Table of Contents (Continued)
Appendix 1. GPS Oce
anic/Remote NavigationA1-1
A1-1. GPS Oceanic/Remote NavigationA1-1
A1-2. Approval ProcessA1-1
A1-3. Equipment Performance. ................................................................................................. A1 -2
Appendix 2. RNP AR OperationsA2-1
A2-1. IntroductionA2-1
A2-2. Performance Requirements.............................................................................................. A2- 2
A2-3. RNP AR General RequirementsA2-4
A2-4. Requirements for RNP AR Approaches with RF LegsA2-15
A2-5. Requirements for RNP AR Approach values less than 0.3A2-15
A2-6. Requirements for Approaches with a Missed Approach Less Than RNP 1A2-15
A2-7. Navigation Data Va lidation ProgramA2-17
A2-8. Installation Considerations for RNP ARA2-20
Appendix 3. RNP Advanced FeaturesA3-1
A3-1. IntroductionA3-1
A3-2. Radius to Fix Leg Capability........................................................................................... A3 -1
Appendix 4. GNSS Tests to Support ADS-BA4-1
A4-1. IntroductionA4-1
A4-2. Velocity Accuracy and Veloc ity Figure of Merit TestsA4-1
A4-3. Horizontal Velocity Accuracy Test Conditions Commensurate with NACV = 1A4-2
A4-4. Horizontal Accuracy Pa ss/Fail DeterminationA4-4
A4-5. Horizontal Velocity Figure of Merit Pass/Fail DeterminationA4-4
A4-6. Vertical Velocity Accuracy Test Conditions Commensurate with NACV = 1A4-5
A4-7. Vertical Velocity Accuracy Pass/Fail DeterminationA4-7
A4-8. Vertical Velocity Figure of Merit Pass/Fail DeterminationA4-7
A4-9. Additional Tests to Demonstr ate Accuracy Commensurate with NACV = 2A4-8
A4-10. Test to Demonstrate HAE Output and Vertical Position Accuracy MetricA4-9
A4-11. Test to Demonstrate Horizontal Position Accuracy MetricA4-10
A4-12. Demonstrating True Track Angl e/True Track Angle ValidityA4-11
Appendix 5. Sample Airplane/Rotorcraft Flight Manual SupplementA5-1
A5-1. IntroductionA5-1
Appendix 6. Installation of GNSS Equipment for VFR Use OnlyA6-1
A6-1. IntroductionA6-1
A6-2. GeneralA6-1
A6-3. ApplicabilityA6-1
A6-4. Technical InstructionsA6-1
Appendix 7. Definitions and AcronymsA7-1
A7-1. DefinitionsA7-1
vii
viii Table of Contents (Continued)
A7-2. AcronymsA7-3
Appendix 8. Related DocumentsA8-1
A8-1. FAA Advisory Circulars.................................................................................................. A 8-1
A8-2. FAA Technical Standard OrdersA8-3
A8-3. RTCA, Inc. Documents (RTCA/DO) documentsA8-4
A8-4. Other DocumentsA8-5
A8-5. How to Get Related DocumentsA8-6
List of Tables
Table 1. Effective Noise Density for All GNSS Sources18
Table 2. Acceptable Standard Antennas29
Table 3. DME Usable Range33
Table 4. 2D Accuracy Requirements for Equipment Usin g a Single Co-located VOR/DME39
Table 5. Error Elements40
Table 6. Vertical Path Performanc e Limit for Baro-VNAV64
Table 7. Vertical Path Deviations65
Table 8. Typical Hazard Classifications68
Table 9. RNP FTE Performance99
Table 10. INS/IRU Accuracy After Loss of Radio Updating115
Table 11. Tailwind Component (VKTW) for Turn CalculationsA2-8
Table 12. Platform Dynamics for Horiz ontal Velocity Accuracy TestA4-3
Table 13. Platform Dynamics for Vertical Velocity Accuracy TestA4-6
List of Figures
Figure 1. Minimum Straight Path Before DAA2-17
Chapter 1. General In formation.
1-1. Purpose.
This advisory circular (AC) provides guidance m aterial for the airworthiness approval of installed positioning and navigation equipment. Positioning and navigation equipment may be used for a variety of functions such as navigation, automatic dependent surveillance, and/or terrain awareness and warning systems. This AC addresses the following equipment:
a. Global positioning system (GPS) sensors or stand-alone navigation equipment, including those incorporating aircraft-based augmentation system (ABAS), satellite-based augmentation system (SBAS), or ground-based augmentation system (GBAS).
Note: For standardization within this document, the acronyms GPS/SBAS and GPS/GBAS are used to indicate SBAS augmenting GPS and GBAS augmenting GPS respectively.
b. Area navigation (RNAV) integrating data from multiple navigation sensors such as global navigation satellite system (GNSS), inertial reference units (IRU), and distance measuring equipment (DME).
c. RNAV intended for required navigation performance (RNP) operations, including advanced functions and RNP authorization required (AR) formerly referred to as special aircraft and aircrew authorization required (SAAAR).
Note: RNP AR was previously named RNP SAAAR. The name has been changed to RNP AR for international harmonization, but might not yet be standardized throughout all documents.
d. Barometric vertical navigation (baro-VNAV) equipment.
e. This AC does not address new satellite constellations that are planned or currently under construction. This AC will be updated when sufficient documentation exists to support multi-constellation equipment.
f. This AC incorporates the airworthiness considerations contained in AC 90-101A, Approval Guidance for RNP Procedures with AR, and AC 90-105, Approval Guidance for RNP Operations and Barometric Vertical Navigation in the U.S. National Airspace System, as a necessary first step to consolidating all the positioning and navigation equipment and RNP airworthiness guidance into one AC. Future AC 90-101 and AC 90-105 revisions will remove the airworthiness guidance. This AC will not replace the operational guidance found in the RNP 90-series ACs. However, this AC does replace the ACs listed in paragraph 1-3 by incorporating and updating the information they contained.
g. This AC is not m andatory and is not a regulation. This AC describes an acceptable means, but not the only means, to comply with applicable regulations.
h. This AC provides guidance information intended for new approvals. This AC is not intended to modify, change or cancel existing equipment design or airworthiness approvals.
Equipment with existing approvals can continue to be installed within the provisions of their original design and airworthiness certification.
i. The guidance in this AC cannot ensure compliance with Title 14 of the Code of Federal Regulations (CFR) parts 23, 25, 27, and 29 airworthiness regulations for every possible installation configuration. The applicant remains responsible for regulatory compliance and should work closely with their geographic aircraft certification office (ACO) to ensure regulatory compliance. Mandatory terms such as “must” used in this AC are only applicable when following the compliance method outlined.
j. In lieu of following this method without deviation, the applicant may elect to follow an alternate method, provided the alternate method is also found by the Federal Aviation Administration (FAA) to be an acceptable means of complying with the requirements of the federal aviation regulations 14 CFR.
1-2. Audience.
This AC is for aircraft m anufacturers, avionics manufacturers, installation shops, or other applicants seeking design and/or airworthiness approval for the positioning and navigation systems described in this document.
1-3. Cancellation.
a. This AC supersedes the ACs listed b elow. Equipment previously approved per the guidance in the superseded ACs is still valid for the operations and conditions stated in their approvals. The following documents are cancelled:
(1) AC 20-129, Airworthiness Approval of Vertical Navigation (VNAV) Systems for use in the U.S. National Airspace System (NAS) and Alaska.
(2) AC 20-130A, Airworthiness Approval of Navigation or Flight Management Systems Integrating Multiple Navigation Sensors.
(3) AC 20-138B, Airworthiness Approval of Positioning and Navigation Systems.
(4) AC 25-4, Inertial Navigation Systems.
b. This AC supersedes the airworthiness considerations in AC 90-45A, Approval of Area Navigation Systems for use in the U.S. National Airspace System. Equipment previously approved per the airworthiness guidance in AC 90-45A is still valid for the operations and conditions stated in their approvals.
1-4. Frequently Asked Questions.
This paragraph contains a list of questions that have been raised since AC 20-138B was first published. The responses to these questions are intended to help applicants interpret the guidance contained in this AC.
a. Ground Proxim ity Warning System/Terrain Awareness and Warning System (GPWS/TAWS) Mode 5 alert.
(1) Question: Is a GPWS or Class A TAWS Mode 5 alert a hard requirement to add localizer performance with vertical guidance (LPV) or GBAS landing system (GLS) capability?
(2) Answer: No. It is not the FAA’s intent to burden installers by changing the GPWS or TAWS functions; impacting the GPWS or TAWS technical standard order authorization (TSOA); or, requiring that either GPWS or TAWS become the only means to provide the function. The intent is to promote the GPWS/TAWS safety benefits by including a comparable alerting function during LPV or GLS approaches for deviations below glideslope.
Using the GPWS or TAWS Mode 5 alerting to provide the function is certainly acceptable, but is not required as the only acceptable method. See paragraphs 14-6.8 and 14-8.13 for clarification and additional guidance.
b. Using the term vertical navigation (VNAV).
(1) Question: Doesn’t RTCA/DO-229D assign a very specific meaning to the term ‘VNAV’ and dictate the term’s specific uses for SBAS-based vertical navigation?
(2) Answer: No. RTCA/DO-229D, section 2.2.1.1.7 provides a recommended usage for the ‘VNAV’ label, but only requires that the label be used in a consistent manner.
‘VNAV’ can be used for a lateral navigation/vertical navigation (LNAV/VNAV) approach procedure generated by GPS/SBAS-based or barometric-based vertical navigation capability (GPS/GBAS does not provide an LNAV/VNAV approach capability). The ‘VNAV’ label can also be used for an advisory vertical navigation function that provides vertical path deviation guidance indications on a non-essential, not-required basis. Refer to the following AC 20-138C chapters for additional information:
Chapter 4, Advisory Vertical Guidance;
Chapter 10, Baro-VNAV;
Chapter 11, section 11-8, General Human Factors Considerations;
Chapter 14, section 14-6.6, GPS/SBAS Equipment Annunciations; and, Chapter 17, section 17-5, Baro-VNAV integration with GNSS-Provided Vertical Guidance.
c. Tightly-coupled inertial navigation system/global positioning system (INS/GPS).
(1) Question: AC 20-138B, section 6-7 c. includes the following statement: "The FAA assumes that there is a limitation on the use of the GPS/inertial position data output to support enroute through lateral navigation (LNAV) approach only." Can you please explain the basis of this assumption? It appears to exclude the use of tightly coupled INS/GPS for oceanic use. Is this the intent? Or, is the intent to exclude it for use for LPV?
(2) Answer: Paragraph 6-6 addresses loosely-coupled systems and paragraph 6-7 addresses tightly-coupled systems. There is no intent to exclude either loosely-coupled or tightly-coupled INS/GPS from oceanic use. However, un-augmented GPS, even with tightlycoupled INS, is not adequate for vertical approach capability, and hybrid inertial vertical approach capability is not addressed in RTCA/DO-229D, appendix R. As stated in this AC, a GPS-based vertical approach capability requires GPS/SBAS or GPS/GBAS augmentation.
d. Flight management system (FMS) limitations.
(1) Question: AC 20-130A, section 5.d.(2) contained a limitation on FMS use and required an alternate means of navigation for the route flown. AC 20-138B does not include this section or make a mention of this limitation. What was the reasoning behind not including a similar section in AC 20-138B? Is there some higher level guidance that addresses this or is it left up to the safety analysis to address the need for an alternate means of navigation?
(2) Answer: It is important to differentiate between operational limitations and equipment performance limitations. AC 20-138C addresses equipment performance limitations while the 90-series ACs produced by Flight Standards address operational limitations (for example, 90-100, 90-101A, 90-105 for RNAV, RNP AR, and RNP respectively) as well as the Airman's Information Manual and operational rules (parts 91, 121, 135).
(a) AC 20-130A was written prior to implementing performance-based navigation concepts and the evolving RNAV/RNP-based National Airspace System. An FMS incorporating multiple navigation sensor inputs by its very nature has multiple sources of navigation, but the individual sensors have performance limitations on their navigation capabilities. Accordingly, the FMS functions will meet different requirements depending upon the sensors involved and the intended navigation capability. AC 20-138C addresses the performance limitations of the individual sensors contained in the document. These performance limitations must be considered for the overall intended function at the aircraft level during the airworthiness approval (i.e., during the type certificate (TC), amended type certificate (ATC), or supplemental type certificate (STC) approval) to determine any limitations on the aircraft.
(b) In summary, operational rules dictate the navigation equipage requirements.
It is up to the operator to determine how to comply based on their specific operating rules and mission needs.
Chapter 2. T echnical Standard Order Authorization (TSOA) and Airworthiness Approval Considerations - General.
2-1. Guidance for TSOA/Letter of Design Approval (LODA) and Air worthiness Approvals.
Title 14 CFR part 21; subparts D, E, and O provide the regulatory basis defining changes to TC (major/minor changes to aircraft type design), STC, and TSOAs. The regulations and technical standard orders (TSO) can be found at: http://rgl.faa.gov. This chapter provides general guidance on TSOA/LODA and airworthiness approval considerations specific to positioning and navigation equipment.
2-2. TSOA.
a. Several TS Os are available for positioning and navigation-related equipment and components (see appendix 8 of this AC). New TSOs will be written to address modernized GPS and other GNSSs once appropriate equipment standards are in place. It is beneficial to involve the ACO (both engineers and flight test pilots) in equipment evaluations as early as possible for four primary reasons:
(1) Obtaining a TSOA/LODA does not ensure that the equipment will satisfy all of the applicable operational requirements and/or airworthiness regulations when it is installed.
(2) Positioning and navigation equipment has become increasingly more complex and workload intensive with no standardized pilot interface. The human factors evaluation of the equipment is often subjective.
(3) There is no one, single standard for interfacing positioning and navigation equipment to other equipment on-board the aircraft such as displays, autopilots, and terrain warning systems. Positioning and navigation equipment manufacturers should develop compatibility data relative to other equipment for inclusion within the installation manual.
(4) The installed intended function for the equipment needs to be compatible with the original design for the system, including software and hardware design assurance levels.
For example, a decision by the positioning and navigation equipment manufacturer to develop system software to RTCA, Inc. document (RTCA)/(DO)-178B, Software Considerations in Airborne Systems and Equipment Certification, dated December 1, 1992, Level C, may limit installation eligibility if that equipment contributes to failure conditions of other systems that perform critical functions to a higher software design assurance level.
b. It is recommended that the positioning and navigation equipment manufacturer elect to obtain an STC for equipment installation concurrent with obtaining the TSOA/LODA. This has proven to be an effective method to aid installations.
Note: Any applicant may apply for an equipment installation STC. It is not this paragraph’s intent to limit positioning and navigation installation STCs solely to avionics manufacturers.
c. The installation manual and other data approved during the TSOA process can be used as a source of approved data to support an installation airworthiness compliance finding provided the data is applicable to the installation airworthiness requirements (see AC 21-50 (latest revision), Installation of TSOA Articles and LODA Appliances).
2-3. STC-Approved Model List (AML).
a. All STC applican ts are encouraged to use an AML for aircraft makes/models (including 14 CFR parts 23, 25, 27, and 29 aircraft) with similar characteristics and compatible equipment configurations to streamline the approval of subsequent installations. Applicants and ACOs need to contact the applicable directorate for specific policy and guidance information on obtaining an STC-AML.
b. Using the STC-AML method can simplify follow-on installations for makes/models on the AML. The installer needs access to the STC approved data; apply the approved data;
and comply with the detailed installation instructions. The installer then needs only complete FAA Form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, Appliance), identifying the nature of the change to return the aircraft to service (see AC 43.9-1 (latest revision), Instructions for Completion of FAA Form 337).
c. GPS and GPS/SBAS equipment airworthiness approval is not considered novel or unusual per 14 CFR 21.16 and applicants can use designees during the STC process.
2-4. Type Certificate.
Position ing and navigation equipment manufacturers are also encouraged to work with TC holders. This has also proven to be an effective method to aid installations.
Chapter 3. TSO Authorization.
3-1. TSO-C196(AR).
a. TSO-C196a, Airborne Supplemental Navigation Sensors for Global Positioning System Equipment Using Aircraft-Based Augmentation, defines an acceptable standard for GPS equipm ent without ground-based or space-based augmentations. The TSO has been updated to revision ‘a’ for harmonization with TSO-C129a’s cancellation and is intended as the aircraftbased augmentation GPS sensor standard for TSOA/LODA applicants. TSO-C196(AR) equipment has a performance limitation that requires other positioning and navigation systems appropriate to the operation on-board the aircraft.
Note: TSO-C129a has been cancelled, but this does not affect equipment with an existing TSOA/LODA (see paragraph 3-1.c).
b. TSO-C196(AR) defines GPS sensor equipment that incorporates many processing improvements found in the GPS/SBAS equipment minimum operational performance standards (MOPS); but, without the GPS/SBAS requirements. Two improvement examples are: a requirement for the receiver to properly account for satellite range error if it is reflected in the User Range Accuracy index (commonly referred to as being “Selective Availability aware”), and requirements to ensure performance is not degraded due to an increasing radio frequency noise environment as other satellite systems become available.
(1) TSOA/LODA applicants may wish to have a previously approved TSO-C145b/c, Airborne Navigation Sensors Using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS), sensor approved as a TSO-C196a sensor. It is acceptable for these TSO-C196a applicants to take certification credit by re-using data developed during a previous TSO-C145b/c TSOA/LODA approval. RTCA/DO-316, Minimum Operational Performance Standards for Global Positioning System/Aircraft-Based Augmentation System Airborne Equipment, dated April 14, 2009, implemented by TSO- C196(AR) was developed from RTCA/DO-229D, Minimum Operational Performance Standards for Global Positioning System/Wide Area Augmentation System (GPS/WAAS) Airborne Equipment, dated December 3, 2006, implemented by TSO-C145b/c. RTCA/DO- 229D meets or exceeds the performance requirements for TSO-C196(AR). The original RTCA/DO-178B documentation can be re-used if there are no software changes.
(2) Applicants seeking a TSO-C196a TSOA/LODA based on a previously approved TSO-C145b/c sensor must maintain separate part numbers for each unit. It is not acceptable to have both a TSO-C145(AR) and TSO-C196(AR) TSOA/LODA simultaneously on the same article (see paragraph 3-5.b(4)).
Note: Maintaining separate part numbers might only require different software part numbers.
(3) It is acceptable for TSOA/LODA applicants with TSO-C145b/c sensors to simply disable the GPS/SBAS tracking loops in their equipment to qualify as a TSO-C196a 7
sensor.
(4) TSOA/LODA applican ts with TSO-C145a sensors will need to show requirements traceability between RTCA/DO-229C and RTCA/DO-316 along with data applicability to receive appropriate certification credit. In particular, applicants will need to show compliance to all RTCA/DO-316 requirements not addressed in RTCA/DO-229C, and requirements that are more stringent such as enroute/terminal mode accuracy and the broadband external interference noise environment.
c. TSO-C129a was cancelled effective October 21, 2011, but there is no plan to withdraw TSO-C129(AR) authorizations. TSO-C129a cancellation will not affect existing authorizations. Manufacturers can continue production according to their existing TSO-C129(AR) TSOA/LODA. Additionally, the equipment is still eligible for installation according to existing airworthiness approvals and is eligible to receive new airworthiness approvals.
(1) No new TSO-C129a TSOAs/LODAs will be granted after October 21, 2011.
However, we will accept applications for a new TSO-C129a TSOA/LODA until October 21, 2012 if we know that you were working toward a TSO-C129a approval prior to October 21, 2011.
(2) Major changes to the TSO-C129a equipment design will require a new application according to 14 CFR 21.619(b) for TSO-C145c, TSO-C146c or TSO-C196a (or later revisions) except as noted in paragraph 3-1.c(1).
Note: TSO-C129/C129a does not provide sufficient performance for all operational applications.
3-2. TSO-C145(AR)/C146(AR).
a. TSO-C145c, Airborne Navigation Sensors Using the Global P ositioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS) and TSO-C146c, Stand- Alone Airborne Navigation Equipment Using the Global Positioning System (GPS) Augmented by the Satellite Based Augmentation System (SBAS) define an acceptable standard for GPS/SBAS equipment. There is no equipment performance limitation for GPS/SBAS- equipped aircraft to have other positioning and navigation systems on-board.
Note: Refer to the appropriate operating rules and operational guidance documents for equipage requirements.
b. RTCA/DO-229D referenced by the GPS/SBAS TSOs will remain as the MOPS for single-frequency GPS/SBAS equipment. Future multi-frequency/multi-constellation equipment will have a separate MOPS and TSO.
c. There is no plan to withdraw authorizations to the earlier TSO revisions, so manufacturers of TSO-C145a/C146a or TSO-C145b/C146b equipment can continue production according to their TSOA/LODA; and the equipment is still eligible for installation in 8
accordan ce with the guidance in this AC.
d. The difference between revisions ‘b’ and ‘c’ to the GPS/SBAS TSOs is eliminating a 3 decibel (dB) broadband intra-system noise credit for operational Class 1 and Class 2 equipment in RTCA/DO-229D. TSO-C145b/C146b operational Class 3 and Class 4 equipment fully complies with the requirements in TSO-C145c/C146c and is automatically eligible for a revision ‘c’ authorization, i.e., no further evaluation is necessary.
e. TSO-C145b/C146b operational Class 1 and Class 2 equipment that did not claim the 3dB noise credit is also eligible for a revision ‘c’ authorization. The TSOA/LODA holder only needs to provide substantiation that they did not take the noise credit during the original certification.
f. Displays or navigation computers (such as FMSs) may receive a TSO-C146c Class 1, 2, or 3 (functional Class Gamma) incomplete system TSOA/LODA provided they meet the applicable Class Gamma requirements in RTCA/DO-229D and are linked by part number to compatible TSO-C145c sensors in the TSO application documentation. This is an effective method to aid GPS/SBAS installation approvals to make a complete system (sensor, navigation computer, display) at the aircraft level.
Note: See paragraph 3-4 for additional information on FMS incomplete system TSO-C146c Class Gamma TSOA/LODAs and Class Delta-4 FMS implementations.
3-3. TSO-C161a/C162a.
a. TSO-C161a, Ground Based Augmentation Sys tem Positioning and Navigation Equipment, defines an acceptable standard for GPS/GBAS equipment that provides precision approach capability and position/velocity/time (PVT) information to navigation management equipment. TSO-C162a, Ground Based Augmentation System Very High Frequency Data Broadcast Equipment, defines an acceptable standard for GPS/GBAS equipment designed to receive a very high frequency data broadcast (VDB) and output the VDB messages to GPS/GBAS positioning and navigation equipment.
b. TSO-C161a and TSO-C162a invoke only the requirements in RTCA/DO-253C, Minimum Operational Performance Standards for GPS Local Area Augmentation System Airborne Equipment, dated December 16, 2008, that are needed to support Category I (CAT I) precision approach and, if applicable, the GPS/GBAS positioning service. The equipment may output PVT based on either the GPS/GBAS positioning service, or PVT from GPS or GPS/SBAS. The PVT based on GPS/GBAS is only available when the ground station supports the positioning service. TSO-C161a equipment must also obtain a TSO-C145c, TSO-C146c, or TSO-C196a TSOA. Requirements in RTCA/DO-253C needed to support precision approaches beyond CAT I are not invoked in these TSOs as these requirements have not been validated.
Once validated, the FAA will either publish TSO revisions or new TSOs.
c. TSO-C161a and TSO-C162a compliant equipment does not address any RNAV capability. A partial missed approach capability is an option in the GPS/GBAS equipment but is not required (see note). RNAV capability for the initial, intermediate, and missed approach 9
segm ents must be addressed during the aircraft GPS/GBAS integration (see paragraph 14-8.1).
Note: Equipment meeting the RTCA/DO-253C precision and navigation (PAN) requirements can include an optional capability to provide guidance for the initial, straight-out portion of the missed approach segment. However, this capability doesn’t provide guidance for the complete missed approach segment.
3-4. TSO-C115(AR).
a. TSO-C115c, Management System (FMS) Using Multi-Sensor Inputs defines an acceptable certification standard for obtaining design and production approval for multi-sensor navigation systems or FMSs integrating data from multiple navigation sensors. There is no plan to withdraw TSO authorizations granted under TSO-C115b or earlier revisions.
Manufacturers of TSO-C115b, or earlier revision, equipment can continue production according to their TSOA/LODA; and the equipment is still eligible for installation in accordance with the guidance in this AC. However, integrating GNSS into TSO-C115/C115a multi-sensor navigation equipment is considered a major change and requires an application for a TSO-C115c TSOA/LODA.
(1) TSO-C115b only addressed TSO-C129 Class B and C sensors because it was published prior to TSO-C129a, TSO-C145(AR), TSO-C161(AR), and TSO-C196(AR). It is acceptable to integrate any GNSS sensor with TSO-C115b equipment.
Note: The multi-sensor navigation system or FMS must comply with TSO-C115 revision ‘b’ (or a later revision) when integrating GNSS sensors if TSO-C115 is the approval basis. It is not acceptable to use systems certified to earlier TSO-C115 revisions for GNSS sensor integration (see paragraph 3-5.b(1)).
(2) Localizer performance without vertical guidance (LP)/localizer performance with vertical guidance (LPV) is considered a severe major/hazardous failure condition for misleading information (see paragraph 11-2.a). Equipment manufacturers may design FMSs for either a TSO-C146c Class Gamma-3, or Class Delta-4 architecture when integrating LP/LPV capability.
(a) A TSO-C115b (or later revision) FMS designed as a Class Gamma-3 architecture typically has level B software for the LP/LPV processing functions. It is acceptable to have the GPS/SBAS capability and level B software partitioned from other functions in the FMS. See paragraph 3-4.b for additional information on incomplete system TSO-C146c Class Gamma TSOA/LODAs.
(b) TSO-C146c Class Delta-4 provides an ILS look-alike for LP/LPV final approach segment-only capability. A TSO-C115b (or later revision) FMS designed for a Class Delta-4 architecture does not process LP/LPV inputs; does not output LP/LPV deviations, path construction, alerts, etc.; and, does not require the FMS to have a TSO-C146c TSOA/LODA.