class G to Class A.
The VOP guidance material also discusses in some detail the operation of jet aircraft at various speeds in relation to VFR flights, the ability of IFR pilots to break from cloud and “see” VFR flights and so on. Hence the use of differing “clearance from cloud” requirements. There was a good deal of science behind the standard – just not enough background or guidance material to see it implemented uniformly – not just in your country, but around the world.
So, it is somewhat amusing to see the endless arguments that are taking place in Australia over the need, or otherwise, for a class of airspace here, or a level of service there – when it is clear that very few people – least of all your airspace designers - understand the background to the airspace classification system at all.
Now on the matter of transponder operation. In the late 1980’s, when VOP was doing its work, transponders were used by higher end IFR operations, and lower end where possible – but were not widely fitted to VFR aircraft. Equally, whilst some major States and Regions [USA, Europe] had widespread secondary radar coverage, few other States had secondary surveillance radar. Most certainly, the development of collision avoidance systems was embryonic. Hence, the classification system – published in 1991 - omits reference to transponder carriage and activation.
Does the use of transponders mitigate risk – most certainly – but from an airspace design viewpoint, you can ONLY factor that risk mitigation where a third party service [advisory or control] is being used. That is, it aids surveillance, which aids the provision of [meaningful] services to aircraft – IFR or VFR. That means that in certain cases, in radar coverage in particular, the carriage and operation of transponders may allow an airspace designer to impose a lesser classification of airspace. The continental portion of the United States of America is a good example, where the high [but not total] coverage by secondary radar allows the application of Class E, rather than Class C, airspace.
You CANNOT [yet], however, design a system that relies on aircraft-to-aircraft surveillance or separation based on the use of transponders – that is, the use of airborne collision avoidance systems, like TCAS and Mode A/C transponders, as an airspace design tool, is prohibited. You may want to have this verified [we understand you have a member on the ICAO Air Navigation Commission]. Effectively, ICAO – and the ANC specifically – has determined that ACAS MAY NOT be used as a risk mitigator under any circumstances in the design of airspace management procedures. ALL ICAO Technical Panels have been directed that they may not factor such systems in the development of separation standards, the design of procedures, or the development of future systems. ACAS is a “last line of defence” for pilots – NOT a system design tool.
We are dismayed to read in some of your postings – and in education material we have seen associated with your recent changes – that pilots are being instructed that TCAS is a design risk mitigator. We suspect that Australia will run a fairly solid gauntlet of international condemnation should that be the case.
Good luck.
The Voices of Reason
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A somewhat interesting post. My first question for you is who is WE? You refer to WE often and i would like to know who you are posting on behalf of.
I think you and I are on the same side with your last paragraph about TCAS separation. Is this the intent of the post? There is much talk of unrealeased documentation and hearsay. From what i can gather you would have us in Austraia designate Airspace above f180 as class G not A as stands now
and also have curent G as B as that is where the most IFR v VFR risk is therefore more intervention required
Are we to believe that the entire world has got this backwards?
While your final point to do with TCAS is in my opinion valid, your method or arriving there is not.
I think you and I are on the same side with your last paragraph about TCAS separation. Is this the intent of the post? There is much talk of unrealeased documentation and hearsay. From what i can gather you would have us in Austraia designate Airspace above f180 as class G not A as stands now
it CLEARLY enunciates a framework where IFR operations with very few proximate VFR operations should be contained within a low third party intervention environment – i.e., Class G
IFR and VFR increases – AND the potential risk levels increase – the level of intervention capability – OR the amount of restriction on VFR flights – changes. The KEY is that the level of risk that IFR flights are exposed to
Are we to believe that the entire world has got this backwards?
when it is clear that very few people – least of all your airspace designers - understand the background to the airspace classification system at all.
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Marvellous dissertation, how would the current airspace debacle look if somebody had held a meeting with this document as a starting point instead of letting others do what they want because the p1ssweak minister is frightened of them...
Every meeting I have attended that has discussed mitigation has started with the frenzied yelp "TCAS is not a mitigator for any stage of NAS" (usually followed by "Nothing you say will actually change part of the model").
However, from what the "voices" are telling me (I hope this sentence isn't quoted in my next medical) those high volume areas outside radar coverage (YMAY, YMHB, YBAS for eg.) should be C unless we ARE using TCAS as a mitigator. Sounds good to me, we don't have the radar coverage of Gooberland.
Every meeting I have attended that has discussed mitigation has started with the frenzied yelp "TCAS is not a mitigator for any stage of NAS" (usually followed by "Nothing you say will actually change part of the model").
However, from what the "voices" are telling me (I hope this sentence isn't quoted in my next medical) those high volume areas outside radar coverage (YMAY, YMHB, YBAS for eg.) should be C unless we ARE using TCAS as a mitigator. Sounds good to me, we don't have the radar coverage of Gooberland.
Last edited by Woomera; 2nd Feb 2004 at 13:04.
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Airspace Design - Some Background
It is difficult to answer all your questions in one limited post, particularly in a subject as complex as airspace design, where the genuine and immutable need to ensure safety needs ALWAYS to be balanced against the cost-effectiveness of achieving that end – AND the need to ensure amenity [that is, access to the airspace by those who want, but perhaps inevitably won’t be able, to operate there].
The Visual Operations Panel to which we referred was challenged to address the legitimate concerns of IFR operators, who were operating increasingly complex and higher energy [higher performance] aircraft in proximity to increasing numbers of VFR flights. The target was to allow those VFR operations to continue with as few limitations as possible [it was, after all, a VISUAL operations panel] – BUT where necessary [Class A] exclude them.
We don’t know the specific mechanics of your airspace – but you are undoubtedly not unique – though we recognize that EVERY country has its unique characteristics. VFR aircraft operators around the world howl whenever their amenity is challenged – and many IFR pilots that you speak to would prefer Class A across the world [try the Russian Federation!].
There are four keys to [good] airspace design. The first is to determine the level of risk - not just across the whole environment [this can give mis-leading results] but also in individual environments – each has its own idiosyncrasies. You don’t need to apply high levels of science to do this – there are many methods for assessing risk – but you do need to be able to defend any risk assessment that you make - that necessarily means openness. That also does not mean that you need to ameliorate the concerns of all airspace users – BUT you must be able to demonstrate that you have [genuinely] listened to their concerns – AND sought to factor those concerns in your decision making processes.
The second is to find as uniform a set of airspace classifications as possible, that will “fit” the risk profiles. What we mean here is to choose as few rule sets as is feasible. Simply because there ARE seven airspace classes, does NOT mean you need to use them all. Our experience is that pilots and service provider staff like to keep things simple – safety thrives on simplicity.
The third step – and this is critical – is to test and evaluate the risk mitigations offered by the classification – e.g., will applying clearances to VFR flights mitigate the risk, will excluding VFR flights mitigate the risk, will it be an unnecessary impost to restrict VFR operations, and so on.
This will leave you, inevitably, with a patchwork quilt of airspace classes. So, your fourth step – and many countries [see the Eurocontrol web-site for diagrams of the biggest patchwork quilt of all] don’t take it – is to rationalize the mix of airspace classes, or procedures. So if you determine that you should have Class C in one area, Class D adjacent to that airspace, and then Class E adjacent to that airspace – AND it would cost you no more to make it all Class C – then that should be your decision. If there is no cost impact – and no demonstrable negative impact on amenity for a VFR flight – nothing in the “rule book” says you can’t exceed the “minimum requirement”. If you exclude a very small number of Class B airports in the United States, there are really only 4 of 7 classes applied. Do they need Class A above FL180 – in many cases no. If they had A, B and C, the rule set becomes too complex. Could the United States apply larger volumes of Class G – yes – but again the mix of rule sets would make it more complex.
It is interesting to note that in the Eurocontrol documentation, they have established a target of unifying airspace classifications across Europe into three by 2010 – in a framework of better efficiency and better access and equity – NOT in a framework of restrictive practices.
Before we close – a respondent made a reference to our organizational allegiance. We do not represent anyone or any organization. We are concerned that many decisions made not only in your country, but in many others, are based not only on [hopefully] mis-understanding – but also [hopefully not] on deliberate mis-interpretation. We are concerned about safety – and we are concerned that any money that is spent on airspace management is correctly applied to ensure safety, without unnecessarily restricting the amenity of any user.
The Visual Operations Panel to which we referred was challenged to address the legitimate concerns of IFR operators, who were operating increasingly complex and higher energy [higher performance] aircraft in proximity to increasing numbers of VFR flights. The target was to allow those VFR operations to continue with as few limitations as possible [it was, after all, a VISUAL operations panel] – BUT where necessary [Class A] exclude them.
We don’t know the specific mechanics of your airspace – but you are undoubtedly not unique – though we recognize that EVERY country has its unique characteristics. VFR aircraft operators around the world howl whenever their amenity is challenged – and many IFR pilots that you speak to would prefer Class A across the world [try the Russian Federation!].
There are four keys to [good] airspace design. The first is to determine the level of risk - not just across the whole environment [this can give mis-leading results] but also in individual environments – each has its own idiosyncrasies. You don’t need to apply high levels of science to do this – there are many methods for assessing risk – but you do need to be able to defend any risk assessment that you make - that necessarily means openness. That also does not mean that you need to ameliorate the concerns of all airspace users – BUT you must be able to demonstrate that you have [genuinely] listened to their concerns – AND sought to factor those concerns in your decision making processes.
The second is to find as uniform a set of airspace classifications as possible, that will “fit” the risk profiles. What we mean here is to choose as few rule sets as is feasible. Simply because there ARE seven airspace classes, does NOT mean you need to use them all. Our experience is that pilots and service provider staff like to keep things simple – safety thrives on simplicity.
The third step – and this is critical – is to test and evaluate the risk mitigations offered by the classification – e.g., will applying clearances to VFR flights mitigate the risk, will excluding VFR flights mitigate the risk, will it be an unnecessary impost to restrict VFR operations, and so on.
This will leave you, inevitably, with a patchwork quilt of airspace classes. So, your fourth step – and many countries [see the Eurocontrol web-site for diagrams of the biggest patchwork quilt of all] don’t take it – is to rationalize the mix of airspace classes, or procedures. So if you determine that you should have Class C in one area, Class D adjacent to that airspace, and then Class E adjacent to that airspace – AND it would cost you no more to make it all Class C – then that should be your decision. If there is no cost impact – and no demonstrable negative impact on amenity for a VFR flight – nothing in the “rule book” says you can’t exceed the “minimum requirement”. If you exclude a very small number of Class B airports in the United States, there are really only 4 of 7 classes applied. Do they need Class A above FL180 – in many cases no. If they had A, B and C, the rule set becomes too complex. Could the United States apply larger volumes of Class G – yes – but again the mix of rule sets would make it more complex.
It is interesting to note that in the Eurocontrol documentation, they have established a target of unifying airspace classifications across Europe into three by 2010 – in a framework of better efficiency and better access and equity – NOT in a framework of restrictive practices.
Before we close – a respondent made a reference to our organizational allegiance. We do not represent anyone or any organization. We are concerned that many decisions made not only in your country, but in many others, are based not only on [hopefully] mis-understanding – but also [hopefully not] on deliberate mis-interpretation. We are concerned about safety – and we are concerned that any money that is spent on airspace management is correctly applied to ensure safety, without unnecessarily restricting the amenity of any user.
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Airspace Design - Some Background
To TOBZALP,
We have just re-read your intervention - and you are correct - having re-read our original post, we may not have been clear. Our apologies. There must be absolutely no misunderstanding that IFR to IFR operations deserve a constant level of protection - and a constant level of protection in relation to their interaction with VFR flights. The VOP intended that for Classes A, B, C, D and E, the levels of service to IFR aircraft in respect of other IFR aircraft is IDENTICAL. The varying classifications refer to the levels of interaction between IFR and VFR aircraft. In response to your comment about Class G above 18,000 feet - though not fully familiar with your airspace, we suspect that you are being facetious - we would expect that high performance IFR aircraft are likely to interact with other high performance IFR aircraft in that domain - clearly some level of control type services would be advocated.
In respect to your intervention on airborne collision systems, we would ask that you do access ICAO documentation - or at the very least access your officials in ICAO. ICAO is categoric in its views on the use of ACAS systems in airspace design. If we were less than clear in our statements, we apologize.
If our views are not helpful, we will, of course, withdraw from your forum. We seek only to offer the benefit of experience in these matters - and to offer sources of information which you may use to the benefit of aviation safety in your country. From what we have observed, you are fighting misinformation - skillfully manipulated - but incorrect, nonetheless. We can provide assistance to discredit such misinformation, and point you to correct source material.
We have just re-read your intervention - and you are correct - having re-read our original post, we may not have been clear. Our apologies. There must be absolutely no misunderstanding that IFR to IFR operations deserve a constant level of protection - and a constant level of protection in relation to their interaction with VFR flights. The VOP intended that for Classes A, B, C, D and E, the levels of service to IFR aircraft in respect of other IFR aircraft is IDENTICAL. The varying classifications refer to the levels of interaction between IFR and VFR aircraft. In response to your comment about Class G above 18,000 feet - though not fully familiar with your airspace, we suspect that you are being facetious - we would expect that high performance IFR aircraft are likely to interact with other high performance IFR aircraft in that domain - clearly some level of control type services would be advocated.
In respect to your intervention on airborne collision systems, we would ask that you do access ICAO documentation - or at the very least access your officials in ICAO. ICAO is categoric in its views on the use of ACAS systems in airspace design. If we were less than clear in our statements, we apologize.
If our views are not helpful, we will, of course, withdraw from your forum. We seek only to offer the benefit of experience in these matters - and to offer sources of information which you may use to the benefit of aviation safety in your country. From what we have observed, you are fighting misinformation - skillfully manipulated - but incorrect, nonetheless. We can provide assistance to discredit such misinformation, and point you to correct source material.
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Is it just me?
Tobzalp et al.
Is it just me or does the "Voices of Reason" posts sound like the benevolent aliens (like the Asgards off Stagate SG1) have decided to help us mere mortals.
Sorry to sound cynical Voices of Reason, but we really could have used your help before the NAS mess started. Your reasoned argument and historical background make sense and its a pity some of it wasn't given to the ARG responsible for the airspace disaster we're in.
Maybe some of your posts and information could be given to ATSB and CASA so the airspace can be fixed.
Anyway, thanks for giving us the lowdown on airspace development history at the international level.
Is it just me or does the "Voices of Reason" posts sound like the benevolent aliens (like the Asgards off Stagate SG1) have decided to help us mere mortals.
Sorry to sound cynical Voices of Reason, but we really could have used your help before the NAS mess started. Your reasoned argument and historical background make sense and its a pity some of it wasn't given to the ARG responsible for the airspace disaster we're in.
Maybe some of your posts and information could be given to ATSB and CASA so the airspace can be fixed.
Anyway, thanks for giving us the lowdown on airspace development history at the international level.
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Airspace Design - Some Background
Dirty Pierre,
Points taken - and no, we are not "benevolent aliens" - we were pointed to your airspace debate by "interested parties" in your country who thought we might be able to offer assistance.
We have found that truth sometimes gets [deliberately or accidentally] covered-up, and buried in red-tape, so that untruths can flourish.
There is a powerful instrument used in the United States of America, and around the world, to cut through this "red tape subterfuge" - it is known as FREEDOM OF INFORMATION. It is usually relatively inexpensive to access any relevant information from government and semi-government organizations. BUT you must be specific in what you request.
Might we suggest that rather than exchange frustrations on this site - clearly not heeded by your airspace designers - that you access ALL of the information on which their decision making is based - you might be [very] surprised at what you uncover.
We would suggest two mechanisms. First, as we said - be very specific in your request. Do not simply ask for airspace documents - ask for documents relating to every name and iteration over the last several years. We think you have had NAS, Class G Demonstrations, LAMP, Airspace 2000 and so on. Make sure you ask for information at EVERY level in the organization - not just at senior executive level.
The second is to establish a credible [to you] framework in which to request and analyse the information - that could be done by partnering with an interested party - such as your aviation investigation body - or if you are serious, with a dedicated newspaper reporter. You might find that the latter is less manageble [obviously reporters have particular reasons for participating] - but might accelerate the process so that your aviation investigation body is DIRECTED to act [we suspect you will understand what we mean].
If we can be of assistance, please post accordingly.
Points taken - and no, we are not "benevolent aliens" - we were pointed to your airspace debate by "interested parties" in your country who thought we might be able to offer assistance.
We have found that truth sometimes gets [deliberately or accidentally] covered-up, and buried in red-tape, so that untruths can flourish.
There is a powerful instrument used in the United States of America, and around the world, to cut through this "red tape subterfuge" - it is known as FREEDOM OF INFORMATION. It is usually relatively inexpensive to access any relevant information from government and semi-government organizations. BUT you must be specific in what you request.
Might we suggest that rather than exchange frustrations on this site - clearly not heeded by your airspace designers - that you access ALL of the information on which their decision making is based - you might be [very] surprised at what you uncover.
We would suggest two mechanisms. First, as we said - be very specific in your request. Do not simply ask for airspace documents - ask for documents relating to every name and iteration over the last several years. We think you have had NAS, Class G Demonstrations, LAMP, Airspace 2000 and so on. Make sure you ask for information at EVERY level in the organization - not just at senior executive level.
The second is to establish a credible [to you] framework in which to request and analyse the information - that could be done by partnering with an interested party - such as your aviation investigation body - or if you are serious, with a dedicated newspaper reporter. You might find that the latter is less manageble [obviously reporters have particular reasons for participating] - but might accelerate the process so that your aviation investigation body is DIRECTED to act [we suspect you will understand what we mean].
If we can be of assistance, please post accordingly.
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Airspace Design - Some Background
We noticed that an exchange is taking place on a parallel site - dealing with proposed new radio procedures. We noted the detailed reference to incidents, and were surprised to see how many of those incidents were apparently resolved by ACAS systems - not design, and not procedures.
This is a very good example of mis-interpretation and mis-direction attempting to lead you AWAY from a point and not towards it.
As we indicated in previous postings, the use of ACAS systems as a system design tool is specifically and categorically discouraged - not only by the International Civil Aviation Organization - but also by ALL major States and Eurocontrol. Both the International Federation of AirLine Pilots Associations [IFALPA], and the International Federation of Air Traffic Controller Associations [IFATCA] have strong positions on the use of ACAS systems as anything other than last line of defence systems. Even the United States of America would not design a system that relies on ACAS systems. We suspect that a question to the right authority in the Federal Aviation Administration would validate this statement.
Your respondent cites numerous examples where the activation of ACAS systems - whilst preventing a collision - allowed aircraft to operate in dangerous proximity. ACAS systems can and do fail - witness the unfortunate accident at Uberlingen.
What we are saying is that you should NOT be bated by the seemingly "convincing" statistics - they are just that - statistics. We have looked at the web-site of your air investgaion body, and if we are correct, a classification of 4 or 5 means that your investigator was not overly concerned by the incidents.
And yet, in the same breath, your airspace design people are [seemingly] advocating a system that RELIES on ACAS systems to be effective.
We would play this straight back to your designers - challenge them to demonstrate how it can be a dangerous set of incidents on the one hand - yet a key safety design feature on the other.
This is a very good example of mis-interpretation and mis-direction attempting to lead you AWAY from a point and not towards it.
As we indicated in previous postings, the use of ACAS systems as a system design tool is specifically and categorically discouraged - not only by the International Civil Aviation Organization - but also by ALL major States and Eurocontrol. Both the International Federation of AirLine Pilots Associations [IFALPA], and the International Federation of Air Traffic Controller Associations [IFATCA] have strong positions on the use of ACAS systems as anything other than last line of defence systems. Even the United States of America would not design a system that relies on ACAS systems. We suspect that a question to the right authority in the Federal Aviation Administration would validate this statement.
Your respondent cites numerous examples where the activation of ACAS systems - whilst preventing a collision - allowed aircraft to operate in dangerous proximity. ACAS systems can and do fail - witness the unfortunate accident at Uberlingen.
What we are saying is that you should NOT be bated by the seemingly "convincing" statistics - they are just that - statistics. We have looked at the web-site of your air investgaion body, and if we are correct, a classification of 4 or 5 means that your investigator was not overly concerned by the incidents.
And yet, in the same breath, your airspace design people are [seemingly] advocating a system that RELIES on ACAS systems to be effective.
We would play this straight back to your designers - challenge them to demonstrate how it can be a dangerous set of incidents on the one hand - yet a key safety design feature on the other.
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Airspace Design - Background Information
Tobzalp,
WE work through every site in PPRuNe, from time to time, looking for areas where it is obvious that aviation safety is being challenged.
We change our "callsign" on each occasion - however, we maintain absolute consistency in our view that where safety is being challenged - OR where the industry is being subjected to excessive and unnecessary costs - OR where amenity or access is challenged unnecessarily - we will attempt to intervene.
We are located throughout the world - and we are of one mind - safety of aviation - but not at any cost. One life lost unnecessarily is one life too many. Aviation is an expensive business - but the consequences of mistakes in airspace design are very high.
WE work through every site in PPRuNe, from time to time, looking for areas where it is obvious that aviation safety is being challenged.
We change our "callsign" on each occasion - however, we maintain absolute consistency in our view that where safety is being challenged - OR where the industry is being subjected to excessive and unnecessary costs - OR where amenity or access is challenged unnecessarily - we will attempt to intervene.
We are located throughout the world - and we are of one mind - safety of aviation - but not at any cost. One life lost unnecessarily is one life too many. Aviation is an expensive business - but the consequences of mistakes in airspace design are very high.
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Voices of Reason,
I like what you say and how you say it.
Maybe you could answer Dick Smith directly. Mind you he has been very slow in replying to any of your posts.
You still do really sound like the Asgards though. All very mysterious. Maybe you're the prophets from Deep Space Nine?
I like what you say and how you say it.
Maybe you could answer Dick Smith directly. Mind you he has been very slow in replying to any of your posts.
You still do really sound like the Asgards though. All very mysterious. Maybe you're the prophets from Deep Space Nine?
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Class E and Class C Airspace
We have again been directed by respondents to certain sites, and have noted some of the debate over the re-classification of airspace – and the at times spurious arguments that are made for and against the proposed re-classifications. We would offer the following observations, based on ICAO processes, and based on “world best practice”.
Clearly, there is theoretically little or no difference in the levels of service provided between IFR aircraft operating in Airspace Classes A, B, C, D or E. We say theoretical, because in practice, there is a higher potential for tactical – rather than planned - response by IFR flights in relation to VFR flights in Class E airspace, which may impact the ability to offer, or the effectiveness of offered, separation services to IFR flights.
Where the differences occur, of course, is the interaction between IFR and VFR flights. By that, we mean that an IFR aircraft may require services more urgently [i.e., tactically rather than in a planned fashion] in Class E airspace because of the proximity of VFR flights, or may not be able to comply with a planned ATC instruction. This adds a level of complexity to the model – for both pilots and providers of services – something that needs to be factored in the holistic airspace design. That is not to say Class E should not be used – far from it – but it must be appreciated that Class E operates in a fundamentally different way than Classes A through D.
In any given volume of airspace, with the same number of IFR and VFR flights, the level of risk must increase when Class C airspace is changed to Class E [or Class D, or Class F or Class G for that matter]. Equally, a change upwards in classification, from Class C to Class B or Class A, for a given volume of airspace, with the same number of IFR and VFR flights, the level of risk is decreased.
As we have indicated before, the intent of the airspace classification system was to provide a menu of services whereby the levels of risk to all aircraft – but in particular IFR flights – could be maintained within an acceptable band – but without unduly restricting the amenity of VFR flights, and adding unnecessary expense to operators.
We do not dispute the fact that in many instances – and this has occurred around the globe – that the initial transition to the airspace classification system was done without conducting a risk analysis – or identifying what risks were being managed – before the “label” was assigned. This could, of course, result in levels of service that far exceed those truly required in a given volume of airspace. We suspect that this has happened in your country, as it has happened in others.
It will prove almost impossible to develop an airspace model where the level of risk to any particular aircraft or group of aircraft – IFR or VFR – is uniform. As we have mentioned in previous posts, having determined the risk levels, and appropriate classifications, you will need to “smooth” the model, by changing some classifications for the sake of simplicity and uniformity.
Now we need to clarify a point made direct to us by a respondent. We have indicated that the training material we have seen appears to hold ACAS systems and the use of transponders as an airspace design mitigation in Class E airspace. On further examination of the material, it would appear that there is no DIRECT statement to that effect, nor direct linkage – if we have misinterpreted the material, we apologize to the respondent and affected parties. We have noted, however, the consistent reference to the carriage and operation of transponders, and the illustrations of TCAS operation, and can only draw a strong inference that the intent is that aircraft carrying ACAS type equipment will be afforded some additional layer of protection in Class E airspace.
Let us be perfectly clear. There is no requirement in the ICAO airspace classification system for the carriage and operation of transponders, nor the use of ACAS type systems. The classifications stand or fall on their own merit. As we have pointed out previously, the operation of transponders within Class E airspace is only of use as a design tool where there is secondary radar coverage – to allow enhanced provision of traffic information by a third party. Transponder carriage and operation outside of radar coverage cannot possibly be used as a tool to enhance airspace design. Some States – such as the United States of America, and certain European States - have recognised that they have substantial secondary radar coverage, and have been able to factor that coverage, and widespread transponder carriage, in the assessment of risk, allowing Class E airspace to be used more widely.
We agree totally that it is of exceptional benefit, overall, to aviation safety, for aircraft to carry and operate transponders – but this is not to be used as a factor in the design of airspace, and may better have been omitted from your airspace debates, and implemented as a separate safety initiative.
Clearly, there is theoretically little or no difference in the levels of service provided between IFR aircraft operating in Airspace Classes A, B, C, D or E. We say theoretical, because in practice, there is a higher potential for tactical – rather than planned - response by IFR flights in relation to VFR flights in Class E airspace, which may impact the ability to offer, or the effectiveness of offered, separation services to IFR flights.
Where the differences occur, of course, is the interaction between IFR and VFR flights. By that, we mean that an IFR aircraft may require services more urgently [i.e., tactically rather than in a planned fashion] in Class E airspace because of the proximity of VFR flights, or may not be able to comply with a planned ATC instruction. This adds a level of complexity to the model – for both pilots and providers of services – something that needs to be factored in the holistic airspace design. That is not to say Class E should not be used – far from it – but it must be appreciated that Class E operates in a fundamentally different way than Classes A through D.
In any given volume of airspace, with the same number of IFR and VFR flights, the level of risk must increase when Class C airspace is changed to Class E [or Class D, or Class F or Class G for that matter]. Equally, a change upwards in classification, from Class C to Class B or Class A, for a given volume of airspace, with the same number of IFR and VFR flights, the level of risk is decreased.
As we have indicated before, the intent of the airspace classification system was to provide a menu of services whereby the levels of risk to all aircraft – but in particular IFR flights – could be maintained within an acceptable band – but without unduly restricting the amenity of VFR flights, and adding unnecessary expense to operators.
We do not dispute the fact that in many instances – and this has occurred around the globe – that the initial transition to the airspace classification system was done without conducting a risk analysis – or identifying what risks were being managed – before the “label” was assigned. This could, of course, result in levels of service that far exceed those truly required in a given volume of airspace. We suspect that this has happened in your country, as it has happened in others.
It will prove almost impossible to develop an airspace model where the level of risk to any particular aircraft or group of aircraft – IFR or VFR – is uniform. As we have mentioned in previous posts, having determined the risk levels, and appropriate classifications, you will need to “smooth” the model, by changing some classifications for the sake of simplicity and uniformity.
Now we need to clarify a point made direct to us by a respondent. We have indicated that the training material we have seen appears to hold ACAS systems and the use of transponders as an airspace design mitigation in Class E airspace. On further examination of the material, it would appear that there is no DIRECT statement to that effect, nor direct linkage – if we have misinterpreted the material, we apologize to the respondent and affected parties. We have noted, however, the consistent reference to the carriage and operation of transponders, and the illustrations of TCAS operation, and can only draw a strong inference that the intent is that aircraft carrying ACAS type equipment will be afforded some additional layer of protection in Class E airspace.
Let us be perfectly clear. There is no requirement in the ICAO airspace classification system for the carriage and operation of transponders, nor the use of ACAS type systems. The classifications stand or fall on their own merit. As we have pointed out previously, the operation of transponders within Class E airspace is only of use as a design tool where there is secondary radar coverage – to allow enhanced provision of traffic information by a third party. Transponder carriage and operation outside of radar coverage cannot possibly be used as a tool to enhance airspace design. Some States – such as the United States of America, and certain European States - have recognised that they have substantial secondary radar coverage, and have been able to factor that coverage, and widespread transponder carriage, in the assessment of risk, allowing Class E airspace to be used more widely.
We agree totally that it is of exceptional benefit, overall, to aviation safety, for aircraft to carry and operate transponders – but this is not to be used as a factor in the design of airspace, and may better have been omitted from your airspace debates, and implemented as a separate safety initiative.
V of R:
Arrhh, yes. Had TCAS not been incorporated as a basic mitigator, we would not have AusNAS, at all. Even the fanatics (Dick Smith, Mike Smith, the two bills and boyd et al) would have conceded that. And therein is the problem.
We agree totally that it is of exceptional benefit, overall, to aviation safety, for aircraft to carry and operate transponders – but this is not to be used as a factor in the design of airspace, and may better have been omitted from your airspace debates, and implemented as a separate safety initiative.
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SAFETY – AT WHAT COST?
Safety is complex - difficult in advance - so easy in hindsight!
We have been pointed to references in parallel posts about affordable safety. In the determination of appropriate airspace design, considerable weight needs to be placed on the cost, versus benefit, of any particular change. We note, with interest, that in most cases, the cost benefit analysis associated with the removal or reduction of service is substantially different from that where an increase in service is proposed. A good – and freely available – example of this is the United States of America Federal Aviation Administration’s document on tower establishment and discontinuance, where the presence of an existing service [a tower] makes it more difficult to discontinue or reduce a service.
It cannot be denied that whilst safety is an absolute imperative in aviation – it is not the only imperative, and needs to be balanced against a range of factors. Safety costs – and it needs to be paid for, most often by the users of the amenity themselves. So the notion of attributing resources to those areas where safety is most benefited is certainly supported. We must point out that in many legal cases, judges have found, in relation to safety, that where a safety action could have been undertaken at little or no cost, then such action should have been taken. Unfortunately, most of these observations are made post-factum. Many things are inexpensive with the benefit of hindsight.
We must also state that whilst attribution of safety resource for the protection of many should always be an objective, this should not come at the expense of those who, whilst choosing a knowingly or apparently dangerous activity, do not engage in that activity dangerously. By this we mean that the general aviation community does not believe that the activity it undertakes is inherently dangerous – no more than a motorist taking a “Sunday drive”. The belief by the general public that an activity is inherently less safe than any other activity should not be a reason for deliberately increasing levels of risk to that part of the aviation community. In short, achieving safety for the majority, at the inappropriate expense of a minority, should not be an airspace design outcome.
We have attached two relevant extracts, which may be of some interest. The first is an extract from “1997 WHITE HOUSE COMMSSION ON AVIATION SAFETY AND SECURITY THE DOT STATUS REPORT”
“...The Department of Transportation recognizes that in conducting benefit-cost analysis in aviation safety and security rulemakings, quite often there are both tangible and intangible benefits of a rule. It is also necessary to assess risks and examine potential mitigating measures. A key is not to wait for accidents to happen but to identify high-risk potential causes and act to address them before an accident occurs. The Department recognizes the importance of sound economic analysis when it comes to rulemakings, and that such an analysis includes taking into account both tangible and intangible benefits. Accordingly, the Department has instituted into its rulemaking practices a policy to ensure that costs alone are not dispositive in the rulemaking process....”
In responding to the challenge, the FAA sated: “...the Commission recommended that cost not always be the determining factor or basis for deciding whether to put new aviation safety and security rules into effect. Specifically, the Commission notes that the potential reduction in the fatal accident rate merits a careful weighing of the options for improving safety in terms of the benefits that go beyond those traditionally considered in benefit-cost analyses. However, we also believe that it is important to recognize that the recommendation (1) represents a significant departure from traditional processes, (2) could result in significant cost increases for relatively modest increases in the safety margin, and (3) could rest on a limited empirical justification. In effect, this recommendation may increase the number of instances in which the primary factor determining whether or not to go forward with a safety or security improvement is what might be referred to as a public policy imperative rather than the result of a benefit-cost analysis...”.
The second extract is from a New Zealand review report on the term “safety at reasonable cost”, which is a statement contained in New Zealand aviation legislation.
The Civil Aviation Act describes the Authority functions as "activities which promote safety in civil aviation at a reasonable cost". Reasonable cost is defined in the Civil Aviation Act 1990 as 'where the value of the cost to the nation is exceeded by the resulting benefit to the nation.' The provisions in the Act relating to "safety at reasonable cost", stem directly from the following Swedavia - McGregor recommendations:
"...The aviation safety goal is: that the civil aviation system takes all measures that would improve safety at reasonable cost, subject to the State meeting its minimum obligations under ICAO. Reasonable cost is interpreted as meaning that the cost to the nation is exceeded by the benefits to the nation. The aviation safety regulatory body should stop striving for improvement in safety at the point where the value of the next increment of safety is outweighed by the cost of achieving it...".
Implicit in these recommendations is a need to evaluate benefits and costs. In this context, Swedavia - McGregor recommended that:
"...Cost-benefit analysis should, whenever practicable, be a mandatory tool in the rulemaking process for discretionary areas...".
With respect to making of rules, the Act requires that the Minister or Director
"shall have regard to, and shall give such weight as he or she considers appropriate in each case to -
f.The costs of implementing aviation safety and security."
The Review observes that the CAA, in principle, applies the notion of safety at reasonable cost in assessing what it should do to achieve safety outcomes. CAA management understand, and are committed to, the concept of safety at reasonable cost. The CAA adopts a pragmatic approach. The CAA assesses suitability of the conduct of benefit/ cost analysis (BCA) where appropriate, and at other times aims to achieve safety at reasonable cost through the application of proven international best practice for safety standards and activities. The Review has referred already to the consultation processes in place to ensure that the views of industry participants are considered before decisions are made, particularly on Rules development.
Notwithstanding the above comments, the Review concludes that there is room for some improvement in the CAA's application of benefit/ cost analysis, particularly with regards to the conduct of benefit/ cost analysis during the development of Rules, and for other initiatives where this could be considered appropriate.
Where activities are mandatory, the issue becomes more one of cost effectiveness, that is, the achievement of outcomes at least cost. A full assessment of the management of CAA resources and costs is outside the scope of the current Review. However, some suggestions are made for some areas where the CAA might enhance its allocation of resources (see below).
While the Civil Aviation Act 1990 clearly refers to 'safety at reasonable cost', there is no requirement in the Act to complete a benefit/cost analysis. Even the development of cost data appears to be discretionary. Furthermore, it is unclear from the Act as to whether "the value of the cost to the nation is exceeded by the value of the resulting benefit to the nation" applies to the civil aviation regulatory function as a whole or to specific rules and activities, or both. There are both positive and negative aspects of conducting a benefit/ cost analysis.
On the positive side, a thorough benefit/ cost analysis requires the implications of a proposed rule to be assessed. It provides the decision maker with an objective tool. Once completed, it also provides a transparent basis for decision-making.
On the other hand, benefit/ cost analysis can be time-consuming and costly to undertake. A complex rule, for example, could involve several months' work and cost in the hundreds of thousands of dollars. A benefit/ cost analysis for a safety Rule also can generate high emotion, as it requires a value to be set for human life. The value for human life in aviation terms has not yet been established, and there are grounds for suggesting that the value of life used by other transport safety regulators (in particular Land Transport Safety Authority) may not be appropriate in the aviation sector.
The aviation community is very divided on the need for benefit/ cost analysis to be undertaken. Some claim that a benefit/ cost analysis should never be done, while others argue that a study should be done for every rule proposal. Most take a pragmatic middle-of-the road approach.
The Review supports a pragmatic approach to the use of formal benefit/ cost analysis. Major Rule changes that are expected to involve significant compliance costs should be subject to formal benefit/ cost analysis, to ensure that the requirement for benefits to exceed costs has been tested. However, minor changes may well not warrant a full analysis if the costs of undertaking the analysis would outweigh the benefits of the change or if the benefits of the change are readily apparent.
In other instances, if an ICAO standard leads to a rule change, under normal circumstances it would not be cost-effective to undertake a costly analysis given the provisions in the Act promoting harmonisation with ICAO. That said, however, it may be advisable for a benefit/ cost analysis to be undertaken for specific projects that result from a rule change, in order to determine options for compliance. An example of this is runway end safety area standards.
In order to determine the extent of analysis, including formal benefit/ cost analysis, that is required to evaluate a Rule change, an open and transparent rulemaking process is required that allows for discussion by interested parties. Recommendations can then be made to the Director who would then decide the scope of benefit/ cost analysis required.
Cost estimates for a new or changed rule are generally much easier than quantifying safety benefits. Therefore, it would be advisable to determine costs for all new rules. Industry can generally determine implications for respective sectors, whereas the CAA can complete cost estimates for regulatory implications.
We have been pointed to references in parallel posts about affordable safety. In the determination of appropriate airspace design, considerable weight needs to be placed on the cost, versus benefit, of any particular change. We note, with interest, that in most cases, the cost benefit analysis associated with the removal or reduction of service is substantially different from that where an increase in service is proposed. A good – and freely available – example of this is the United States of America Federal Aviation Administration’s document on tower establishment and discontinuance, where the presence of an existing service [a tower] makes it more difficult to discontinue or reduce a service.
It cannot be denied that whilst safety is an absolute imperative in aviation – it is not the only imperative, and needs to be balanced against a range of factors. Safety costs – and it needs to be paid for, most often by the users of the amenity themselves. So the notion of attributing resources to those areas where safety is most benefited is certainly supported. We must point out that in many legal cases, judges have found, in relation to safety, that where a safety action could have been undertaken at little or no cost, then such action should have been taken. Unfortunately, most of these observations are made post-factum. Many things are inexpensive with the benefit of hindsight.
We must also state that whilst attribution of safety resource for the protection of many should always be an objective, this should not come at the expense of those who, whilst choosing a knowingly or apparently dangerous activity, do not engage in that activity dangerously. By this we mean that the general aviation community does not believe that the activity it undertakes is inherently dangerous – no more than a motorist taking a “Sunday drive”. The belief by the general public that an activity is inherently less safe than any other activity should not be a reason for deliberately increasing levels of risk to that part of the aviation community. In short, achieving safety for the majority, at the inappropriate expense of a minority, should not be an airspace design outcome.
We have attached two relevant extracts, which may be of some interest. The first is an extract from “1997 WHITE HOUSE COMMSSION ON AVIATION SAFETY AND SECURITY THE DOT STATUS REPORT”
“...The Department of Transportation recognizes that in conducting benefit-cost analysis in aviation safety and security rulemakings, quite often there are both tangible and intangible benefits of a rule. It is also necessary to assess risks and examine potential mitigating measures. A key is not to wait for accidents to happen but to identify high-risk potential causes and act to address them before an accident occurs. The Department recognizes the importance of sound economic analysis when it comes to rulemakings, and that such an analysis includes taking into account both tangible and intangible benefits. Accordingly, the Department has instituted into its rulemaking practices a policy to ensure that costs alone are not dispositive in the rulemaking process....”
In responding to the challenge, the FAA sated: “...the Commission recommended that cost not always be the determining factor or basis for deciding whether to put new aviation safety and security rules into effect. Specifically, the Commission notes that the potential reduction in the fatal accident rate merits a careful weighing of the options for improving safety in terms of the benefits that go beyond those traditionally considered in benefit-cost analyses. However, we also believe that it is important to recognize that the recommendation (1) represents a significant departure from traditional processes, (2) could result in significant cost increases for relatively modest increases in the safety margin, and (3) could rest on a limited empirical justification. In effect, this recommendation may increase the number of instances in which the primary factor determining whether or not to go forward with a safety or security improvement is what might be referred to as a public policy imperative rather than the result of a benefit-cost analysis...”.
The second extract is from a New Zealand review report on the term “safety at reasonable cost”, which is a statement contained in New Zealand aviation legislation.
The Civil Aviation Act describes the Authority functions as "activities which promote safety in civil aviation at a reasonable cost". Reasonable cost is defined in the Civil Aviation Act 1990 as 'where the value of the cost to the nation is exceeded by the resulting benefit to the nation.' The provisions in the Act relating to "safety at reasonable cost", stem directly from the following Swedavia - McGregor recommendations:
"...The aviation safety goal is: that the civil aviation system takes all measures that would improve safety at reasonable cost, subject to the State meeting its minimum obligations under ICAO. Reasonable cost is interpreted as meaning that the cost to the nation is exceeded by the benefits to the nation. The aviation safety regulatory body should stop striving for improvement in safety at the point where the value of the next increment of safety is outweighed by the cost of achieving it...".
Implicit in these recommendations is a need to evaluate benefits and costs. In this context, Swedavia - McGregor recommended that:
"...Cost-benefit analysis should, whenever practicable, be a mandatory tool in the rulemaking process for discretionary areas...".
With respect to making of rules, the Act requires that the Minister or Director
"shall have regard to, and shall give such weight as he or she considers appropriate in each case to -
f.The costs of implementing aviation safety and security."
The Review observes that the CAA, in principle, applies the notion of safety at reasonable cost in assessing what it should do to achieve safety outcomes. CAA management understand, and are committed to, the concept of safety at reasonable cost. The CAA adopts a pragmatic approach. The CAA assesses suitability of the conduct of benefit/ cost analysis (BCA) where appropriate, and at other times aims to achieve safety at reasonable cost through the application of proven international best practice for safety standards and activities. The Review has referred already to the consultation processes in place to ensure that the views of industry participants are considered before decisions are made, particularly on Rules development.
Notwithstanding the above comments, the Review concludes that there is room for some improvement in the CAA's application of benefit/ cost analysis, particularly with regards to the conduct of benefit/ cost analysis during the development of Rules, and for other initiatives where this could be considered appropriate.
Where activities are mandatory, the issue becomes more one of cost effectiveness, that is, the achievement of outcomes at least cost. A full assessment of the management of CAA resources and costs is outside the scope of the current Review. However, some suggestions are made for some areas where the CAA might enhance its allocation of resources (see below).
While the Civil Aviation Act 1990 clearly refers to 'safety at reasonable cost', there is no requirement in the Act to complete a benefit/cost analysis. Even the development of cost data appears to be discretionary. Furthermore, it is unclear from the Act as to whether "the value of the cost to the nation is exceeded by the value of the resulting benefit to the nation" applies to the civil aviation regulatory function as a whole or to specific rules and activities, or both. There are both positive and negative aspects of conducting a benefit/ cost analysis.
On the positive side, a thorough benefit/ cost analysis requires the implications of a proposed rule to be assessed. It provides the decision maker with an objective tool. Once completed, it also provides a transparent basis for decision-making.
On the other hand, benefit/ cost analysis can be time-consuming and costly to undertake. A complex rule, for example, could involve several months' work and cost in the hundreds of thousands of dollars. A benefit/ cost analysis for a safety Rule also can generate high emotion, as it requires a value to be set for human life. The value for human life in aviation terms has not yet been established, and there are grounds for suggesting that the value of life used by other transport safety regulators (in particular Land Transport Safety Authority) may not be appropriate in the aviation sector.
The aviation community is very divided on the need for benefit/ cost analysis to be undertaken. Some claim that a benefit/ cost analysis should never be done, while others argue that a study should be done for every rule proposal. Most take a pragmatic middle-of-the road approach.
The Review supports a pragmatic approach to the use of formal benefit/ cost analysis. Major Rule changes that are expected to involve significant compliance costs should be subject to formal benefit/ cost analysis, to ensure that the requirement for benefits to exceed costs has been tested. However, minor changes may well not warrant a full analysis if the costs of undertaking the analysis would outweigh the benefits of the change or if the benefits of the change are readily apparent.
In other instances, if an ICAO standard leads to a rule change, under normal circumstances it would not be cost-effective to undertake a costly analysis given the provisions in the Act promoting harmonisation with ICAO. That said, however, it may be advisable for a benefit/ cost analysis to be undertaken for specific projects that result from a rule change, in order to determine options for compliance. An example of this is runway end safety area standards.
In order to determine the extent of analysis, including formal benefit/ cost analysis, that is required to evaluate a Rule change, an open and transparent rulemaking process is required that allows for discussion by interested parties. Recommendations can then be made to the Director who would then decide the scope of benefit/ cost analysis required.
Cost estimates for a new or changed rule are generally much easier than quantifying safety benefits. Therefore, it would be advisable to determine costs for all new rules. Industry can generally determine implications for respective sectors, whereas the CAA can complete cost estimates for regulatory implications.
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Industry can generally determine implications for respective sectors, whereas the CAA can complete cost estimates for regulatory implications.
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Further Information on the Use of ACAS Type Systems in Airspace Design
We have noted responses – both on this site, and direct to us – regarding the use of airborne collision avoidance systems as airspace design mitigators, and have also been pointed to certain web-sites in your country – most notably a site hosted by your Department of Transport and Regional Services, for a project known as the National Airspace System. We were surprised to find the following relating to airspace design principles in documents on that site:
“…The following document was finalised on 14 December 2001 and details the original NAS Australia proposal. It was part of the report prepared by the ARG for the Minister for Transport and Regional Services in March 2002, which was considered and agreed to by the Government on 13 May 2002:
Airspace Architecture Design Principles [dated 14 December 2001]
The following principles provide the high level framework for the allocation of airspace classifications to Australian domestic and international airspace:
Situational awareness will be enhanced by third party traffic advice, by pilot reports or by electronic mean (a footnote explains that electronic means includes TCAS and ADS-B/CDTI);
…
Any safety analysis shall employ a methodology of comparative study of proven systems. Where this is not feasible, an ALARP/constrained cost – benefit methodology will be used;
…
In order to mitigate the risk of systemic (human) failure, airspace and procedures design must remain simple and logical, and must be supported by comprehensive training and education programmes.
…”
We have reviewed a number of ICAO documents, and provide the following extracts for clarification:
ICAO ANNEX 11:
SECTION 2.4: DETERMINATION OF THE NEED FOR AIR TRAFFIC SERVICES
2.4.1 The need for the provision of air traffic services shall be determined by consideration of the following:
a. the types of air traffic involved;
b. the density of air traffic;
c. the meteorological conditions;
d. such other factors as may be relevant.
Note:- due to the number of elements involved, it has not been possible to develop specific data to determine the need for air traffic services in a given area or at a given location. For example:
a. a mixture of types of aircraft of varying speed (conventional jet, etc) might necessitate the provision of air traffic services, whereas a relatively greater density of traffic where only one type of operation is involved would not;
b. meteorological conditions might have considerable effect in areas where there is a constant flow of air traffic (e.g., scheduled traffic), whereas similar or worse meteorological conditions might be relatively unimportant in an area where air traffic would be discontinued is such conditions (e.g., local VFR flights);
c. open stretches of water, mountainous, uninhabited or desert areas might necessitate the provision of air traffic services even though the frequency of operations is extremely low.
2.4.2 The carriage of airborne collision avoidance systems (ACAS) by aircraft in a given area shall not be a factor in determining the need for air traffic services in that area.
The words in paragraphs 2.4.1 and 2.4.2 of Annex 11 are “Standards” – standards employ the operative verb “shall”. A “standard” is defined by ICAO as “… any specification for physical characteristics, configuration, materiel, performance, personnel or procedure, the uniform application of which is recognised as necessary for the safety or regularity of international air navigation in accordance with the Convention; in the event of impossibility of compliance, notification to the Council is compulsory under Article 38.
ICAO DOCUMENT 9689 - MANUAL ON AIRSPACE PLANNING METHODOLOGY FOR THE DETERMINATION OF SEPARATION MINIMA
Aircraft equipped with airborne collision avoidance systems (ACAS)
3.8 It should be noted that, in accordance with the guidance given in Annex 11, the carriage of ACAS by aircraft within a region should not be used to justify a reduced separation minimum. However, the presence of such systems may be relevant when contemplating the application of reduced separations, as changes to the ACAS systems may be required in order to avoid an unacceptable rate of false alerts.
Whilst the use of ACAS systems as a design mitigator may be ambiguous in training material being distributed to pilots, there is clear reference to its use as a design tool in the design principles document. As we have stated on a number of previous occasions, under rules established by the International Civil Aviation Organization, such systems cannot be factored when designing airspace.
“…The following document was finalised on 14 December 2001 and details the original NAS Australia proposal. It was part of the report prepared by the ARG for the Minister for Transport and Regional Services in March 2002, which was considered and agreed to by the Government on 13 May 2002:
Airspace Architecture Design Principles [dated 14 December 2001]
The following principles provide the high level framework for the allocation of airspace classifications to Australian domestic and international airspace:
Situational awareness will be enhanced by third party traffic advice, by pilot reports or by electronic mean (a footnote explains that electronic means includes TCAS and ADS-B/CDTI);
…
Any safety analysis shall employ a methodology of comparative study of proven systems. Where this is not feasible, an ALARP/constrained cost – benefit methodology will be used;
…
In order to mitigate the risk of systemic (human) failure, airspace and procedures design must remain simple and logical, and must be supported by comprehensive training and education programmes.
…”
We have reviewed a number of ICAO documents, and provide the following extracts for clarification:
ICAO ANNEX 11:
SECTION 2.4: DETERMINATION OF THE NEED FOR AIR TRAFFIC SERVICES
2.4.1 The need for the provision of air traffic services shall be determined by consideration of the following:
a. the types of air traffic involved;
b. the density of air traffic;
c. the meteorological conditions;
d. such other factors as may be relevant.
Note:- due to the number of elements involved, it has not been possible to develop specific data to determine the need for air traffic services in a given area or at a given location. For example:
a. a mixture of types of aircraft of varying speed (conventional jet, etc) might necessitate the provision of air traffic services, whereas a relatively greater density of traffic where only one type of operation is involved would not;
b. meteorological conditions might have considerable effect in areas where there is a constant flow of air traffic (e.g., scheduled traffic), whereas similar or worse meteorological conditions might be relatively unimportant in an area where air traffic would be discontinued is such conditions (e.g., local VFR flights);
c. open stretches of water, mountainous, uninhabited or desert areas might necessitate the provision of air traffic services even though the frequency of operations is extremely low.
2.4.2 The carriage of airborne collision avoidance systems (ACAS) by aircraft in a given area shall not be a factor in determining the need for air traffic services in that area.
The words in paragraphs 2.4.1 and 2.4.2 of Annex 11 are “Standards” – standards employ the operative verb “shall”. A “standard” is defined by ICAO as “… any specification for physical characteristics, configuration, materiel, performance, personnel or procedure, the uniform application of which is recognised as necessary for the safety or regularity of international air navigation in accordance with the Convention; in the event of impossibility of compliance, notification to the Council is compulsory under Article 38.
ICAO DOCUMENT 9689 - MANUAL ON AIRSPACE PLANNING METHODOLOGY FOR THE DETERMINATION OF SEPARATION MINIMA
Aircraft equipped with airborne collision avoidance systems (ACAS)
3.8 It should be noted that, in accordance with the guidance given in Annex 11, the carriage of ACAS by aircraft within a region should not be used to justify a reduced separation minimum. However, the presence of such systems may be relevant when contemplating the application of reduced separations, as changes to the ACAS systems may be required in order to avoid an unacceptable rate of false alerts.
Whilst the use of ACAS systems as a design mitigator may be ambiguous in training material being distributed to pilots, there is clear reference to its use as a design tool in the design principles document. As we have stated on a number of previous occasions, under rules established by the International Civil Aviation Organization, such systems cannot be factored when designing airspace.
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The Use of Comparative Analysis as an Airspace Design Tool
Members of our group have been engaged in airspace design work around the globe for many years, and whilst not experts, we have a reasonable amount of expertise in this area. Airspace design is an exceptionally complex discipline, and requires very careful analysis of all available data and information to form correct and sustainable technical outputs, and careful understanding of the operating environment in order to develop a socially and politically acceptable output.
In the course of reviewing material associated with our previous post to this site, we came across puzzling statements relating to the use of “reference systems” in airspace design. In the document on the Department of Transport and Regional Services website for the National Airspace System, entitled Airspace Architecture Design Principles (dated 14 December 2001), we found the following two statements:
“….The following principles provide the high level framework for the allocation of airspace classifications to Australian domestic and international airspace:
….Any safety analysis shall employ a methodology of comparative study of proven systems. Where this is not feasible, an ALARP/constrained cost – benefit methodology will be used…”.
And within the same document:
Safety Analysis
3.1 Methodology
ICAO provides two methodologies for “determining whether the system is acceptably safe”:
a. comparison to a reference system, and
b. evaluation of system risks against a threshold.
Comparison with a reference system is a relative method, i.e. all the relative characteristics of the proposed system are compared with the corresponding characteristics of a reference system, which has been judged to be safe. Provided that the proposed system can be demonstrated to be the same or better than the reference system in all safety aspects, then it may be assumed also to be safe…”
As the NAS draws on international best practice and the proven ATM system of North America, process a. above is the appropriate methodology.
3.2 Application
This “comparison with a reference system” process will be applied as follows:
REMOVAL OF DIRECTED FULL SAR TRAFFIC SERVICE IN CLASS G AIRSPACE. Primary reference: The existing Australian Class G system in the Northern Territory where IFR now operate on a self-announce basis in large CTAFs to 10,000’. Supportive reference: The USA FAA system where Class G extends to FL145 in low density traffic areas.
CLASS G TERMINAL AREAS. Primary reference: The existing Australian Class G system. Supportive reference: The Canadian Class G system in terminal areas.
CLASS E RADAR AND NON-RADAR ENROUTE AIRSPACE. Primary reference: The USA FAA system. Supportive reference: The existing Australian Class E airspace.
CLASS E RADAR AND NON-RADAR TERMINAL AIRSPACE: Primary reference: The USA FAA system. Supportive reference: The Canadian system.
CHANGE MBZ PROCEDURES TO CTAF/UNICOMS. Primary reference: The reference will be the USA FAA CTAF/UNICOM system. Supportive reference: The existing Australian CTAF system as used by scheduled services.
We believe that the basis for these statements in relation to ICAO and reference systems lies in out-of-context references to ICAO Document 9689 - Manual on Airspace Planning Methodology for the Determination of Separation Minima. That document was SPECIFICALLY DEVELOPED FOR USE IN THE DETERMINATION OF SEPARATION MINIMA IN CONTROLLED AIRSPACE, though it does also contain references to risk assessment methodologies outside of controlled airspace.
The NAS design principles document makes an assertion that “ICAO provides two methodologies for “…determining whether the system is acceptably safe - comparison to a reference system, and evaluation of system risks against a threshold…”. This is subtly out of context. ICAO Document 9689 actually states:
“….5.1 The safety of a system depends on a number of characteristics of the airspace (see chapter 3). When the relevant characteristics have been identified and quantified, there are two basic methods for determining whether the system is acceptably safe – comparison with a reference system; and evaluation of a system risk against a threshold.
5.2 Comparison with a reference system is a “relative” method, i.e., all the relevant characteristics of the proposed system are compared with the corresponding characteristics of a reference system which has been judged to be safe. Provided that the proposed system can be demonstrated to be similar to or better than the reference system in all safety-related aspects, then it may be assumed to be safe….”
Chapter 6 of ICAO Document 9689 specifically deals with the issue of comparison with a reference system. Paragraph 6.3 and 6.4 state:
“whatever reference system is chosen, it must bear a sufficiently close resemblance to the proposed system for any comparison with regard to safety to be valid. The levels of air traffic service provided in the reference and proposed airspaces, as defined by the ICAO airspace classifications, should be examined. The air traffic service in the proposed system should provide at least the same level of service as the reference system.
The minimum requirements for a reference system to be considered similar to a proposed system are:
a. Separation minima should not be less in the proposed system than in the reference system;
b. proposed means of communication and surveillance must be no worse in terms of accuracy, reliability, integrity and availability than those of the reference system;
c. frequency and duration of the application of minimum separation between aircraft must not be greater in the proposed system than in the reference system; and
d. navigation performance [typical and non-typical] of the population of aircraft in the proposed system should be no worse in its effect on collision risk, in any dimension, than that of aircraft in the reference system”.
Paragraph 6.8 then states:
“Once a reference system has been chosen, the airspace planner must perform the following steps to evaluate the relative safety of the two systems:
1. describe in detail the differences and similarities between the two systems. This must be done for all of the criteria in Chapter 3 [refer extract below];
2. For each criterion, assess how any differences between the systems would affect the risk. This can be done using mathematical techniques and/or using operational judgment. However, care must be taken to identify situations where the effect on collision risk is counter-intuitive. For example, an increase in lateral navigation accuracy, whilst decreasing collision risk in the lateral dimension, could actually increase the risk of a collision in the longitudinal or vertical dimensions. Furthermore, where risk is dominated by the occurrence of large operational errors, an increase in lateral navigation accuracy may even increase the lateral collision risk;
3. For each criterion, ensure that the proposed system is at least as safe as the reference system. Alternatively, a trade-off between factors, which are worse, and those which are better than the reference system, may be possible.
Chapter 3 of ICAO Document 9689 states, verbatim:
CHAPTER 3
DESCRIPTION OF THE CURRENT AIRSPACE AND THE CNS/ATM SYSTEMS
DETERMINING SEPARATION MINIMA
3.1 In determining appropriate separation minima, the airspace planner must have a thorough knowledge of the existing airspace, the CNS/ATM capabilities and the airspace characteristics, which may influence the safe separation minima. There are a number of factors that may influence the separation minima and these include:
3.2 Airspace structure:
a) route structure, e.g. the use of parallel or non-parallel ATS routes and whether they are bi-directional or unidirectional;
b) existing separation minima and how often values close to the separation minima are used in practice;
c) complexity of the airspace, including inter alia:
1) traffic demand pattern,
2) numbers and locations of crossing tracks,
3) amount of traffic operating on opposite direction tracks,
4) amount of traffic which is either climbing or descending,
5) nature of the aircraft population, i.e. the diversity of traffic with respect to aircraft performance and equipage (e.g. mix of various speeds, climb performance, desired optimal flight levels),
6) peak and average traffic demands versus system capacity,
7) runway capacities and the limitations of associated ground services,
8) any adjoining special-use airspace, airspace usage and types of activities including the civil/military mix, and
9) regional meteorological conditions (e.g. the prevalence of convective storms etc), and
d) designated airspace classifications.
3.3 Communication capability:
a) direct controller/pilot voice communication (VHF/HF/SATCOM);
b) indirect controller/pilot voice communication (HF);
c) controller/pilot data link communication (CPDLC);
d) controller/controller voice and automated data link communication, both inter and intra ATS unit(s);
e)data link between ground ATC automation systems and aircraft flight management computers; and
f)system availability, reliability and capacity;
3.4 Surveillance capability:
a) procedural dependent surveillance:
1)content of pilot position reports, and
2)reporting intervals;
b) automatic dependent surveillance (ADS):
1) basic update rate,
2) display accuracy,
3) ADS contract (e.g. events triggering increased reporting rate),
4) sensor accuracy,
5) system reliability, and
6) end-to-end communications time capabilities; and
c) independent surveillance (radar):
1) type of sensor (primary or secondary),
2)coverage area,
3)processing and associated delays,
4)accuracy of measured position after processing,
5)update rate,
6)display accuracy, and
7)system reliability.
3.5 Aircraft navigation performance:
a)required navigation performance (RNP);
b)typical and non-typical performance (e.g. MASPS/MOPS), (RTCA SC181 documents refer); and
c)time-keeping accuracy.
3.6 Flow management capability (ability to control traffic input to ATC):
a) strategic air traffic flow management;
b) tactical air traffic flow management;
c) ad hoc ATC “in trail” restrictions or enhancements; and
d) procedural restrictions (e.g. through local operating procedures).
3.7 Air traffic management tools to reduce controller workload or improve controller intervention capability:
a)automated controller planning tools, including conflict prediction and resolution;
b)controller displays; and
c)out-of-conformance alerts (3-D) (i.e. automatic systems which alert ATC to any deviation of an aircraft from its nominal path).
The Department of Transport and Regional Services web-site makes the following statement in relation to the design principles document:
“…The following document was finalised on 14 December 2001 and details the original NAS Australia proposal. It was part of the report prepared by the ARG for the Minister for Transport and Regional Services in March 2002, which was considered and agreed to by the Government on 13 May 2002…”
We have not seen any evidence in publicly available material that any such detailed comparative analysis had been carried out in providing advice to your airspace administrators.
If this is the case, then it is entirely possible that misleading or incorrect information may have been provided to your Minister for Transport and Regional Services, and that may have prompted incorrect decision making processes.
In the course of reviewing material associated with our previous post to this site, we came across puzzling statements relating to the use of “reference systems” in airspace design. In the document on the Department of Transport and Regional Services website for the National Airspace System, entitled Airspace Architecture Design Principles (dated 14 December 2001), we found the following two statements:
“….The following principles provide the high level framework for the allocation of airspace classifications to Australian domestic and international airspace:
….Any safety analysis shall employ a methodology of comparative study of proven systems. Where this is not feasible, an ALARP/constrained cost – benefit methodology will be used…”.
And within the same document:
Safety Analysis
3.1 Methodology
ICAO provides two methodologies for “determining whether the system is acceptably safe”:
a. comparison to a reference system, and
b. evaluation of system risks against a threshold.
Comparison with a reference system is a relative method, i.e. all the relative characteristics of the proposed system are compared with the corresponding characteristics of a reference system, which has been judged to be safe. Provided that the proposed system can be demonstrated to be the same or better than the reference system in all safety aspects, then it may be assumed also to be safe…”
As the NAS draws on international best practice and the proven ATM system of North America, process a. above is the appropriate methodology.
3.2 Application
This “comparison with a reference system” process will be applied as follows:
REMOVAL OF DIRECTED FULL SAR TRAFFIC SERVICE IN CLASS G AIRSPACE. Primary reference: The existing Australian Class G system in the Northern Territory where IFR now operate on a self-announce basis in large CTAFs to 10,000’. Supportive reference: The USA FAA system where Class G extends to FL145 in low density traffic areas.
CLASS G TERMINAL AREAS. Primary reference: The existing Australian Class G system. Supportive reference: The Canadian Class G system in terminal areas.
CLASS E RADAR AND NON-RADAR ENROUTE AIRSPACE. Primary reference: The USA FAA system. Supportive reference: The existing Australian Class E airspace.
CLASS E RADAR AND NON-RADAR TERMINAL AIRSPACE: Primary reference: The USA FAA system. Supportive reference: The Canadian system.
CHANGE MBZ PROCEDURES TO CTAF/UNICOMS. Primary reference: The reference will be the USA FAA CTAF/UNICOM system. Supportive reference: The existing Australian CTAF system as used by scheduled services.
We believe that the basis for these statements in relation to ICAO and reference systems lies in out-of-context references to ICAO Document 9689 - Manual on Airspace Planning Methodology for the Determination of Separation Minima. That document was SPECIFICALLY DEVELOPED FOR USE IN THE DETERMINATION OF SEPARATION MINIMA IN CONTROLLED AIRSPACE, though it does also contain references to risk assessment methodologies outside of controlled airspace.
The NAS design principles document makes an assertion that “ICAO provides two methodologies for “…determining whether the system is acceptably safe - comparison to a reference system, and evaluation of system risks against a threshold…”. This is subtly out of context. ICAO Document 9689 actually states:
“….5.1 The safety of a system depends on a number of characteristics of the airspace (see chapter 3). When the relevant characteristics have been identified and quantified, there are two basic methods for determining whether the system is acceptably safe – comparison with a reference system; and evaluation of a system risk against a threshold.
5.2 Comparison with a reference system is a “relative” method, i.e., all the relevant characteristics of the proposed system are compared with the corresponding characteristics of a reference system which has been judged to be safe. Provided that the proposed system can be demonstrated to be similar to or better than the reference system in all safety-related aspects, then it may be assumed to be safe….”
Chapter 6 of ICAO Document 9689 specifically deals with the issue of comparison with a reference system. Paragraph 6.3 and 6.4 state:
“whatever reference system is chosen, it must bear a sufficiently close resemblance to the proposed system for any comparison with regard to safety to be valid. The levels of air traffic service provided in the reference and proposed airspaces, as defined by the ICAO airspace classifications, should be examined. The air traffic service in the proposed system should provide at least the same level of service as the reference system.
The minimum requirements for a reference system to be considered similar to a proposed system are:
a. Separation minima should not be less in the proposed system than in the reference system;
b. proposed means of communication and surveillance must be no worse in terms of accuracy, reliability, integrity and availability than those of the reference system;
c. frequency and duration of the application of minimum separation between aircraft must not be greater in the proposed system than in the reference system; and
d. navigation performance [typical and non-typical] of the population of aircraft in the proposed system should be no worse in its effect on collision risk, in any dimension, than that of aircraft in the reference system”.
Paragraph 6.8 then states:
“Once a reference system has been chosen, the airspace planner must perform the following steps to evaluate the relative safety of the two systems:
1. describe in detail the differences and similarities between the two systems. This must be done for all of the criteria in Chapter 3 [refer extract below];
2. For each criterion, assess how any differences between the systems would affect the risk. This can be done using mathematical techniques and/or using operational judgment. However, care must be taken to identify situations where the effect on collision risk is counter-intuitive. For example, an increase in lateral navigation accuracy, whilst decreasing collision risk in the lateral dimension, could actually increase the risk of a collision in the longitudinal or vertical dimensions. Furthermore, where risk is dominated by the occurrence of large operational errors, an increase in lateral navigation accuracy may even increase the lateral collision risk;
3. For each criterion, ensure that the proposed system is at least as safe as the reference system. Alternatively, a trade-off between factors, which are worse, and those which are better than the reference system, may be possible.
Chapter 3 of ICAO Document 9689 states, verbatim:
CHAPTER 3
DESCRIPTION OF THE CURRENT AIRSPACE AND THE CNS/ATM SYSTEMS
DETERMINING SEPARATION MINIMA
3.1 In determining appropriate separation minima, the airspace planner must have a thorough knowledge of the existing airspace, the CNS/ATM capabilities and the airspace characteristics, which may influence the safe separation minima. There are a number of factors that may influence the separation minima and these include:
3.2 Airspace structure:
a) route structure, e.g. the use of parallel or non-parallel ATS routes and whether they are bi-directional or unidirectional;
b) existing separation minima and how often values close to the separation minima are used in practice;
c) complexity of the airspace, including inter alia:
1) traffic demand pattern,
2) numbers and locations of crossing tracks,
3) amount of traffic operating on opposite direction tracks,
4) amount of traffic which is either climbing or descending,
5) nature of the aircraft population, i.e. the diversity of traffic with respect to aircraft performance and equipage (e.g. mix of various speeds, climb performance, desired optimal flight levels),
6) peak and average traffic demands versus system capacity,
7) runway capacities and the limitations of associated ground services,
8) any adjoining special-use airspace, airspace usage and types of activities including the civil/military mix, and
9) regional meteorological conditions (e.g. the prevalence of convective storms etc), and
d) designated airspace classifications.
3.3 Communication capability:
a) direct controller/pilot voice communication (VHF/HF/SATCOM);
b) indirect controller/pilot voice communication (HF);
c) controller/pilot data link communication (CPDLC);
d) controller/controller voice and automated data link communication, both inter and intra ATS unit(s);
e)data link between ground ATC automation systems and aircraft flight management computers; and
f)system availability, reliability and capacity;
3.4 Surveillance capability:
a) procedural dependent surveillance:
1)content of pilot position reports, and
2)reporting intervals;
b) automatic dependent surveillance (ADS):
1) basic update rate,
2) display accuracy,
3) ADS contract (e.g. events triggering increased reporting rate),
4) sensor accuracy,
5) system reliability, and
6) end-to-end communications time capabilities; and
c) independent surveillance (radar):
1) type of sensor (primary or secondary),
2)coverage area,
3)processing and associated delays,
4)accuracy of measured position after processing,
5)update rate,
6)display accuracy, and
7)system reliability.
3.5 Aircraft navigation performance:
a)required navigation performance (RNP);
b)typical and non-typical performance (e.g. MASPS/MOPS), (RTCA SC181 documents refer); and
c)time-keeping accuracy.
3.6 Flow management capability (ability to control traffic input to ATC):
a) strategic air traffic flow management;
b) tactical air traffic flow management;
c) ad hoc ATC “in trail” restrictions or enhancements; and
d) procedural restrictions (e.g. through local operating procedures).
3.7 Air traffic management tools to reduce controller workload or improve controller intervention capability:
a)automated controller planning tools, including conflict prediction and resolution;
b)controller displays; and
c)out-of-conformance alerts (3-D) (i.e. automatic systems which alert ATC to any deviation of an aircraft from its nominal path).
The Department of Transport and Regional Services web-site makes the following statement in relation to the design principles document:
“…The following document was finalised on 14 December 2001 and details the original NAS Australia proposal. It was part of the report prepared by the ARG for the Minister for Transport and Regional Services in March 2002, which was considered and agreed to by the Government on 13 May 2002…”
We have not seen any evidence in publicly available material that any such detailed comparative analysis had been carried out in providing advice to your airspace administrators.
If this is the case, then it is entirely possible that misleading or incorrect information may have been provided to your Minister for Transport and Regional Services, and that may have prompted incorrect decision making processes.
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Best and/or North American Practice in Airspace Management
We have seen repeated reference to airspace management based on world’s best practice, and the use of an airspace system based on practices in North America – notably the United States of America and Canada.
There are a number of technical publications which outline the principles and processes for airspace design and management used by the Federal Aviation Administration of the United States of America. These are freely available, both on the internet and direct from the address at the end of this post. We have reproduced below a [relatively] short description of the airspace management process used by the Federal Aviation Administration, as published in the Airspace Management Handbook.
THE AIRSPACE MANAGEMENT HANDBOOK
The Airspace Management Handbook has been prepared primarily for the specialists in the field who may have to initiate or participate in the process of making changes to the airspace structure. …….. Included in the guidelines are references to other, more-detailed documents that provide even more amplification on some elements of the airspace management process.
OUTLINE FOR HANDBOOK
1. CHARACTERIZE PROBLEM
Problems with airspace design or structure are often identified internally from within the Federal Aviation Administration (FAA) or by sources external to the FAA such as National Airspace System (NAS) users, airport authorities, or communities. In most cases, the FAA field facility that is affected by a problem or its solution will have primary responsibility for examining the issues. FAA Headquarters will probably be responsible for issues that involve multiple regions or national airspace. Characterization of the problem is crucial since it sets the stage for the subsequent phases of study. It is important to ensure that problem characterization does not repackage the original issue, but rather determines the true nature of the problem and extracts the root cause. The approach for characterizing a problem should be tailored to fit the situation. The approach can be very simple, relying heavily on anecdotes and judgment, or it can be a sophisticated application of tools to analyze data. In all cases, some analysis will be required along the lines of the basic principals of the scientific method. Problem characterization can be an iterative process, with the possibility that any new investigation could open additional questions about the nature and extent of the problem. Step 1 can also be interactive with Step 2, Initial Evaluation. See the Guidelines, Step 1, for a more detailed discussion of problem characterization.
2. PERFORM INITIAL EVALUATION
Not all problems or issues identified with the use of the NAS need to be resolved through a change in the airspace structure. As described in Step 1, the characterization of some perceived problems shows that they are not problems at all. Many real problems can be resolved without resorting to changes in the airspace structure. As with all problems, NAS problems should be resolved in an expeditious manner with the least amount of effort and resources expended. Only when it is clearly indicated should changes to the airspace structure be considered. Initial evaluation is performed to develop various alternatives to solve the problems and to support (justify) necessary action. The initial evaluation process usually begins at the field facility where the problem is perceived to exist, or where the proposed operational change would have the greatest impact. The initial evaluation, and possibly the resolution, can sometimes be conducted by a small group of people, based on their expert judgment and knowledge of the circumstances. See the Guidelines, Step 2, for a more detailed discussion of the initial evaluation process.
3. INITIATE AIRSPACE STUDY
If an airspace study is to be performed, then an airspace design team must be formed. The airspace design team is named by the cognizant regional airspace manager, or the lead organization for the airspace analysis. The airspace design team drafts the charter for the proposed study. Charter development assists the airspace design team in determining if additional membership is needed, including outside stakeholders. The draft charter for the airspace study will be provided to FAA Headquarters for review and coordination. The first task of the expanded airspace design team (which may now include stakeholder representatives, members from other regions, and perhaps a member from ATA-200 as well as other FAA Headquarters organizations), is to develop a comprehensive study plan. The scope of the study should generally correspond to the complexity of the proposed change, the number of facilities involved, and the potential impact of the proposed changes. See the Guidelines, Step 3, for a more detailed discussion of how to initiate an airspace study.
4. CONDUCT AIRSPACE STUDY
Every study should begin with a re-statement of the problem. This statement must be able to be clearly understood by all. The study team should be specific when documenting the issues. A specific statement of the primary issues is easier to understand, and makes it easier to plan subsequent analyses. A formal written statement of the problem is required. The most important ingredient to the successful airspace study is the appointment of a single, capable study manager to ensure all the study goals are met. If there are complicated and unique issues surrounding a study, the study team should take advantage of ATA-200 or the National Airspace Laboratory for assistance in the development of assumptions or alternatives, collection of data, or determination of metrics.
a. revalidate problem statement
b. select and define metrics
c. identify alternatives
d. determine type of analysis
e. select tool(s)
f. obtain input data
g. define baseline and alternative scenarios
h. adapt, calibrate, and validate model
i. make production runs
j. analyze model output
k. perform sensitivity analysis
l. conduct human-in-the-loop testing and evaluation
5. SUMMARIZE AND PRESENT RESULTS
The analyses performed, and the conclusions and recommendations derived from those analyses, should be documented in a formal study report. The formal study report should specify recommended airspace actions, sector realignments, route adjustments, and procedural changes necessary to implement the recommendations. An example outline for the study report is included in the guidelines. A formal study report is important because it conveys the key findings of the study to decision makers and stakeholders. A study report also documents the analysis and recommendations for historical reference. See the Guidelines, Step 5, for a more detailed discussion of preparing the final study report.
6. PLAN IMPLEMENTATION AT FIELD FACILITY
Careful consideration of actions necessary to implement recommended airspace changes should be a part of the overall planning process. Although implementation issues ought to be considered throughout the study process, detailed implementation planning should begin immediately after approval for the airspace change. Careful implementation planning is necessary for airspace changes to avoid any interruption of air traffic services, to minimize any disruption of air traffic, and to communicate what airspace changes are to occur. Facilities implementing an airspace change should develop an Implementation Plan and a Transition Plan, which should together lay out an achievable schedule and describe the steps required to successfully coordinate and enact the change. Involvement of the users is imperative in developing the Implementation and Transition Plans, and in actually implementing the airspace changes. See the Guidelines, Step 6, for a more detailed discussion of planning the implementation of airspace changes at the field facility.
7. EVALUATE IMPLEMENTATION
Airspace changes should be evaluated after implementation to measure their success. Once in place, changes to the National Airspace System should be assessed to verify that the objectives specified in the Implementation Plan are achieved, to provide lessons learned concerning the process, and to ensure improved service to users of the National Airspace System. See the Guidelines, Step 7, for a more detailed discussion of post-implementation evaluation of the impact of changes.
Further information can be obtained from:
FEDERAL AVIATION ADMINISTRATION
OFFICE OF AIR TRAFFIC AIRSPACE MANAGEMENT
PLANNING AND ANALYSIS DIVISION (ATA-200)
800 INDEPENDENCE AVENUE, SW
WASHINGTON, DC 20591
There are a number of technical publications which outline the principles and processes for airspace design and management used by the Federal Aviation Administration of the United States of America. These are freely available, both on the internet and direct from the address at the end of this post. We have reproduced below a [relatively] short description of the airspace management process used by the Federal Aviation Administration, as published in the Airspace Management Handbook.
THE AIRSPACE MANAGEMENT HANDBOOK
The Airspace Management Handbook has been prepared primarily for the specialists in the field who may have to initiate or participate in the process of making changes to the airspace structure. …….. Included in the guidelines are references to other, more-detailed documents that provide even more amplification on some elements of the airspace management process.
OUTLINE FOR HANDBOOK
1. CHARACTERIZE PROBLEM
Problems with airspace design or structure are often identified internally from within the Federal Aviation Administration (FAA) or by sources external to the FAA such as National Airspace System (NAS) users, airport authorities, or communities. In most cases, the FAA field facility that is affected by a problem or its solution will have primary responsibility for examining the issues. FAA Headquarters will probably be responsible for issues that involve multiple regions or national airspace. Characterization of the problem is crucial since it sets the stage for the subsequent phases of study. It is important to ensure that problem characterization does not repackage the original issue, but rather determines the true nature of the problem and extracts the root cause. The approach for characterizing a problem should be tailored to fit the situation. The approach can be very simple, relying heavily on anecdotes and judgment, or it can be a sophisticated application of tools to analyze data. In all cases, some analysis will be required along the lines of the basic principals of the scientific method. Problem characterization can be an iterative process, with the possibility that any new investigation could open additional questions about the nature and extent of the problem. Step 1 can also be interactive with Step 2, Initial Evaluation. See the Guidelines, Step 1, for a more detailed discussion of problem characterization.
2. PERFORM INITIAL EVALUATION
Not all problems or issues identified with the use of the NAS need to be resolved through a change in the airspace structure. As described in Step 1, the characterization of some perceived problems shows that they are not problems at all. Many real problems can be resolved without resorting to changes in the airspace structure. As with all problems, NAS problems should be resolved in an expeditious manner with the least amount of effort and resources expended. Only when it is clearly indicated should changes to the airspace structure be considered. Initial evaluation is performed to develop various alternatives to solve the problems and to support (justify) necessary action. The initial evaluation process usually begins at the field facility where the problem is perceived to exist, or where the proposed operational change would have the greatest impact. The initial evaluation, and possibly the resolution, can sometimes be conducted by a small group of people, based on their expert judgment and knowledge of the circumstances. See the Guidelines, Step 2, for a more detailed discussion of the initial evaluation process.
3. INITIATE AIRSPACE STUDY
If an airspace study is to be performed, then an airspace design team must be formed. The airspace design team is named by the cognizant regional airspace manager, or the lead organization for the airspace analysis. The airspace design team drafts the charter for the proposed study. Charter development assists the airspace design team in determining if additional membership is needed, including outside stakeholders. The draft charter for the airspace study will be provided to FAA Headquarters for review and coordination. The first task of the expanded airspace design team (which may now include stakeholder representatives, members from other regions, and perhaps a member from ATA-200 as well as other FAA Headquarters organizations), is to develop a comprehensive study plan. The scope of the study should generally correspond to the complexity of the proposed change, the number of facilities involved, and the potential impact of the proposed changes. See the Guidelines, Step 3, for a more detailed discussion of how to initiate an airspace study.
4. CONDUCT AIRSPACE STUDY
Every study should begin with a re-statement of the problem. This statement must be able to be clearly understood by all. The study team should be specific when documenting the issues. A specific statement of the primary issues is easier to understand, and makes it easier to plan subsequent analyses. A formal written statement of the problem is required. The most important ingredient to the successful airspace study is the appointment of a single, capable study manager to ensure all the study goals are met. If there are complicated and unique issues surrounding a study, the study team should take advantage of ATA-200 or the National Airspace Laboratory for assistance in the development of assumptions or alternatives, collection of data, or determination of metrics.
a. revalidate problem statement
b. select and define metrics
c. identify alternatives
d. determine type of analysis
e. select tool(s)
f. obtain input data
g. define baseline and alternative scenarios
h. adapt, calibrate, and validate model
i. make production runs
j. analyze model output
k. perform sensitivity analysis
l. conduct human-in-the-loop testing and evaluation
5. SUMMARIZE AND PRESENT RESULTS
The analyses performed, and the conclusions and recommendations derived from those analyses, should be documented in a formal study report. The formal study report should specify recommended airspace actions, sector realignments, route adjustments, and procedural changes necessary to implement the recommendations. An example outline for the study report is included in the guidelines. A formal study report is important because it conveys the key findings of the study to decision makers and stakeholders. A study report also documents the analysis and recommendations for historical reference. See the Guidelines, Step 5, for a more detailed discussion of preparing the final study report.
6. PLAN IMPLEMENTATION AT FIELD FACILITY
Careful consideration of actions necessary to implement recommended airspace changes should be a part of the overall planning process. Although implementation issues ought to be considered throughout the study process, detailed implementation planning should begin immediately after approval for the airspace change. Careful implementation planning is necessary for airspace changes to avoid any interruption of air traffic services, to minimize any disruption of air traffic, and to communicate what airspace changes are to occur. Facilities implementing an airspace change should develop an Implementation Plan and a Transition Plan, which should together lay out an achievable schedule and describe the steps required to successfully coordinate and enact the change. Involvement of the users is imperative in developing the Implementation and Transition Plans, and in actually implementing the airspace changes. See the Guidelines, Step 6, for a more detailed discussion of planning the implementation of airspace changes at the field facility.
7. EVALUATE IMPLEMENTATION
Airspace changes should be evaluated after implementation to measure their success. Once in place, changes to the National Airspace System should be assessed to verify that the objectives specified in the Implementation Plan are achieved, to provide lessons learned concerning the process, and to ensure improved service to users of the National Airspace System. See the Guidelines, Step 7, for a more detailed discussion of post-implementation evaluation of the impact of changes.
Further information can be obtained from:
FEDERAL AVIATION ADMINISTRATION
OFFICE OF AIR TRAFFIC AIRSPACE MANAGEMENT
PLANNING AND ANALYSIS DIVISION (ATA-200)
800 INDEPENDENCE AVENUE, SW
WASHINGTON, DC 20591