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Comments on the Issues that the Proposals Seek to Address
See para 2.2.5 in document
Issue 1: Replacement of 'Classical' SSR
Whilst the replacement of classical SSR was essential for Commercial Air Transport flying aircraft in crowded Class A airspace, it is not necessary for GA aircraft in Class G airspace. The document lists 4 reasons why SSR should be replaced with Mode S in Class G airspace:
a. Shortage of SSR Codes in Europe. Although there is a shortage of SSR Mode 3 discrete codes available in Europe, VFR traffic in class G airspace does not use discrete codes. Therefore the continued use of existing SSR equipment has absolutely no effect on this issue. VFR aircraft will never delay commercial flights. This is not a relevant issue and must be removed from the RIA
b. Economic Benefits For ATS Providers Will Not Be Maximised. The fact that ATS providers will need to upgrade their SSR interrogators to cope with increased volumes of CAT aircraft fitted with Mode S is not a reason force non-CAT aircraft to replace existing transponders. There is no safety or economic benefit available to be had from such aircraft “to maximise the investment of the ATS providers”. This is a completely irrelevant issue that does not require replacement of classical SSR equipments by 2008. It must be removed from the RIA
c. Transponder Responses Overlap. The issue of traffic density leading to overlapping SSR indications on controller displays within controlled airspace is a problem related to CAT aircraft in terminal areas, in holding areas and at busy commercial airports. Once again this is solely a CAT issue and has nothing whatever to do with non-CAT aircraft flying in Class G airspace. The concluding statement that therefore Mode S must be fitted (to non-CAT aircraft in Class G airspace) is patently untrue. It must be removed from the RIA
d. Interference. The suggestion that Mode S must be fitted to all aircraft to prevent interference and maintain frequency integrity is a patently false statement. An aircraft with no SSR caused no interference at all. Therefore not fitting Mode S to an aircraft that does not have SSR does not cause interference. Phasing out existing SSR equipment installed in non-CAT aircraft will not have any effect on interference as they do not operate in congested terminal areas and stacks. This statement must be removed entirely from the RIA.
Issue 1 has no relevance to GA operations in Class G airspace. Therefore aircraft with existing Mode A and C transponders should not have to replace them.
Issue 2: Need to Improve Collision Avoidance Measures
We support all appropriate measures to minimise the risk of collisions but we will not countenance a proposal being dressed up as improving safety when logic says it does the opposite.
The paper notes that the vast majority of airproxes occurred below 3000ft in class G airspace. But fitting SSR to GA and S&RA aircraft produces no mutual anti-collision benefit. Moreover, most military fast jets do not have ACAS so are not affected either. So, the only class of aircraft that can benefit substantially from improved collision avoidance as a result of the proposal is CAT.
Statistics show that 40% of airproxes did not involve GA at all. Therefore the great majority of these must have been inter-CAT aircraft airproxes involving significant risk to life. As these aircraft already carry SSR and ACAS, it appears that the introduction of SSR will have little effect on the risk to life and property in the majority of encounters. This matter should be analysed properly or removed from the RIA. You may want to look at the table of Airmiss data we have prepared for you.
2.2.6 a.
Table 1 (see page 5 in the document) sets out the proportion of sighting issues in airproxes but what it actually tells us is that CAT does not use visual sighting for avoidance and GA and military pilots do. So when an airprox occurs, the failure is linked to the method of separation in use. This has no relevance to the RIA and should be removed. Collision warning systems have positive benefits for the type of aircraft that normally carry them but that is not what is proposed here so this is irrelevant and should be removed.
The paper makes reference to airspace segregation almost as a threat but this style has no place in a safety case. It may be that some segregation is necessary to achieve the appropriate level of safety. If it is and we agree, we will support it. However, as has already been stated, the majority of airproxes occur between GA aircraft in class G airspace below 3000ft. Introducing additional restricted airspace will increase the traffic density for this group of aircraft so increasing the risk of collision, Mode S having no inter-aircraft effect within the group. Therefore this threat would be contrary to the objective of the RIA and must be removed.
2.2.6 b.
The concept of using SSR mode C to mitigate potential airspace infringements is very interesting. But there are other ways to deal with this. This is a side issue that is not related to the objective of the RIA and as such must be removed.
2.2.6 c.
The issue of increasing CAT movements at regional airports is important, as it is the only area where CAT should come into contact with GA aircraft and it is actually the only area where SSR is relevant in improving safety. However the consultation mostly lists airfields that already have controlled airspace and these are not relevant. It may be that transponders should be carried by all aircraft near the approach to other regional airports but that is not considered.
2.2.6 d.
Conspicuity of gliders would be improved using SSR but in most cases the mass of responses would overwhelm controllers. Again this is only relevant close to regional airports.
2.2.6 e.
Mandating SSR to support a TPAS system which is not mandated is not logical or cost effective. In fact very few GA aircraft carry TPAS. Future collision warning systems in light aircraft are much more likely to be based on ADS-B because it provides accurate lateral indication whereas Mode S does not. Light aircraft do not normally have sufficient performance to avoid in the vertical as required by TCAS/Mode S systems.
2.2.6 f.
Military collision warning systems are not being mandated by 2008 so it is false logic to mandate SSR to support them.
Mode S is not required to interact with ACAS, Mode C is required so existing SSRs satisfy the requirement. It is thus a false conclusion to say that mode S is needed for this.
Issue 3: International Obligations and Co-operation
ICAO does not specify SSR for gliders, hang gliders, powered parachutists etc. Nor does it specify Mode S. Therefore replacement of existing transponders is not required.
Other nations have introduced transponder areas where appropriate. This seems sensible.
ICAO does not specify Mode S so existing transponders need not be replaced to comply.
It said that contiguous Mode S coverage is necessary but that is only for international flights by CAT aircraft. It is irrelevant to Class G airspace.
It is false to suggest there is a European programme to introduce mode S into Class G airspace. There is none. The important text in relation to this is:
However, these will not legislate for the carriage and operation of SSR transponders on aircraft, and appropriate mandates in this regard are not currently being muted. The SES initiative is still somewhat embryonic and the work programme has to be prioritised within available resources. Indeed, the initial SES rules are likely to just support existing programmes and projects.
And
The UK policy proposal contained within this Regulatory Impact Assessment (RIA) is, therefore, complementary to foreseen future SES requirements for SSR transponder carriage
Issue 4: Support for Future Surveillance Technology
2.2.8.
As the UK has no immediate plans to implement ADS-B it might be sensible to advise that when a transponder is purchased, the owner should consider making provision for future operation of ADS-B. It makes no sense to mandate in 2008, I system which is not yet supported.
Issue 5: Efficiency of the Use of Lower Airspace
2.2.9
Making temporary airspace reservations is not new and happens now.
Permanent segregation is what we have now. Again mode S is irrelevant. So is ADS-B. The requirement here seems to be for a means to detect airspace infringements.
Issue 6: Integration of UAV Operations
2.2.10
CAA UAV policy is that UAVs must be able to see and avoid without the use of ACAS. Therefore Mode S as such is not relevant. UAVs are a commercial issue and any costs would need to be borne by the commercial operators fooling a specific consultation on the matter
Issue 7: Impact of Wind Turbines on Aviation
2.2.11
There is currently no requirement for primary radars to detect GA aircraft in class G airspace. Mode S not relevant. Existing SSR transponders will do. 2008 is not a cut off line
Issue 8: Spectrum Availability for Primary Radar
2.2.12
The suggestion that somehow we need to buy Mode S so primary radars can be shut down is nonsense in the 2008 timeframe. Primary radars are required for security issues and for failure cases.
Additional Comments:
Para 2.2.1 says one of the reasons for Mode S is to” the general surveillance of aircraft in all UK airspace”. We do not know what this is but we would like it to be set out in a policy statement so it is understood by all. Some seem to think this is a mechanism for Government to introduce charging for the use of class G airspace. Others, that this is a mechanism for collecting evidence of misdemeanour. It does not seem to have any connection with interoperability and we can find no supporting argument for it in the paper. It needs to be explained and if it is part of the reason for mandating mode S transponders, this needs to be stated. If not it must be removed.
As we understand it there is no intention that UK airspace can be shared by all users as is stated in Para 2.2.1. We understand that it is proposed that airspace currently available for recreational, sport and GA activity will in the future be used for commercial purposes. Aircraft that currently use Class G airspace will not be afforded access to airspace currently reserved for commercial and national purposes. Therefore this part of the discussion must be removed.
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