AC 20-165B

U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Airworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT Systems Date: 12/07/15 Initiated By: AIR-132 AC No: 20-165B

This advisory circular (AC) provides guidance for the installation and airworthiness approval of Automatic Dependent Surveillance - Broadcast (ADS-B) OUT systems in aircraft.

Susan J. M. Cabler Acting Manager, Design, Manufacturing, & Airworthiness Division Aircraft Certification Service

CONTENTS Paragraph Page ii

Chapter 1. General Information1

1.1 Purpose1

1.2 Audience1

1.3 Cancellation1

1.4 Where to Find This AC1

1.5 Scope2

1.6 Background2

2.1 ADS-B OUT System Approval Process4

2.2 Aircraft Flight Manual4

2.3 Continuing Airworthiness Requirements5

Chapter 3. ADS-B OUT System Installation Guidance8

3.1 General Installation Guidance8

3.2 ADS-B Equipment12

3.3 Position Source17

3.4 Barometric Altitude Source21

3.5 Heading Source23

3.6 TCAS Source23

3.7 Pilot Interface24

3.8 ADS-B Antenna Interface28

3.9 Vertical Rate Source31

3.10 Air-Ground Considerations33

3.11 Foreign Airspace Requirements34

Chapter 4. Test and Evaluation35

CONTENTS (CONTINUED) Paragraph Page iii

4.1 Ground Test35

4.2 Flight Test41

4.3 Flight Test With FAA Ground System41

4.4 International Flight Test Options47

4.5 Subsequent Flight Test Data Reuse47

Appendix A. Message Element DescriptionsA-1

A.1 PurposeA-1

A.2 Message ElementsA-1

Appendix B. Identifying and Qualifying ADS-B Position SourcesB-1

B.1 PurposeB-1

B.2 OrganizationB-1

B.3 General Guidance for All Position SourcesB-1

B.4 GNSS Position SourcesB-4

B.5 Tightly-Coupled GNSS/IRS Position SourcesB-28

B.6 Non-GNSS Position SourcesB-30

B.7 Future Position SourcesB-31

Appendix C. Latency AnalysisC-1

C.1 PurposeC-1

C.2 AnalysisC-1

C.3 Equipment Latency BudgetC-2

C.4 General Latency IssuesC-3

C.5 Latency Analysis ExampleC-5

Appendix D. Definitions and AcronymsD-1

CONTENTS (CONTINUED) Paragraph Page iv

D.1 DefinitionsD-1

D.2 AcronymsD-7

Appendix E. Related DocumentsE-1

E.1 FAA DocumentsE-1

E.2 RTCA, Inc. DocumentsE-3

E.3 ARINC DocumentsE-3

E.4 SAE International DocumentsE-3

E.5 European Aviation Safety Agency (EASA) DocumentsE-4

CONTENTS (CONTINUED) v

FIGURES Number Page

Figure 1. Functional Overview of ADS-B OUT System3

Figure 2. Example of Aircraft Length and Width Code Determination14

Figure 3. Position Offset31

TABLES Number Page

Table 1. Emitter Category16

Table 2. Accuracy and Integrity Requirements35

Table 3. Minimum and Maximum Transmitted Power From TSO-C166b40

Table 4. Minimum and Maximum Transmitted Power From TSO-C154c40

Table 5. Turns44

Table 6. Climb Speeds45

Table 7. Descent Speeds45

Table 8. Accuracy and Integrity Requirements During Flight46

Table A-1. NACP ValuesA-4

Table A-2. NACVA-5

Table A-3. NIC ValuesA-6

Table A-4. SIL Values, Probability of Exceeding the NIC Containment RadiusA-7

Table A-5. Source Integrity Level SupplementA-7

Table A-6. System Design AssuranceA-8

Table B-1. Modified IFOR Threshold Constellation State ProbabilitiesB-6

Table B-2. Estimated GNSS Availabilities (Minimum Threshold Constellation)B-7

Table C-1. Latency Analysis ExampleC-5

Table D-1. NACP EncodingD-3

Table D-2. NACVD-4

Table D-3. NIC EncodingD-4

Table D-4. SIL EncodingD-5

Table D-5. SDA EncodingD-6

1 CHAPTER 1. GENERAL INFORMATION

1.1 Purpose.

This AC provides guidance for the initial installation and airworthiness approval of Automatic Dependent Surveillance - Broadcast (ADS-B) OUT equipment in aircraft.

1.1.1 Acceptable Means of Compliance.

This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to install ADS-B OUT equipment. However, if you use the means described in this AC, you must follow it entirely. The latest version of a document should be used where “()” follows its number.

1.1.2 Intent of This AC.

This AC is primarily intended for installations compliant with the aircraft requirements of Title 14 of the Code of Federal Regulations 14 CFR 91.225 and § 91.227.

Airworthiness compliance will be evaluated based on the applicable intended function rule (such as §§ 23.1301, 25.1301, 27.1301, or 29.1301) recognizing that the intended function is to meet the equipment requirements in §§ 91.225 and 91.227. It is possible to receive airworthiness approval for your ADS-B OUT system with a different intended function; however, we strongly discourage this type of installation unless it is in accordance with the criteria for ADS-B OUT in foreign non-radar airspace (for example, Approved Means of Compliance (AMC) 20-24, Certification Considerations for the Enhanced ATS in Non-Radar Areas using ADS-B Surveillance (ADS-B-NRA) Application via 1090 MHZ Extended Squitter). Applicants using this AC to install ADS-B systems that are not compliant with §§ 91.225 and 91.227 must follow all aspects of this AC or propose alternate means, as appropriate, to the Federal Aviation Administration (FAA).

1.2 Audience.

This AC is for anyone who is applying for an initial type certificate (TC), supplemental type certificate (STC), amended TC, or amended STC for the installation and continued airworthiness of ADS-B OUT equipment.

1.3 Cancellation.

This AC supersedes AC 20-165A, Airworthiness Approval of Automatic Dependent Surveillance - Broadcast (ADS-B) Out Systems. Equipment previously approved pursuant to the guidance in the superseded ACs is still valid for the operations and conditions stated in their approvals.

1.4 Where to Find This AC

1.4.1 You may find this AC at http://www.faa.gov/regulations_policies/advisory_circulars/.

1.4.2 If you have any suggestions for improvements or changes, you may use the template provided at the end of this AC.

1.5 Scope.

1.5.1 This AC only addresses the installation of ADS-B OUT systems. Installation guidance for ADS-B IN can be found in the latest version of AC 20-172, Airworthiness Approval for ADS-B In Systems and Applications. Installation guidance for Flight Information Services - Broadcast (FIS-B) can be found in the latest version of AC 20-149, Installation Guidance for Domestic Flight Information Services - Broadcast. If Technical Standard Order (TSO)-C166b, Extended Squitter Automatic Dependent Surveillance - Broadcast (ADS-B) and Traffic Information Service - Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz), or TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance Broadcast (ADS-B) Equipment Operating on Frequency of 978 MHz, equipment being installed has a receive capability, but that receive capability is not integrated into the aircraft to support ADS-B IN display applications, you do not need to demonstrate specific ADS-B receive performance during the ADS-B OUT installation approval.

4.5.6Appendix A to this AC provides a description of the message elements contained in ADS-B messages. Guidelines for qualifying position sources can be found in

4.5.6Appendix B. Guidelines for accomplishing latency analysis can be found in

4.5.6Appendix C. 4.5.6Appendix D provides a list of definitions and acronyms that are used in this AC. The latest version of a document should be used where “()” follows its number. 4.5.6Appendix E provides a list of related documents.

1.6 Background.

ADS-B is a next generation surveillance technology incorporating both air and ground aspects that provide air traffic control (ATC) with a more accurate picture of the aircraft’s three-dimensional position in the en route, terminal, approach, and surface environments. The aircraft provides the airborne portion in the form of a broadcast of its identification, position, altitude, velocity, and other information. The ground portion is comprised of ADS-B ground stations, which receive these broadcasts and direct them to ATC automation systems for presentation on a controller’s display. In addition, aircraft equipped with ADS-B IN capability can receive these broadcasts and display the information to improve the pilot’s situation awareness of other traffic.

1.6.1 ADS-B Description.

ADS-B is automatic because no external interrogation is required. It is dependent because it relies on onboard position sources and broadcast transmission systems to provide surveillance information to ATC and other users. Figure 1 below provides a functional overview of an aircraft ADS-B system.

1.6.2 Functional Overview Figure 1. Functional Overview of ADS-B OUT System ADS-B Antenna ADS-B Antenna ADS-B Equipment Position/ VelocityHeading Air/Ground Status Pilot Input TCAS Status Baro Altitude

1.6.3 ADS-B OUT, ADS-B IN, TIS-B and ADS-R.

ADS-B OUT refers to an aircraft broadcasting own-ship information. ADS-B IN refers to an aircraft’s ability to receive ADS-B information, such as ADS-B messages from other aircraft or Traffic Information Services-Broadcast (TIS-B), and Automatic Dependent Surveillance - Rebroadcast (ADS R) from the ground infrastructure.

1.6.4 ADS-B links.

There are two ADS-B link options: 1090 extended squitter (1090ES) and universal access transceiver (UAT). The 1090ES equipment operates on 1090 MHz and has performance requirements specified in TSO-C166b. The UAT operates on 978 MHz and has performance requirements specified in TSO-C154c. This AC addresses installing equipment meeting the requirements of either TSO.

Note: § 91.225 requires 1090ES in Class A airspace.

4 CHAPTER 2. THE APPROVAL PROCESS AND NECESSARY DOCUMENTATION

2.1 ADS-B OUT System Approval Process.

This AC addresses the initial airworthiness approval through the type certification or supplemental type certification process of an ADS-B OUT system that meets the performance requirements of the applicable TSO and the requirements of § 91.227.

Information on the STC and TC processes can be found in the latest revisions of AC 21-40, Guide for Obtaining a Supplemental Type Certificate, and FAA Order 8110.4, Type Certification. Parties interested in approving ADS-B IN systems should refer to AC 20-172(),Airworthiness Approval for ADS-B In Systems and Applications

2.1.1 Installation of ADS-B OUT Equipment.

This AC covers installation of the ADS-B OUT equipment, updates to the flight manual, updates to the instructions for continued airworthiness (ICA), guidance for interfacing systems, ground test, and flight test.

2.1.2 The ADS-B OUT System.

The ADS-B OUT system is depicted in figure 1 above and includes the ADS-B equipment, a position source, a barometric altitude source, an air-ground status source, a Traffic Alert and Collision Avoidance System (TCAS) II source if the aircraft is equipped with TCAS II, an optional heading source, and all associated antennas and displays. Applicants should list the components that make up the ADS-B system in their master drawing list. You may demonstrate interoperability with multiple components for a given function. For example, you may request approval for a secondary position source, or add multiple unique position sources to the STC.

2.2 Aircraft Flight Manual.

Include ADS-B OUT operating limitations, normal operating procedures, and a system description in the Airplane Flight Manual (AFM), Rotorcraft Flight Manual (RFM), AFM Supplement (AFMS), or RFM Supplement (RFMS). The flight manual must also state that the installation meets the requirements of § 91.227. This can be accomplished by adding the following statement to the General or Normal Procedures section of the flight manual:

The installed ADS-B OUT system has been shown to meet the equipment requirements of 14 CFR 91.227.

2.2.1 Operating Limitations.

The flight manual should describe any operating limitations necessary for safe operation because of design, installation, or operating characteristics.

2.2.2 Operating Procedures.

Describe normal and non-normal operating procedures for the system in the flight manual.

2.2.2.1 Describe any actions expected of the pilot.

2.2.2.2 Describe how to enter the Mode 3/A code, Flight ID, operate the IDENT function, and activate or deactivate emergency status. If the ADS-B system and transponder do not have a single point of entry for the Mode 3/A code, IDENT, and emergency status, the flight manual procedures must ensure conflicting information is not transmitted from the ADS-B system and transponder.

2.2.2.3 Describe any ADS-B OUT displays and provide instructions to the pilot on how to respond to any error conditions.

2.2.2.4 Describe how the ADS-B OUT system can be disabled, if there is an ability to disable the ADS-B OUT system. Also, describe the means through which the pilot can detect that the system has been disabled. The flight manual must address the effects of turning off the ADS-B OUT system, including the effects on the transponder and TCAS II if disabling the ADS-B OUT system also disables the transponder or the TCAS II.

2.2.2.5 Include guidance in the flight manual on when to enable the ADS-B OUT system. The ADS-B OUT system must be enabled (turned ON) during all phases of flight operation including airport surface movement operations.

ADS-B IN surface applications and ATC surface surveillance will use ADS-B OUT broadcasts; thus, it is important for aircraft ADS-B OUT systems to continue to transmit on the airport surface. If the ADS-B OUT function is embedded in a Mode S transponder, the flight manual, checklists, and any operator procedures manuals must be updated accordingly with ADS-B OUT operations guidance.

Note: Historically, transponders have been turned on by the flightcrew when entering the runway for takeoff and turned off or to standby when exiting the runway after landing. When ADS-B is integrated into a Mode S transponder, the existing guidance for transponder operation must be updated to ensure the ADS-B system is operating during airport surface movement operations.

2.2.3 System Description.

Describe the ADS-B OUT system and the interface with other systems on the aircraft in the flight manual. If multiple position sources are interfaced to the ADS-B transmitter, describe the source selection mechanism and any related indications.

2.3 Continuing Airworthiness Requirements.

2.3.1 ADS-B OUT Equipment.

Follow the ADS-B equipment manufacturer’s guidance for periodic inspection and maintenance of the ADS-B system. ICA must be provided and must address any maintenance requirements to maintain the ADS-B equipment.

2.3.2 ADS-B Functionality in a Transponder.

Transponders that incorporate ADS-B functionality (such as with 1090ES) must continue to meet the operational requirements of 14 CFR 91.215, §91.217, and §91.413 and comply with the transponder system tests and inspections called out in 14 CFR part 43, appendix F. Refer to AC 43-6, Altitude Reporting Equipment and Transponder System Maintenance and Inspection Practices.

2.3.3 Altimetry Systems and Altitude Reporting Equipment.

Altitude reporting equipment connected to the ADS-B system must comply with all applicable 14 CFR 91.217, §91.411, and part 43, appendix E test and inspection requirements. Refer to AC 43-6. If the altimetry system is compliant with the Reduced Vertical Separation Minimum (RVSM) standards, the requirements and tolerances stated in the approved RVSM maintenance program must be met. ADS-B installation does not alter these requirements.

2.3.4 Maintenance and Design Changes to Interfacing Components.

The ADS-B system interfaces with multiple external components, such as position sources and altimetry sources. The installer should list all interfacing components in the ICA. It is important that any future maintenance or design changes to these interfacing components be accomplished in such a way that continued satisfactory performance of the overall ADS-B system is maintained.

2.3.4.1 Maintenance of the ADS-B System.

The ADS-B system installation must include ICA that meet the typical requirements for a system installation, which includes how to accomplish a complete functional check of the system.

2.3.4.2 ADS-B Source System Components.

Although the installer may not have access to the specific source system ICA to incorporate changes into those specific documents, the installer must do an analysis of the source systems to determine what maintenance actions on those source systems would require a functional test of the ADS-B system to verify that the system is operating properly. In particular, those systems providing a dedicated input to the ADS-B system that cannot be verified by other means should be tested as part of the ADS-B system as a whole. Once the installer identifies those actions, they must provide recommended language for the operator to include in their ICA. If the installer determines that removal and replacement of the Global Positioning System (GPS) receiver requires a full functional check of the ADS-B system because the GPS input to the ADS-B cannot be verified by other means, its instructions to the operator should indicate this. For example:

Modify the R&R ICA instructions in your GPS maintenance manual to include the following statement:

“Removal and replacement of the GPS receiver also

7 requires a full functional check of the ADS-B system per MM XX-XX-XX, Pg xxx. Make a logbook entry for accomplishment of this test”..

2.3.4.3 Design Changes to Interfacing Components.

Ensuring continued airworthiness of the ADS-B system following upgrades of interfacing components could be problematic if the installer of the ADS-B system is unaware of design changes to interfacing components, or if the installer of the updated interfacing component is unaware of a potential impact to the ADS-B system. To avoid this problem, the ADS-B system installer must update the ICA for each interfacing system with a process that ensures continued airworthiness of the ADS-B system following design changes to the interfacing component.