Airspace Design - Some Background
Could we please get the JFK question sorted, once and for all?
A very, very simple question, on a very specific matter of fact: Do Jumbo jets arriving or departing JFK get routed through or otherwise transit class E airspace as a matter of procedure or practice?
Chris Higgins – is Dick right or wrong when he implies that they do? If he’s right, please acknowledge that he is. If he’s wrong, please explain why.
If we can’t work out what classes of airspace are around JFK as a matter of simple fact, and work out what aircraft fly through it as a matter of simple fact, then it’s no wonder these discussions go in circles.
Chris Higgins – is Dick right or wrong when he implies that they do? If he’s right, please acknowledge that he is. If he’s wrong, please explain why.
If we can’t work out what classes of airspace are around JFK as a matter of simple fact, and work out what aircraft fly through it as a matter of simple fact, then it’s no wonder these discussions go in circles.
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Creampuff
With all due respects Who gives a flying f*&#k how Jumbos get into JFK, the question still is is it safer than what we had before? The answer is still obvious from the statistics and that is a resouding "no". I asked earlier and probably in another thread "who decides just what constitutes worlds best practice? but have yet to see any reply. America has had MACs involving RPT aircraft whereas OZ has not. The question is which is worlds best practice? It all comes down to point of view, doesn't it.
I think I would prefer worlds best safety practice, wouldn't you?
Dick
I'm glad I didn't hold my breath waiting for your reply!
I am glad i am not one of the Ozzie companies who have gambled their future on your support, as with your continued reluctance to accept the error of this debacle you do damage to those you claim to support. Please do not claim that as people turn on your image it only damages innocent ozzie producers as it comes down to the fact that it only damages them if they continue to remain associated with your public image.
With due respect your image is becoming tarnished (in my humble opinion) and it is time to accept that you were wrong. I don't care how you eat humble pie, but it is a meal long overdue, Please don't hold onto your beliefs to the expense of Australian Aviation.
Enough is enough call a halt now! Whilst you can still hold some credibility.
With all due respects Who gives a flying f*&#k how Jumbos get into JFK, the question still is is it safer than what we had before? The answer is still obvious from the statistics and that is a resouding "no". I asked earlier and probably in another thread "who decides just what constitutes worlds best practice? but have yet to see any reply. America has had MACs involving RPT aircraft whereas OZ has not. The question is which is worlds best practice? It all comes down to point of view, doesn't it.
I think I would prefer worlds best safety practice, wouldn't you?
Dick
I'm glad I didn't hold my breath waiting for your reply!
I am glad i am not one of the Ozzie companies who have gambled their future on your support, as with your continued reluctance to accept the error of this debacle you do damage to those you claim to support. Please do not claim that as people turn on your image it only damages innocent ozzie producers as it comes down to the fact that it only damages them if they continue to remain associated with your public image.
With due respect your image is becoming tarnished (in my humble opinion) and it is time to accept that you were wrong. I don't care how you eat humble pie, but it is a meal long overdue, Please don't hold onto your beliefs to the expense of Australian Aviation.
Enough is enough call a halt now! Whilst you can still hold some credibility.
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CA/GRS and CA/GRO
I was very disturbed when I read what Walley2 said above
I surely can't believe this. CA/GRS?
Does this mean that NASIG are arbitrarily taking away the certified air ground radio operator service at Broome and Ayres Rock?
Is this the final step on the path from good intentions, through blindly charging ahead, through ineptness, and now finally down to derangement?
Or is derangement the fact that NASIG are now pressing ahead with implementation of NAS 2c
http://www.pprune.org/forums/showthr...hreadid=120419
Why then am I informed, after my enquiry, by NASIG that they have asked CASA to delete the regs on CAGRS as they are "non compliant to NAS."
Does this mean that NASIG are arbitrarily taking away the certified air ground radio operator service at Broome and Ayres Rock?
Is this the final step on the path from good intentions, through blindly charging ahead, through ineptness, and now finally down to derangement?
Or is derangement the fact that NASIG are now pressing ahead with implementation of NAS 2c
we intend to conduct safety workshops in the near future to cover the changes that are planned for implementation in November 2004 as Stage 2c of the NAS
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CLASS D AIRSPACE CHANGES IN NAS 2C
We note in the last posting reference to NAS 2C, that one of the proposed changes in the next airspace change tranche is to amend Class D procedures. Our understanding from examining the NAS documentation is that this will involve a change in VFR entry procedures, so that simple acknowledgement of a call by VFR aircraft at the boundary may be taken as a clearance (implicit rather than explicit) to enter Class D airspace (on-line at the NAS website via Airservices Australia’s web-site) .
We have reviewed your AIP (on-line at Airservices Australia) and note that the current procedures require VFR flights to obtain a positive clearance to enter Class D airspace.
We note that the NAS 2C changes will not amend airspace boundaries for Class D – i.e., VFR flights may enter Class D airspace at a boundary distance of more than 20 nautical miles. At that distance it would be impossible for air traffic control to positively sight and identify the aircraft concerned, and provide a meaningful service between IFR and VFR flights.
We have examined the United States procedures (AIM and ATC Documents (7110.65)) and note that Class D airspace in the United Stated most often extends to a maximum of 7 miles (typically 5 miles) and upper limits in the range of 2000 feet at each of the several hundred Class D towers (refer also FAA web-site at www.faa.gov). As is the case with aircraft entering your GAAP airspace (ref Australian AIP) it would definitely be possible for a controller to sight, identify, and provide services in respect of that aircraft, even with an implicit clearance.
This begs the question of the potential changes in risk that would be associated not only with the implementation (as has been claimed in respect of other changes) but also with the actual design itself.
We referred again to ICAO DOCUMENT 9689 - MANUAL ON AIRSPACE PLANNING METHODOLOGY FOR THE DETERMINATION OF SEPARATION MINIMA. That document contains an appendix submitted by Australia which outlines an airspace risk model for small terminal areas – CTAF and MBZ.
We understand that in 1996, attempts were made to change the Class C airspace associated with 12 regional non-radar towers to Class D airspace. We have been provided information that indicates that there e was significant community opposition, and significant debate, which forced a review of that decision. A particularly detailed risk study was conducted, a 1997 copy of which was provided to one of our members.
The report of that study indicated that the change from Class C to Class D would increase risk in the order of ten-fold. In some cases, this brought the risk close to (but not above) the limits of tolerability – however Airservices Australia was able to implement the change to Class D in 1997.
The study built on the airspace risk model that had been presented to, and accepted by, ICAO. It is therefore reasonable to say that the modeling carried out on Class C and Class D airspace would fall within a statement that “it was based on ICAO guidance material”.
We have examined the model and find that it contains a number of fault tree decision points, the likelihoods of which were determined from industry panel inputs.
It would therefore be relatively easy to re-assess the likelihood of certain events occurring if VFR aircraft were NOT subject to positive clearance – i.e., were potentially likely to enter controlled airspace by accident. A change in likelihood in just a few decision points can have dramatic effect on risk – to the point where the risk at a small number of the Class D towers would EXCEED the tolerable risk limits.
It should not require a great deal of effort on the part of Airservices Australia to re-model the proposed changes and provide a public risk statement.
We are not in a position to directly intervene here, but we believe that you should challenge your service provider both to re-release the risk analysis already done on Class D airspace – AND to carry out the re-analysis based on the changed procedure.
Summarizing, it is our considered judgment that without a commensurate change in the size of the Class D airspace to replicate the United States situation, the levels of risk to both IFR and VFR flights in Class D airspace would elevate significantly and may exceed already established risk tolerability limits.
Our apologies.
We omitted to add in our previous post that should the Class D airspace limits be amended to those applicable in the United States, a commensurate increase or lowering of Class E airspace would be required (as applies in the United States). This would result in the potential for unannounced VFR flights to transit above Class D towers at 2500 feet.
In short, not only will the risk in residual Class D be raised, but the risk in the volume previously categorised as Class D - i.e,. that airspace that becomes Class E - would increase even further than had it remained Class D with new procedures. The risk in Class E airspace between 2500 feet and 4500 feet can easily and validly be modelled within the model agreed by ICAO and referred to in the previous post (the Class D risk analysis conducted by Airservices Australia).
We re-iterate that it is our considered judgment that the levels of risk at certain Class D locations may rise above previously agreed risk thresholds, and in the risk workshops being conducted by your NAS teams, you must challenge them both to release that study, and commit to a re-calculation of design (and not implementation) risk.
We have reviewed your AIP (on-line at Airservices Australia) and note that the current procedures require VFR flights to obtain a positive clearance to enter Class D airspace.
We note that the NAS 2C changes will not amend airspace boundaries for Class D – i.e., VFR flights may enter Class D airspace at a boundary distance of more than 20 nautical miles. At that distance it would be impossible for air traffic control to positively sight and identify the aircraft concerned, and provide a meaningful service between IFR and VFR flights.
We have examined the United States procedures (AIM and ATC Documents (7110.65)) and note that Class D airspace in the United Stated most often extends to a maximum of 7 miles (typically 5 miles) and upper limits in the range of 2000 feet at each of the several hundred Class D towers (refer also FAA web-site at www.faa.gov). As is the case with aircraft entering your GAAP airspace (ref Australian AIP) it would definitely be possible for a controller to sight, identify, and provide services in respect of that aircraft, even with an implicit clearance.
This begs the question of the potential changes in risk that would be associated not only with the implementation (as has been claimed in respect of other changes) but also with the actual design itself.
We referred again to ICAO DOCUMENT 9689 - MANUAL ON AIRSPACE PLANNING METHODOLOGY FOR THE DETERMINATION OF SEPARATION MINIMA. That document contains an appendix submitted by Australia which outlines an airspace risk model for small terminal areas – CTAF and MBZ.
We understand that in 1996, attempts were made to change the Class C airspace associated with 12 regional non-radar towers to Class D airspace. We have been provided information that indicates that there e was significant community opposition, and significant debate, which forced a review of that decision. A particularly detailed risk study was conducted, a 1997 copy of which was provided to one of our members.
The report of that study indicated that the change from Class C to Class D would increase risk in the order of ten-fold. In some cases, this brought the risk close to (but not above) the limits of tolerability – however Airservices Australia was able to implement the change to Class D in 1997.
The study built on the airspace risk model that had been presented to, and accepted by, ICAO. It is therefore reasonable to say that the modeling carried out on Class C and Class D airspace would fall within a statement that “it was based on ICAO guidance material”.
We have examined the model and find that it contains a number of fault tree decision points, the likelihoods of which were determined from industry panel inputs.
It would therefore be relatively easy to re-assess the likelihood of certain events occurring if VFR aircraft were NOT subject to positive clearance – i.e., were potentially likely to enter controlled airspace by accident. A change in likelihood in just a few decision points can have dramatic effect on risk – to the point where the risk at a small number of the Class D towers would EXCEED the tolerable risk limits.
It should not require a great deal of effort on the part of Airservices Australia to re-model the proposed changes and provide a public risk statement.
We are not in a position to directly intervene here, but we believe that you should challenge your service provider both to re-release the risk analysis already done on Class D airspace – AND to carry out the re-analysis based on the changed procedure.
Summarizing, it is our considered judgment that without a commensurate change in the size of the Class D airspace to replicate the United States situation, the levels of risk to both IFR and VFR flights in Class D airspace would elevate significantly and may exceed already established risk tolerability limits.
Our apologies.
We omitted to add in our previous post that should the Class D airspace limits be amended to those applicable in the United States, a commensurate increase or lowering of Class E airspace would be required (as applies in the United States). This would result in the potential for unannounced VFR flights to transit above Class D towers at 2500 feet.
In short, not only will the risk in residual Class D be raised, but the risk in the volume previously categorised as Class D - i.e,. that airspace that becomes Class E - would increase even further than had it remained Class D with new procedures. The risk in Class E airspace between 2500 feet and 4500 feet can easily and validly be modelled within the model agreed by ICAO and referred to in the previous post (the Class D risk analysis conducted by Airservices Australia).
We re-iterate that it is our considered judgment that the levels of risk at certain Class D locations may rise above previously agreed risk thresholds, and in the risk workshops being conducted by your NAS teams, you must challenge them both to release that study, and commit to a re-calculation of design (and not implementation) risk.
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We may be in a position to provide more explicit information via direct contact, or to validate information we have received from other sources and post that information for general viewing.
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Thank you Mr Smith..
In the fourteen years since I have left Australia, I never thought I would read a post where Dick Smith said he has "worried" about me. Don't worry Mr Smith, I have not endangered anybody with my ignorance.
Yes, technically you're correct. From the base of the Positive Control Area (Class A) to the top of Class B ( the old terminal area), there is in fact a vertical transition through Class E. But the arrival overlays from Class A to Class B, there is no, "no man's land" in between. This observation is not based upon ignorance.
Yes, you're correct about my flying in Class E airspace, in fact I did it today enroute from Los Angeles, and let's talk about that too.
The departure today was one of many variations of "The Loop" which callled on this occasion for a transition over Thermal, near Palm Springs. The SID allows you to climb in Class B over the initial departure with a turn out over the ocean before returning over the Los Angeles Airport and transitioning via an unrestricted climb into the Positive Control Area.
Why? Partly so we don't run into the Sierra Nevadas, also to allow airspace for descending arrivals from the East and also to allow us to make a transition through E airspace from underlying Class B to minimize risk and facilitate a rapid transition to Class A.
The differences Mr Smith are that you are proposing what was once called cynically, "NO SAR/ No brains" as the normal part of a vast majority of your Australian airspace and expecting thousands of passengers hurtling through the sky at well over 250 knots above 10,000 feet to be protected by little more than the Mark I eyeball.
Are you expecting us to believe that people in their gliders and Cessnas are flying over LAX, JFK and San Francisco, without talking to anybody before they get there, because they remain solely in Class E? And are you suggesting that they do it without transponder?
Well to answer my own...
First of all. You can't operate anywhere within 30 miles of Class B in the United States without an operable Mode C. Yes Dick, I know it's possible on occasion to get a waiver, but they're rare now.
Denying us the obvious implications of September 11, 2001, (where anyone showing up over downtown Manhattan without contact would be escorted by fighters), it would be extremely unusual for a pilot who pays taxes to fly an aeroplane, to take off from a towered airport, get a transition through Class C airspace then continue to climb into Class E airspace without a discreet code and a courtesy hand-off for further flight following.
YOU might do it Dick, but none of us would!
No I won't correct my post. I'm too busy, I've got to get back to the West Coast to the Academy Awards.
Yes, technically you're correct. From the base of the Positive Control Area (Class A) to the top of Class B ( the old terminal area), there is in fact a vertical transition through Class E. But the arrival overlays from Class A to Class B, there is no, "no man's land" in between. This observation is not based upon ignorance.
Yes, you're correct about my flying in Class E airspace, in fact I did it today enroute from Los Angeles, and let's talk about that too.
The departure today was one of many variations of "The Loop" which callled on this occasion for a transition over Thermal, near Palm Springs. The SID allows you to climb in Class B over the initial departure with a turn out over the ocean before returning over the Los Angeles Airport and transitioning via an unrestricted climb into the Positive Control Area.
Why? Partly so we don't run into the Sierra Nevadas, also to allow airspace for descending arrivals from the East and also to allow us to make a transition through E airspace from underlying Class B to minimize risk and facilitate a rapid transition to Class A.
The differences Mr Smith are that you are proposing what was once called cynically, "NO SAR/ No brains" as the normal part of a vast majority of your Australian airspace and expecting thousands of passengers hurtling through the sky at well over 250 knots above 10,000 feet to be protected by little more than the Mark I eyeball.
Are you expecting us to believe that people in their gliders and Cessnas are flying over LAX, JFK and San Francisco, without talking to anybody before they get there, because they remain solely in Class E? And are you suggesting that they do it without transponder?
Well to answer my own...
First of all. You can't operate anywhere within 30 miles of Class B in the United States without an operable Mode C. Yes Dick, I know it's possible on occasion to get a waiver, but they're rare now.
Denying us the obvious implications of September 11, 2001, (where anyone showing up over downtown Manhattan without contact would be escorted by fighters), it would be extremely unusual for a pilot who pays taxes to fly an aeroplane, to take off from a towered airport, get a transition through Class C airspace then continue to climb into Class E airspace without a discreet code and a courtesy hand-off for further flight following.
YOU might do it Dick, but none of us would!
No I won't correct my post. I'm too busy, I've got to get back to the West Coast to the Academy Awards.
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Before I go.....
We are going to be out of duty time...so I'm here for the night.
I just got a call in to Australia. It seems to me that it's a lot worse over there than I feared.
Just to reiterate:
Boston, Chicago, JFK, La Guardia, Pittsburgh, Philadelphia and Washington, Baltimore, Cleveland, Denver, Dallas, Memphis etc...etc are all Class B airspace which now I understand Australia hasn't even graduated to yet!!
The deal here is that NO aircraft can be admitted without a clearance and ALL movements are controlled at ALL times.
NO aircraft in America is permitted above 10,000 feet MSL without an altitude reporting transponder. In addition NO aircraft is allowed to operate at ANY airport within 30 nautical miles of a Class B airport at ANY ALTITUDE unless they they have a Mode C transponder.
The very thought of descending through Class E airspace with the knowledge that a high proportion are not communicating and might not have confirmed with center/approach of the servicability of their transponders is simply not acceptable.
As a Certified Flight (Flying) Instructor, I always taught students to establish contact with Center as soon as possible after departure from my non-controlled airport and achieve flight following with a discreet code and continuous communication. We never had any problems.
Dick, this is nothing like you have in Australia. From my conversations tonight, it sounds like you are discouraging VFR traffic from talking to already concerned and overworked controllers, and hoping for the best.
Your Class E analogies, using American examples, have absolutely no relationship to your arguments!
I just got a call in to Australia. It seems to me that it's a lot worse over there than I feared.
Just to reiterate:
Boston, Chicago, JFK, La Guardia, Pittsburgh, Philadelphia and Washington, Baltimore, Cleveland, Denver, Dallas, Memphis etc...etc are all Class B airspace which now I understand Australia hasn't even graduated to yet!!
The deal here is that NO aircraft can be admitted without a clearance and ALL movements are controlled at ALL times.
NO aircraft in America is permitted above 10,000 feet MSL without an altitude reporting transponder. In addition NO aircraft is allowed to operate at ANY airport within 30 nautical miles of a Class B airport at ANY ALTITUDE unless they they have a Mode C transponder.
The very thought of descending through Class E airspace with the knowledge that a high proportion are not communicating and might not have confirmed with center/approach of the servicability of their transponders is simply not acceptable.
As a Certified Flight (Flying) Instructor, I always taught students to establish contact with Center as soon as possible after departure from my non-controlled airport and achieve flight following with a discreet code and continuous communication. We never had any problems.
Dick, this is nothing like you have in Australia. From my conversations tonight, it sounds like you are discouraging VFR traffic from talking to already concerned and overworked controllers, and hoping for the best.
Your Class E analogies, using American examples, have absolutely no relationship to your arguments!
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As a Certified Flight (Flying) Instructor, I always taught students to establish contact with Center as soon as possible after departure from my non-controlled airport and achieve flight following with a discreet code and continuous communication. We never had any problems.
I seem to recall the last Flight Service unit in Australia was 'decommissioned' about 10 years ago.
Chris Higgins –your short point appears to be that although heavy metal transits class E, VFR aircraft are never there unannounced or unverified.
A supplementary question if I may: is the process through which the VFRs make themselves known and get their transponders verified, a legal requirement or just a matter of general practice?
justapplhere –your short point is, as usual, pointless. But please post whatever makes the voices in your head happy.
A supplementary question if I may: is the process through which the VFRs make themselves known and get their transponders verified, a legal requirement or just a matter of general practice?
justapplhere –your short point is, as usual, pointless. But please post whatever makes the voices in your head happy.
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Cream Puff...and all.
I was there just the other night in Salt Lake City at Millionaire. A really nice spot. Perhaps on my next overnight we should talk about this some more.
With respect to the arrivals into any major US airport, they really share one thing in common that really alarms me about the NAS in Australia. We make these arrivals Stateside into Class B airspace. The ramifications of this are very real. Real control of real, and not assumed traffic, operating on identifiable transponder codes and in continuous two-way communication with a controlling authority.
Class C airspace dictates the need for communication and transponder usage, but no real control over VFR behaviours (behaviors).
Transiting the Australian interpretation of Class E airspace requires no transponder and no communication with a traffic advisory service. Dick Smith will point out to me that in the Midwest of the USA, this is not unusual...but he's wrong.
Nobody that spends a minimum of $180,000 on a Cessna 172 is only going to want to fly it 60 days a year. In addition, that same person pays a lot in taxes and will make full use of an instrument rating and the free services of radar following.
In 1998, a Mesa Airlines crew, was charged with "reckless endagerement" by the FAA, for flying VFR in the Northeast corridor. This was in a Beech 1900 that only carries 19 people and doesn't indicate over 250 knots in airspeed.
What Dick Smith is saying is that it's alright for a Virgin Blue crew to mix it up with non-reporting VFR Cessnas and do this with over 140 people on board and indicating over 310 knots in airspeed. My response, "Like Hell"!
To give Mr. Smith some credit, he was correct in asserting that the arrivals in New York do, in fact, transit Class E airspace. He is also correct in saying that for my three and a half years flying the turbo-props (Jetstream 41, ATR 42/72), I flew through E airspace everyday. He is completely missing the point about one thing though. Australians and Americans may both call it Class E, but, the similarity ends there!
To Ftrplt:
Class E inhabitants do in fact fly very happily in Class E and even Class B airspace. They tend to tell people where they're going though, it's the way they have developed the system here.
With respect to the arrivals into any major US airport, they really share one thing in common that really alarms me about the NAS in Australia. We make these arrivals Stateside into Class B airspace. The ramifications of this are very real. Real control of real, and not assumed traffic, operating on identifiable transponder codes and in continuous two-way communication with a controlling authority.
Class C airspace dictates the need for communication and transponder usage, but no real control over VFR behaviours (behaviors).
Transiting the Australian interpretation of Class E airspace requires no transponder and no communication with a traffic advisory service. Dick Smith will point out to me that in the Midwest of the USA, this is not unusual...but he's wrong.
Nobody that spends a minimum of $180,000 on a Cessna 172 is only going to want to fly it 60 days a year. In addition, that same person pays a lot in taxes and will make full use of an instrument rating and the free services of radar following.
In 1998, a Mesa Airlines crew, was charged with "reckless endagerement" by the FAA, for flying VFR in the Northeast corridor. This was in a Beech 1900 that only carries 19 people and doesn't indicate over 250 knots in airspeed.
What Dick Smith is saying is that it's alright for a Virgin Blue crew to mix it up with non-reporting VFR Cessnas and do this with over 140 people on board and indicating over 310 knots in airspeed. My response, "Like Hell"!
To give Mr. Smith some credit, he was correct in asserting that the arrivals in New York do, in fact, transit Class E airspace. He is also correct in saying that for my three and a half years flying the turbo-props (Jetstream 41, ATR 42/72), I flew through E airspace everyday. He is completely missing the point about one thing though. Australians and Americans may both call it Class E, but, the similarity ends there!
To Ftrplt:
Class E inhabitants do in fact fly very happily in Class E and even Class B airspace. They tend to tell people where they're going though, it's the way they have developed the system here.
Last edited by Chris Higgins; 3rd Mar 2004 at 07:53.
Chris Higgins posts seem to be lucid. I am following them with great interest as I'm moving to Phoenix in July I'll be hoping that my training in Australia doesn't confuse the heck out of me when I finalise it in the USA - I'll probably end up running that 172 into that rouge Mesa Air flight above Chandler, if I take class E from here to mean the same thing there. This is scary! May require a brain reset.
Last edited by Woomera; 4th Mar 2004 at 15:00.
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It appears the ARG is now impotent and marginalised. NASIG are seen as an incompetent creature and the instigators have been defrocked for their amateur dabbling.
It is now understood at all levels, including the Minister’s office, that they were sold a pup. Airservices are going their own way as the professional Service Provider.
Only a handful of people in Australia ever believe NAS as proposed was a "good thing". Those who dabbled have had their day. Everyone is tired of amateur enthusiasts running the Australian aviation industry.
From another post: "My source says it is an injunction to prevent the distribution of documents (charts) with frequency and boundary info thereon." That legal action will be the death throes of both.
It is now understood at all levels, including the Minister’s office, that they were sold a pup. Airservices are going their own way as the professional Service Provider.
Only a handful of people in Australia ever believe NAS as proposed was a "good thing". Those who dabbled have had their day. Everyone is tired of amateur enthusiasts running the Australian aviation industry.
From another post: "My source says it is an injunction to prevent the distribution of documents (charts) with frequency and boundary info thereon." That legal action will be the death throes of both.
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"My source says it is an injunction to prevent the distribution of documents (charts) with frequency and boundary info thereon."
I would be interested to know what legal principles are involved here. Sounds like some wishful thinking...
I would be interested to know what legal principles are involved here. Sounds like some wishful thinking...
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Extract from reports on the website of the Australian Transportation Safety Board:
……. to the outstanding recommendations contained in the 1991 BASI research report on the limitations of see and avoid. As you would be aware, most of the recommendations - including those concerning TCAS and the education initiatives - have been implemented and continue to provide positive safety outcomes for Australian aviation.
In respect of the remaining recommendations, CASA provides the following response.
"The CAA should take into account the limitations of see-and avoid when planning and managing airspace...."
CASA agrees that the limitations of see-and-avoid should be taken into account when planning and managing airspace. Where traffic densities are such that see-and-avoid does not provide the required level of safety, CASA will require Class D or a higher level of airspace.
....and should ensure that unalerted see-an-avoid is never the sole means of separation for aircraft providing scheduled services."
CASA understands the intent of this recommendation but does not agree with its absolute form. The wording of the recommendation reflected its time and was prior to the 1995 Standards Australia AS/NZS4360 Risk Management Standard. CASA also understands that the use of the absolute "never" is not consistent with current ATSB practice.
To accept the absolute form of the recommendation would require the allocation of Class D or higher airspace wherever scheduled services operate. This would result in an allocation of resources that is not commensurate with risk.
ICAO Class E and G airspace specifically has no radio requirement for VFR aircraft. ICAO has introduced both of these classifications with the full knowledge of the limitations of see-and-avoid. ICAO makes no recommendation in relation to scheduled services not operating in these airspace classifications.
Overly discounting the effectiveness of see-and-avoid and devising unique procedures has itself led to unintended consequences that are unresolved. Pilots may scan significantly less and become over reliant on radio alerting through a concept known as diffusion of responsibility. The BASI report RP/93/01 (December 1993) and the continuing incident reports that are being filed listing near misses in mandatory radio Class E and G airspace may support this concern. CASA believes that radio alerting is only effective when the alerting area is small with readily identifiable reporting points so that the alert is specific.
Extracts from United States Research:
(http://www.aviation.uiuc.edu/UnitsHF...n03/talwic.pdf)
With regard to the major issue addressed in this study, scanning strategies, the current data appears to be the first to document the effectiveness of certain scanning strategies, as measured through eye-movements, and their effectiveness measured through traffic detection performance. In this regard, it is important to note that the FAA-recommended sector scan comes up as a clear winner over all others, including slightly better performance than the recommended sweep strategy, availing increased Outside World (OW) scanning, and less disruption with flight control. The sector scan also appeared to be encouraged by the auditory condition and this auditory condition was itself associated with somewhat better traffic detection. Furthermore, this strategy is coupled with more total OW scan time (although this proportion still did not approach the FAA recommended values).
It appears that whatever strategy is generally adopted, the appearance of a cue, whether visual (CDTI) or auditory, often served to preempt that strategy, to bring scanning into the region where the traffic is expected to be seen. This qualitatively different .find cued traffic. scan pattern seems to be fairly uniform across all pilots, but may leave them vulnerable for detecting a second, unexpected traffic aircraft that might appear after the cue is presented, an observation described by Harris (1979) in traffic detection, and observed as a statistically robust consequence of cueing in both freeflight scanning (Wickens, Helleberg, & Xu, 2002), and in other target detection domains (Yeh, Wickens, & Seagull, 1999; Yeh & Wickens, 2001).
THE RESULTS HAVE ALSO SHOWN THAT CUEING OR ATTENTION GUIDANCE, PROVIDED IN EITHER MODALITY, APPEARS TO MAINTAIN DETECTION PERFORMANCE AT A LEVEL OF AROUND 90%, CLEARLY BETTER THAN THE UN-CUED RATE OF AROUND 60% REVEALED IN OTHER STUDIES, AS PREVIOUSLY MENTIONED, IN BOTH SIMULATED (WICKENS, HELLEBERG, & XU, 2002) AND REAL FLIGHT (MARSHALL & FISHER, 1959) ENVIRONMENTS. NEVERTHELESS, IT IS IMPORTANT TO NOTE THAT THIS DETECTION LEVEL STILL REMAINS FAR FROM PERFECT, AND APPEARS TO BRING WITH IT A COST OF SOME ATTENTIONAL TUNNELING.
Finally, we note that the overall ratio of OW to inside scanning (slightly less than 1:2), as observed in prior research (Harris, 1979; Wickens et al., 2002), is one that departs from FAA guidelines to favor the OW. Even though all three modality conditions in this study had other sources of traffic cueing information (ATC, CDTI, or both), parallel studies where these resources were not available (Wickens, Helleberg & Xu, 2002), have shown that the optimal ratio was still not found.
The second last paragraph indicates that unalerted see and avoid may be as much as 50% less effective than alerted see and avoid.
……. to the outstanding recommendations contained in the 1991 BASI research report on the limitations of see and avoid. As you would be aware, most of the recommendations - including those concerning TCAS and the education initiatives - have been implemented and continue to provide positive safety outcomes for Australian aviation.
In respect of the remaining recommendations, CASA provides the following response.
"The CAA should take into account the limitations of see-and avoid when planning and managing airspace...."
CASA agrees that the limitations of see-and-avoid should be taken into account when planning and managing airspace. Where traffic densities are such that see-and-avoid does not provide the required level of safety, CASA will require Class D or a higher level of airspace.
....and should ensure that unalerted see-an-avoid is never the sole means of separation for aircraft providing scheduled services."
CASA understands the intent of this recommendation but does not agree with its absolute form. The wording of the recommendation reflected its time and was prior to the 1995 Standards Australia AS/NZS4360 Risk Management Standard. CASA also understands that the use of the absolute "never" is not consistent with current ATSB practice.
To accept the absolute form of the recommendation would require the allocation of Class D or higher airspace wherever scheduled services operate. This would result in an allocation of resources that is not commensurate with risk.
ICAO Class E and G airspace specifically has no radio requirement for VFR aircraft. ICAO has introduced both of these classifications with the full knowledge of the limitations of see-and-avoid. ICAO makes no recommendation in relation to scheduled services not operating in these airspace classifications.
Overly discounting the effectiveness of see-and-avoid and devising unique procedures has itself led to unintended consequences that are unresolved. Pilots may scan significantly less and become over reliant on radio alerting through a concept known as diffusion of responsibility. The BASI report RP/93/01 (December 1993) and the continuing incident reports that are being filed listing near misses in mandatory radio Class E and G airspace may support this concern. CASA believes that radio alerting is only effective when the alerting area is small with readily identifiable reporting points so that the alert is specific.
Extracts from United States Research:
(http://www.aviation.uiuc.edu/UnitsHF...n03/talwic.pdf)
With regard to the major issue addressed in this study, scanning strategies, the current data appears to be the first to document the effectiveness of certain scanning strategies, as measured through eye-movements, and their effectiveness measured through traffic detection performance. In this regard, it is important to note that the FAA-recommended sector scan comes up as a clear winner over all others, including slightly better performance than the recommended sweep strategy, availing increased Outside World (OW) scanning, and less disruption with flight control. The sector scan also appeared to be encouraged by the auditory condition and this auditory condition was itself associated with somewhat better traffic detection. Furthermore, this strategy is coupled with more total OW scan time (although this proportion still did not approach the FAA recommended values).
It appears that whatever strategy is generally adopted, the appearance of a cue, whether visual (CDTI) or auditory, often served to preempt that strategy, to bring scanning into the region where the traffic is expected to be seen. This qualitatively different .find cued traffic. scan pattern seems to be fairly uniform across all pilots, but may leave them vulnerable for detecting a second, unexpected traffic aircraft that might appear after the cue is presented, an observation described by Harris (1979) in traffic detection, and observed as a statistically robust consequence of cueing in both freeflight scanning (Wickens, Helleberg, & Xu, 2002), and in other target detection domains (Yeh, Wickens, & Seagull, 1999; Yeh & Wickens, 2001).
THE RESULTS HAVE ALSO SHOWN THAT CUEING OR ATTENTION GUIDANCE, PROVIDED IN EITHER MODALITY, APPEARS TO MAINTAIN DETECTION PERFORMANCE AT A LEVEL OF AROUND 90%, CLEARLY BETTER THAN THE UN-CUED RATE OF AROUND 60% REVEALED IN OTHER STUDIES, AS PREVIOUSLY MENTIONED, IN BOTH SIMULATED (WICKENS, HELLEBERG, & XU, 2002) AND REAL FLIGHT (MARSHALL & FISHER, 1959) ENVIRONMENTS. NEVERTHELESS, IT IS IMPORTANT TO NOTE THAT THIS DETECTION LEVEL STILL REMAINS FAR FROM PERFECT, AND APPEARS TO BRING WITH IT A COST OF SOME ATTENTIONAL TUNNELING.
Finally, we note that the overall ratio of OW to inside scanning (slightly less than 1:2), as observed in prior research (Harris, 1979; Wickens et al., 2002), is one that departs from FAA guidelines to favor the OW. Even though all three modality conditions in this study had other sources of traffic cueing information (ATC, CDTI, or both), parallel studies where these resources were not available (Wickens, Helleberg & Xu, 2002), have shown that the optimal ratio was still not found.
The second last paragraph indicates that unalerted see and avoid may be as much as 50% less effective than alerted see and avoid.
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Umm, VoR, you might want to edit your mathematical calculations to preserve credibility.
Shouldn't that be "The second last paragraph indicates that unalerted see and avoid may be as much as 33% less effective than alerted see and avoid" ?
Not quibbling with the reported research, just the sums....
Fly safely
Shouldn't that be "The second last paragraph indicates that unalerted see and avoid may be as much as 33% less effective than alerted see and avoid" ?
Not quibbling with the reported research, just the sums....
Fly safely
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NOtim TAMS,
Our apologies.
You are correct.
We actually meant to state that the information provided would seem to indicate that alerted see and avoid may be 50% more effective than unalerted see and avoid.
Our apologies.
You are correct.
We actually meant to state that the information provided would seem to indicate that alerted see and avoid may be 50% more effective than unalerted see and avoid.
