Carriage and Use of Notice of Final Rule Making ADS-B Avionics
A respondent stated that aircraft GNSS receivers have common technical standards (TSOs) but user controls and operation is not standardised; each manufacturer has a different approach. For ADS-B, standards for equipment should cover not only the performance but also the ergonomics of operation.
An individual stated that the inclusion of “another system acceptable to CASA” would allow CASA to approve other ADS-B systems without reference to any standard whatsoever. This can lead to undesirable consequences including Australian-only approvals of sub-standard designs and preferential treatment. This type of arbitrary discretion should not be permitted by a regulator. CASA should either state the standards it will apply in approving other systems or remove the paragraphs from the CAO. 

CASA’s response
CASA has closely considered the standards in TSO-C166 and TSO-C166a and has concluded that, for Australian operational use, both TSO-C166 and TSO-C166a are acceptable standards. See technical explanatory material in the Background section (section 1 of the main body of this NFRM).
It is possible that there will be other equivalent ADS-B avionics equipment standards which will also be acceptable to CASA, for example the corresponding EASA/JAA standard which it is understood will be issued shortly. This is the reason why CASA has included a clause within the CAO to be able to approve other ADS-B transponder standards without having to go through a protracted regulatory change process for every new, equivalent ADS-B standard that is established throughout the world.
CASA considers it to be impractical and prescriptive for it to establish regulatory based performance standards which cover all possible present and future developments. Outcome-based regulation needs to provide for CASA to be responsive to technical developments without having to go through a protracted process of legislative rule amendments.
As with the standards for navigation source equipment, the guidance material in AC 21-45 will include an up-to-date listing of equivalent acceptable standards for ADS-B avionics.
Disposition
In the final rule CAO 20.18:
x
Paragraph 9B.2 has been reworded as follows:
“9B.2(a) ADS-B transmitting equipment carried by an aircraft for operational use in Australia must comply with Appendix XI.
9B.2(b) Non-compliant ADS-B transmitting equipment carried by an aircraft must be deactivated whilst the aircraft is within Australia.”
Page A8 Document NFRM 0601AS

Notice of Final Rule Making
x  Sub-paragraph 1(a) of Appendix XI (that specified “TSO-C166 as in force on 20 September 2004”) has been retained as a standard. A new sub-paragraph 1(b) has been added as follows: “TSO-C166a as in force on 21 December 2006”. Accordingly, both TSO-C166 and TSO-C166a are acceptable standards for ADS-B transmitting equipment.  
x  Paragraph 1(d) of Appendix XI has been retained to allow for CASA to approve other standards for ADS-B transmitting equipment that are acceptable to CASA for operational use in Australia. 

COMMENT 5: DEFINITION OF ADS-B IN DRAFT CAO 20.18 AMENDMENT
An organisation submitted that in subsection 9B of the proposed CAO 20.18 amendment, there is no explicit definition of the applicability of Appendix XI. “ADS-B” appears to be self-defined leaving a legal loophole and the entire CAO amendment ineffective. The CAO just states “ADS-B transmitting equipment” without any specific definition of what that means, other than an implication in Appendix XI that ADS-B equipment is equipment that meets TSO-C166. If that is the case then any equipment that does not meet TSO-C166, regardless of whether the extended squitter is active or not, is not obligated to meet the CAO requirement, i.e. TSO-C166. This could be improved by possible inclusion of “1090 MHz Extended Squitter” as the definition of ADS-B with an appropriate definition of 1090 MHz ES also included, overcoming the doubt on applicability of the rule.
　
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