4.1 Defence aircraft operate in a global airspace environment that includes civil airspace that is subject to prescribed access criteria. This airspace is a shared resource and, to maintain airspace limitations such as separation minima, civil airworthiness authorities prescribe minimum performance requirements for aircraft navigation systems. While International Civil Aviation Organisation (ICAO) rules for civil aviation are not applicable to State registered aircraft, it is becoming increasingly difficult for civil air traffic authorities to cater for Defence aircraft if they are not capable of similar navigation performance to civil aircraft. This may result in Defence aircraft being subjected to civil airspace restrictions, for example sub-optimal altitudes and routing and, in some instances, exclusion from certain airspace (despite the ICAO exemption).
4.2 Some civil operations, such as operations under Instrument Flight Rules (IFR), require compliance with specific airworthiness requirements for aircraft equipment and/or operations. Where Defence aircraft require unimpeded access to civil airspace subject to IFR, the Defence aircraft must satisfy an equivalent level of safety to civil aircraft operating in the airspace to avoid posing a risk to other airspace users. Further, Defence operations under the same conditions as civil IFR operations, whether in designated airspace or not, should endeavour to satisfy the same (or substantially similar) requirements to afford a level of safety for Defence aircraft crew and passengers commensurate with these type of operations.
4.3 DASR RoA.05, Rules of the Air, requires capability managers to ‘ensure that Rules of the Air as they apply to Defence Aviation as stipulated within Defence AIP are harmonised with ICAO and national civil practice wherever practical in order to assure Defence Aviation interoperability with non-Defence aviation activities’. To verify that Defence aircraft designs satisfy the requirements for operating in civil airspace (eg to operate on Performance Based Navigation (PBN) routes or conduct operations under IFR), the Authority prescribes airworthiness design requirements for navigation systems. Where shortfalls are identified against the ‘essential’ Authority prescribed design requirements in this chapter (eg to accommodate military unique functions), but the Defence aircraft navigation system is expected to substantially meet the relevant standard, the Authority must be petitioned for a determination regarding the shortfalls.
4.4 This Chapter presents Authority prescribed airworthiness design requirements for Defence aircraft navigation systems. Importantly, the airworthiness design requirements in this chapter are not suitable for application in isolation from an Airworthiness Code. The Authority’s requirements for the application of recognised Airworthiness Codes are defined in Section 1 of this manual. Further, there may be additional airspace access requirements (such as requirements for communications and display systems) related to operations in civil airspace that must be considered when establishing the suitability of an aircraft to operate in that airspace. Where applicable, compliance with these additional requirements must also be verified.
4.5 The determination of whether a Defence aircraft requires particular navigation systems capabilities is, ultimately, a capability and safety decision for the capability manager. Where the capability manager determines that unimpeded operations in civil airspace or along specified civil routes are required, navigation systems must meet the requirements prescribed for navigation in that airspace. Prior to establishing the airworthiness design requirements that must be met for a Defence aircraft’s navigation system, the global airspace and navigation environment in which the Defence aircraft will operate must be identified to support the establishment of navigation systems requirements necessary to achieve safe aircraft operations. This section presents the Authority prescribed navigation systems design requirements for Defence aircraft.
4.6 Civil airspace separation minima (from other aircraft in the area and from obstacles along the route) are predicated on the aircraft’s ability to navigate to a predetermined accuracy threshold, or to advise the crew when this accuracy is not available so that air traffic controllers can make alternative separation arrangements. Defence aircraft operations in PBN designated airspace may present a risk to other airspace users, and to the Defence aircraft itself, if the aircraft is unable to maintain the required navigation performance and neither air traffic controllers nor other airspace users are aware of this performance limitation. Consequently, to permit Defence aircraft operations that are compatible with, and safely support interoperability in, civil PBN airspace, the Authority prescribes Area Navigation (RNAV) / Required Navigation Performance (RNP) airworthiness design requirements based on the associated civil standards. Where a Defence aircraft requires unimpeded access to civil airspace for which a PBN specification applies, the airworthiness design requirements associated with the relevant PBN specification, and prescribed by an Authority recognised NAA, apply.
4.7 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to RNP 10 designated airspace, the navigation system must satisfy the performance and functional requirements prescribed by any one of the following:
CASA AC 91U-2(0), Required Navigation Performance 10 (RNP 10) Operational Authorisation, or
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems, or
EASA AMC 20-12, Recognition of FAA Order 8400.12A for RNP-10 Operations.
4.8 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to RNAV 5 designated airspace, the navigation system must satisfy the performance and functional requirements prescribed by any one of the following:
CASA AC 91.U-01, Navigation Authorisations, or
FAA AC 90-96A, Approval of U.S. Operators and Aircraft to Operate Under Instrument Flight Rules (IFR) in European Airspace Designated for Basic Area Navigation (B-RNAV) and Precision Area Navigation (P-RNAV), or
EASA AMC 20-4A, Airworthiness Approval and Operational Criteria for the Use of Navigation Systems in European Airspace Designated For Basic RNAV Operations.
4.9 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to RNAV 1 and/or RNAV 2 designated airspace, the navigation system must satisfy the performance and functional requirements prescribed by any one of the following:
CASA AC 91.U-01, Navigation Authorisations, or
FAA AC 90-100A, U.S Terminal and En Route Area Navigation (RNAV) Operations, or
JAA TGL 10, Airworthiness and Operational Approval for Precision RNAV Operations in Designated European Airspace.
4.10 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to RNP 4 designated airspace, the navigation system must satisfy the performance and functional requirements prescribed by either of the following:
CASA AC 91U-3(0), Required Navigation Performance 4 (RNP 4) Operational Authorisation, or
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems.
4.11 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to RNP 1 and/or RNP 2 designated airspace, the navigation system must satisfy the performance and functional requirements prescribed by either of the following:
CASA AC 91.U-01, Navigation Authorisations, or
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems.
4.12 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to Advanced RNP (A-RNP) airspace, the navigation system must satisfy the performance and functional requirements prescribed by the following:
CASA AC 91.U-01 Navigation Authorisations, or
FAA AC 20-138D Airworthiness Approval of Positioning and Navigation Systems.
4.13 Design Requirement (Essential). Where Defence aircraft operation on a defined RNP Approach (RNP APCH) route is required, the navigation system must satisfy the performance and functional requirements prescribed by any one of the following:
CASA AC 91.U-01, Navigation Authorisations, or
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems, or
EASA AMC 20-27A, Airworthiness Approval and Operational Criteria for RNP APPROACH (RNP APCH) Operations Including APV BARO-VNAV Operations.
4.14 Design Requirement (Essential). Where Defence aircraft operation on a defined RNP Authorisation Required Approach (RNP AR APCH) route is required, the navigation system must satisfy the performance and functional requirements prescribed by any one of the following:
CASA AC 91.U-01, Navigation Authorisations, or
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems, or
EASA AMC 20-26, Airworthiness Approval and Operational Criteria for RNP Authorisation Required (RNP AR) Operations.
4.15 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to RNP 0.3 designated airspace, the navigation system must satisfy the performance and functional requirements prescribed by either of the following:
CASA AC 91.U-01, Navigation Authorisations, or
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems.
NOTES
Compliance with the requirements of one navigation specification does not automatically verify compliance with the requirements of all other navigation specifications with less stringent accuracy requirements (eg compliance with RNP 1 does not verify compliance with RNP 4). Notwithstanding the above ‘note’, where a Defence aircraft satisfies the requirements for A-RNP operations, then the aircraft is also capable of conducting RNAV 5, RNAV 2, RNAV 1, RNP 2, RNP 1 and RNP APCH operations. However, demonstration of RNAV 5, RNAV 2, RNAV 1, RNP 2, RNP 1 and RNP-APCH, in combination, does not automatically equate to A-RNP. Additional functions, such as Radius to Fix (RF) Path Terminator that are optional for other RNP specifications, are required for A-RNP.
4.16 Required Vertical Separation Minimum (RVSM). RVSM describes the reduction of standard vertical separation to 1000 feet for aircraft flying above Flight Level (FL) 290 in designated RVSM airspace. Defence aircraft operating in designated RVSM airspace with a navigation system that does not provide the required performance or functionality to support such operations may pose a hazard to other airspace users as a result of loss of separation assurance. Therefore, Defence aircraft that are not RVSM compliant and have a requirement to operate in RVSM designated airspace may be subjected to limitations on their use of that airspace (eg limited to operations only during low volume civil traffic periods, or restrictions on Flight Level). To permit Defence aircraft operations that are compatible with, and safely support interoperability in, civil RVSM airspace, the Authority prescribes RVSM airworthiness design requirements based on the associated civil NAA standards.
4.17 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to Reduced Vertical Separation Minimum (RVSM) designated airspace, the navigation system must meet the requirements prescribed by any one of the following:
CASA CAAP 181A-1 (2), Reduced Vertical Separation Minimum (RVSM) Approvals, or
FAA AC 91-85B, Authorization of Aircraft and Operators for Flight in Reduced Vertical Separation Minimum Airspace, or
EASA CS-ACNS, Certification Specifications and Acceptable Means of Compliance for Airborne Communications, Navigation and Surveillance.
4.18 Vertical Navigation (VNAV). VNAV is used in conjunction with RNAV/RNP lateral approach procedures to define requirements for the vertical flight paths and vertical tracking to the path of instrument approaches. VNAV is conducted using either barometric vertical navigation (baro-VNAV) equipment, or via GPS equipment with Satellite Based Augmentation System (SBAS) capability. Circa 2021, SBAS is not available in Australian controlled airspace (Geoscience Australia has initiated an SBAS project due for completion in 2023/24). Defence aircraft cannot conduct a VNAV approach unless the aircraft is fitted with a navigation system that supports VNAV capability. VNAV systems that do not provide the required performance or functionality may result in aircrew loss of situational awareness, descent below minima and, ultimately, CFIT.
4.19 Design Requirement (Essential). Where Defence aircraft operation on a defined Vertical Navigation (VNAV) approach is required, the navigation system must meet the requirements prescribed by the following:
Baro-VNAV.
CASA AC 91.U-01, Navigation Authorisations, or
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems, or
EASA AMC 20-27A, Airworthiness Approval and Operational Criteria for RNP APPROACH (RNP APCH) Operations, including BARO-VNAV Operations.
GPS supported VNAV.
FAA AC 20-138D, Airworthiness Approval of Positioning and Navigation Systems, or
EASA AMC 20-28, Airworthiness Approval and Operational Criteria related to Area Navigation for Global Navigation Satellite System approach operation to Localiser Performance with Vertical guidance minima using Satellite Based Augmentation System.
4.20 Design Requirement (Essential). Database data for navigation of Defence aircraft must be provided by accredited suppliers, approved in accordance with applicable Authority recognised NAA regulations or DASR ANSP.
4.21 All RNAV/RNP applications use aeronautical data to define ground-based navigation aids, runways, gates, waypoints and route/procedure to be flown. The safety of RNAV/RNP operations is dependent upon the precision, resolution, and integrity of this data. Further information on the use and approval of Aeronautical Information Databases is contained in Section 5 Chapter 3, Mission Planning Systems.
4.22 Civil NAAs publish airworthiness requirements for the conduct of flights under Instrument Flight Rules (IFR). These requirements describe both aircraft systems and aircrew competency and authorisation. Defence aircraft systems and equipment requirements for IFR operations should satisfy airworthiness design requirements that support safe operations when reliance on visual flight cues is not possible. The IFR requirements of Authority recognised civil NAAs provide a widely accepted benchmark for aircraft systems used to support safe IFR operations. Consequently, the Authority prescribes IFR design requirements for Defence aircraft based on the civil IFR requirements. Where a Defence aircraft requires unimpeded access to civil airspace in which IFR applies, the relevant airworthiness design requirements prescribed by an Authority recognised civil NAA must be satisfied.
4.23 Authority recognised NAAs have promulgated IFR certification and approval requirements based on aircraft categories and types of operations, which may not be representative of the aircraft types operated by the ADF or the roles in which these aircraft are employed. Therefore, the application of the NAA requirements to Defence aircraft may not be straightforward. The IFR airworthiness design requirements prescribed in this chapter are presented using the generic aircraft type categories used within civil type certification programs (ie Parts 23, 25, 27 and 29 aircraft types and military equivalents). Consequently, the correct aircraft ‘category’ must be established for a particular Defence aircraft to identify which Authority prescribed design requirements are applicable.
4.24 Design Requirement (Essential). Where a Defence aircraft requires unimpeded access to IFR designated airspace, the aircraft must satisfy the airworthiness design requirements prescribed by an Authority recognised civil NAA for the applicable aircraft category as follows:
Part 23 (and military equivalent) certified Defence aircraft – single/dual pilot and less than 9 passengers.
FAA. IFR certification/approval requirements detailed in FAR Part 23 and FAR 91.205, supplemented with:
fitment of a landing light(s), and
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications, or
EASA. IFR certification/approval requirements detailed in EASA CS-23 and EU CAT IDE.A.115, IDE.A.130, IDE.A.135, IDE.A.325, IDE.A.335, IDE.A.345 and IDE.A.350, supplemented with:
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications.
Part 25 (including Part 23 commuter/charter and military equivalent) certified Defence aircraft – dual pilot and/or 9 or more passengers/crew.
FAA. IFR certification/approval requirements detailed in FAR Part 25 (and relevant sections of FAR Part 23 applicable to commuter category aircraft) and applicable requirements from FAR 91.205, 121.323, 121.325, 121.349, 125.203, 125.205, 135.163 and 135.165, supplemented with:
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications, or
EASA. IFR certification/approval requirements detailed in EASA CS-25 and EU CAT IDE.A.130, IDE.A.135, IDE.A.325, IDE.A.335, IDE.A.345 and IDE.A.350, supplemented with:
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications.
Part 27 (and military equivalent) certified Defence aircraft – single/dual pilot and less than 9 passengers.
FAA. IFR certification/approval requirements detailed in FAR Part 27 (including FAR 27 Appendix B) and FAR 91.205, supplemented with:
fitment of a landing light(s); and
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications, or
EASA. IFR certification/approval requirements detailed in EASA CS-27 (including CS-27 Appendix B) and EU CAT IDE.H.115, IDE.H.130, IDE.H.135, IDE.H.335, IDE.H.345 and IDE.H.350, supplemented with:
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications.
NOTE
The requirements for static pressure sources defined in CASR Part 91 Manual of Standards may be used in lieu of those defined in FAR Part 27 Appendix B or EU CAT.IDE.H.130.
Part 29 (including Part 27 commuter/charter and military equivalent) certified Defence aircraft – dual pilot and/or 9 or more passengers/crew.
FAA. IFR certification/approval requirements detailed in FAR Part 29 (including FAR 29 Appendix B) and FAR 91.205, 135.163 and 135.165, supplemented with:
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications, or
EASA. IFR certification/approval requirements detailed in EASA CS-29 (including CS-29 Appendix B) and EU CAT IDE.H.115, IDE.H.130, IDE.H.135, IDE.H.160, IDE.H.335, IDE.H.345 and IDE.H.350, supplemented with:
equipment and systems requirements prescribed in the ADF General Planning Australia (GPA) and Flight information Handbook Australia (FIHA) publications.
NOTE
The requirements for static pressure sources defined in CASR Part 91 Manual of Standards may be used in lieu of those defined in FAR Part 29 Appendix B or EU CAT.IDE.H.130
NOTE
While the airworthiness design requirements in the civil Airworthiness Codes described above provide the benchmark IFR design requirements for Defence aircraft, Defence operational requirements such as those defined in the ADF GPA and FIHA may override the minimum equipment and systems prescribed by civil NAAs.
4.25 VOR navigation systems provide a ground-based radio navigation aid infrastructure that may be used for navigation when GPS or other independent navigation sources are unavailable. ILS provides a ground-based radio navigation approach aid to guide an aircraft down a predetermined safe approach path to the runway threshold. Both of these systems support safe operations in certain PBN designated airspace and safe landing in adverse weather conditions at airfields around the globe. Consequently, the Authority prescribes VOR and ILS design requirements to define the required level of performance when used for these operations in Defence aircraft.
4.26 Design Requirement (Essential). VOR receivers fitted to Defence aircraft must satisfy the requirements of:
TSO-C40c VOR Receiving Equipment Operating Within the Radio Frequency Range of 108-117.95 Megahertz (MHz), or
ETSO-2C40c VOR Receiving Equipment Operating Within the Radio Frequency Range of 108-117.95 Megahertz (MHz).
4.27 Design Requirement (Essential). ILS receivers fitted to Defence aircraft must satisfy the requirements of:
TSO-C34e, ILS Glide Slope Receiving Equipment Operating within the Radio Frequency Range of 328.6-335.4 Megahertz (Mhz) and TSO-C36e Airborne ILS Localizer Receiving Equipment Operating Within the Radio Frequency Range of 108-112 Megahertz (MHz), or
ETSO-2C34f ILS Glide Slope Receiving Equipment Operating within the Radio Frequency Range of 328.6-335.4 Megahertz (Mhz), and ETSO-2C36f Airborne ILS Localizer Receiving Equipment Operating Within the Radio Frequency Range of 108-112 Megahertz (MHz).
4.28 The performance of VOR and ILS systems used to support PBN and ILS operations may be adversely affected by external radio frequency transmissions. Operations in certain airspace regions around the globe (in particular Europe, Africa, Russia and the Middle East) may expose Defence aircraft VOR and ILS navigation systems to an increased risk of FM interference from civil radio stations. Compliance with the standards prescribed in paragraphs 4.27 and 4.28, inherently covers FM immunity for Defence aircraft VOR and ILS.
4.29 Further guidance on implementing the navigation systems design requirements prescribed in this chapter can be provided by the chapter sponsor.