AC 20-140C

U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Guidelines for Design Approval of Aircraft Data Link Communication Systems Supporting Air Traffic Services (ATS) Date: 9/28/16 Initiated By: AIR-130 AC No: 20-140C This advisory circular (AC) provides guidance on compliance with the airworthiness standards for aircraft that incorporate a data communication system supporting ATS communications.

This guidance is applicable to requests for a new, amended, or supplemental type certificate for Title 14 of the Code of Federal Regulations (14 CFR) part 23, 25, 27 and 29 aircraft.

If you have suggestions for improving this AC, you may use the Advisory Circular Feedback form at the end of this AC.

R ichard E. Jennings Acting Manager, Design, Manufacturing, & Airworthiness Division Aircraft Certification Service

Contents Paragraph Page ii

1 What is the Purpose of this Advisory Circular (AC)?1

2 Who Does this AC Affect?1

3 Does this AC Cancel any Prior AC?1

4 What are the Important Changes to this AC?2

5 Definitions for Different Types of Data Link Systems2

5.1 Overview2

5.2 Data link Systems – Interoperability Designators3

5.3 Data link Services – Safety and Performance Criteria7

6 Means of Compliance for the Aircraft Data Link System9

6.1 Interoperability Criteria9

6.2 Safety and Performance Criteria15

7 Design Considerations for Aircraft Data Link Systems16

7.1 System Design16

7.2 Flight Deck Annunciation17

7.3 Flight Deck Controls18

7.4 Message Presentation19

7.5 Flight Deck Printer20

7.6 Data Communication Recording20

8 Ground and Flight Test Evaluation20

9 Airplane/Rotorcraft Flight Manual (A/RFM)20

9.1 Operating Limitations21

9.2 Operating Procedures21

Appendix A Related DocumentsA-1

Appendix B List of AcronymsB-1

iii Figures Number Page

Figure 1. Different ATSU/Aircraft Data Link Application Interoperability Designators4

Figure 2. Flight Manual Supplement Example22

Tables Number Page

Table 1. Sub-network Designators7

Table 2. Communication performance specifications (apply to CPDLC)8

Table 3. Surveillance performance specification (apply to ADS-C)8

Table 4. Interoperability Criteria for the Aircraft Data Link System10

1 1 WHAT IS THE PURPOSE OF THIS ADVISORY CIRCULAR (AC)?

1.1 This AC provides guidance material for applicants seeking an airworthiness approval for aircraft with an installed data link system intended to support air traffic services (ATS) data communication. It identifies specific configurations of aircraft data link systems for applicants seeking approval for type certificates (TC) and supplemental type certificates (STC) in order to facilitate operational approvals. Appendix A of this AC provides a list of related documents. Appendix B of this AC contains a list of applicable acronyms.

1.2 This AC describes an acceptable means, but not the only means, for you to gain airworthiness approval for aircraft data link system equipment. However, if you use the means described in this AC, you must follow it in all important respects.

1.3 The term “must” is used in this AC to indicate a mandatory requirement driven by regulation that is to be followed when using the guidance in this AC. The term “should” is used in this AC to indicate a recommendation and not a requirement when using the guidance in this AC. Since this AC represents an accepted means of compliance, an applicant seeking an alternative to any requirement or recommendation within this AC will need to be discussed with the Aircraft Certification Office (ACO) in order to achieve a common performance level with the AC.

2 WHO DOES THIS AC AFFECT?

This AC provides guidelines for applicants seeking design approval of aircraft data link systems used for communication supporting ATS. ATS data communications included in this AC are Controller Pilot Data link Communications (CPDLC), Automatic Dependent Surveillance-Contract (ADS-C) and some Aircraft Communications Addressing and Reporting System (ACARS) (i.e., Departure Clearance [DCL], Oceanic Clearance [OCL] and Terminal Weather Information for Pilots [TWIP]) messages. ATS communication includes Flight Information Service (FIS) messages. This AC addresses only Data Link- Automatic Terminal Information Service (D-ATIS) for Flight Information Service (FIS) communications. Flight Information Service – Broadcast (FIS-B) installation guidelines are available in AC 20-149B, Installation Guidance for Domestic Flight Information Service - Broadcast (or latest revision).

3 DOES THIS AC CANCEL ANY PRIOR AC?

This AC supersedes and cancels AC 20-140B, dated September 27, 2012.

2 4 WHAT ARE THE IMPORTANT CHANGES TO THIS AC?

4.1 This AC adds airworthiness approval guidance for a Baseline 2 (B2) data communications system. Operators will need to equip their aircraft with B2, as defined in this AC, to conduct future NextGen operations in the U.S. National Airspace System (NAS) including Interval Management (IM) and Dynamic Required Navigation Performance (DRNP).

4.2 This AC recognizes Inmarsat-Swift Broadband (SBB) satellite communications as a viable sub-network for certain ATS data communication systems.

4.3 This AC provides references to current FAA cybersecurity policy and guidance to help you evaluate the need to incorporate cybersecurity provisions into your data communication installation.

4.4 This AC updates cross-referenced policy and guidance to the latest applicable revisions.

5 DEFINITIONS FOR DIFFERENT TYPES OF DATA LINK SYSTEMS.

5.1 Overview.

5.1.1 This AC defines interoperability designators for data link capability in terms of the data link applications. It identifies all Interop, Sub-network, and Performance designators with “bold red text”. Associated with the data link capability, this AC defines interoperability, safety, and performance criteria for the aircraft data link system. For domestic, oceanic and remote airspace, when data link is required for operations, this AC defines designators to identify the criteria for the design approval. This AC covers only the aircraft allocations of these criteria and the aircraft’s ability to interoperate and perform with a representative ground system. The FAA will also consider the communication service provider (CSP), air navigation service provider (ANSP) and operator when evaluating requests for operational authorization according to AC 120-70C, Operational Authorization Process for use of Data Link Communication System (or latest revision). ANSPs typically refer to the type of data link system through the use of these designators to prescribe data link capability and performance in specified airspace.

5.1.2 International Civil Aviation Organization’s (ICAO’s) Global Operational Data Link (GOLD) Manual, Doc 10037 and Performance-Based Communication and Surveillance (PBCS) Manual, Doc 9869 facilitate global harmonization of existing data link operations and resolve regional and/or State differences impacting seamless operations.

PBCS includes required communication performance (RCP) specifications, required surveillance performance (RSP) specifications, and guidelines on post-implementation monitoring and corrective action. The RCP/RSP specifications are based on RTCA DO-350A/EUROCAE ED-228A, Safety and Performance Standard for Baseline 2 ATS

3 Data Communications (Baseline 2 SPR Standard). The guidance in this AC is compatible with GOLD and PBCS.

5.1.2.1 GOLD Doc 10037 edition 1 and PBCS Doc 9869 edition 2 include provisions for existing operations (i.e., operational capabilities supported by Future Air Navigation System FANS 1/A+ and Aeronautical Telecommunication Network – Baseline 1 ATN B1).

5.1.2.2 Future amendments to these manuals are planned to include operational capabilities supported by B2.

5.2 Data link Systems – Interoperability Designators.

5.2.1 “Data link” is a generic term that encompasses different types of data link systems and sub-networks.

5.2.2 Figure 1 shows different air traffic service unit (ATSU) ground systems and aircraft systems that are interoperable. Each type of ATSU and aircraft data link system has a designator to indicate acceptable interoperable configurations for the data link applications. Future air navigation system (FANS 1/A) designators are shown for operational purposes and are not appropriate for new installation approvals (new FANS 1/A+ installations are acceptable).

Note 1: Figure 1 is comprised of a graphical portion and a table with text providing more detail information. Notes in the table of Figure 1 elaborates when an aircraft and ATSU is able to perform data communications when accommodation interoperability requirements are included in the aircraft/ATSU implementation.

Note 2: Figure 1 does not indicate when data communications may occur when an aircraft and/or ATSU is configured with multiple capability (i.e., multiple stack implementation).

Note 3: Table 4 identifies interoperability requirements of the different data communication systems that the FAA considers acceptable for an applicant seeking a new, amended, or supplemental type certification for an aircraft that supports ATS communication.

4 Figure 1. Different ATSU/Aircraft Data Link Application Interoperability Designators Interop Designator Description

ACARS ATS

ATSU CADS FANS 1/A ATS applications, departure clearance (DCL), oceanic clearance (OCL), terminal weather information for pilots (TWIP) and data link – automatic terminal information service (D-ATIS) supported by aircraft communications addressing and reporting system (ACARS).

Communication service provider’s (CSP) centralized ADS-C system (CADS) enables an ATSU without FANS 1/A capability to receive ADS-C reports from any FANS 1/A, FANS 1/A+ or FANS 1/A ADS-C aircraft.

Initial FANS 1/A supported with ATS applications, ATS facilities notifications (AFN), Controller Pilot Data link Communications (CPDLC) and automatic dependent surveillance –Contract (ADS C) supported by FANS 1/A. This AC does not provide an acceptable means of compliance for type design approval for FANS 1/A designated aircraft, but you may use FANS 1/A+ for new design approvals (see below).

Note: FANS 1/A typically involves communication (CPDLC), navigation (area navigation/required navigation performance, RNAV/RNP) and surveillance (ADS-C). This document refers to the FANS 1/A for the data link system, which includes the CPDLC and ADS C applications. Refer to ICAO Doc 9613 for guidance material on navigation (RNAV/RNP) qualification and use.

ATN B1 FANS 1/A FANS 1/A+ FANS 1/A (Generic) Aircraft with multiple types of data link systems ATSU in Continental airspace ATSU in Oceanic and remote airspace CSP CADS

ATSU CADS ATSU in Any airspace

ACARS ATS

ACARS ATS ATN B1 FANS 1/A B2 B2* *As defined in this AC.

Can interoperate with any B2 ground station.

5 Figure 1. Different ATSU/Aircraft Data Link Application Interoperability Designators (continued) Interop Designator Description FANS 1/A+ Same as FANS 1/A, except with additional features, such as the message latency timer function, described in DO-258A/ED-100A, paragraph 4.6.6.9.

Note 1: FANS 1/A+ aircraft are interoperable with FANS 1/A and FANS 1/A+ ground stations. However, message latency capability is only available when FANS 1/A+ ground stations interoperates with FANS 1/A+ aircraft.

Note 2: Seamless transition of ATS data link service occurs between ATN B1 and FANS 1/A+ ground stations when:

 Aircraft equipped with ATN B1 and FANS 1/A+ data link system also incorporates interoperability requirement IR-207, IR-209, IR-210, IR-211, IR-212, IR-214 and IR-215 of DO-305A/ED-154A.

 ATN B1 ground station incorporates interoperability requirement IRec-1 and IR-213 of DO-305A/ED-154A.

 FANS 1/A+ ground station incorporates interoperability requirement IR-208 of DO-305A/ED-154A.

Otherwise, the flight crew will lose their data link service requiring the flight crew to manually perform a logon to reestablish ATS data link service.

Note 3: Seamless transition of ATS data link service occurs between B2 and FANS 1/A+ ground stations when:

 Aircraft equipped with B2 and FANS 1/A+ data link system also incorporates interoperability requirement NIR-153, NIR-155, NIR-156, NIR-157, NIR-158, NIR-160 and NIR-161 of DO-352A/ED-230A.

 B2 ground station incorporates interoperability requirement NIRec-3 and NIR-159 of DO-352A/ED-230A.

 FANS 1/A+ ground station incorporates interoperability requirement NIR-154 of DO-352A/ED-230A.

Otherwise, the flight crew will lose their data link service requiring the flight crew to manually perform a logon to reestablish ATS data link service.

Note 4: To allow a FANS 1/A+ data communication system on an aircraft to communicate with a ATN B1 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A+ aircraft by incorporating the interoperability requirements of DO-305A/ED-154A.

Note 5: To allow a FANS 1/A+ data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A+ aircraft by incorporating the interoperability requirements of DO-352A/ED-230A.

ATN B1 ATS applications CM and CPDLC supported by Aeronautical Telecommunication Network – Baseline 1 (ATN B1): a) Context management (CM) is a data link application providing data link initiation capability (DLIC);

b) CPDLC (Version 1) for ATC communications management (ACM), ATC clearance (ACL), and ATC microphone check (AMC) Note 1: Interoperability for departure clearance (DCL), downstream clearance (DSC), data link – automatic terminal information service (D-ATIS), and flight plan consistency (FLIPCY) data link services, which are defined in DO-280B/ED-110B are not supported.

Note 2: Seamless transition of ATS data link service between ATN B1 and FANS 1/A+ ground stations when:

 Aircraft equipped with ATN B1 and FANS 1/A+ data link system also incorporates interoperability requirement IR-207, IR-209, IR-210, IR-211, IR-212, IR-214 and IR-215 of DO-305A/ED-154A.

 ATN B1 ground station incorporates interoperability requirement IRec-1 and IR-213 of DO-305A/ED-154A.

 FANS 1/A+ ground station incorporates interoperability requirement IR-208 of DO-305A/ED-154A.

Otherwise, the flight crew will lose their service requiring the flight crew to manually perform a logon to reestablish ATS data link service.

Note 3: To allow a FANS 1/A+ data communication system on an aircraft to communicate with a ATN B1 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A+ aircraft by incorporating the interoperability requirements of DO-305A/ED-154A.

Note 4: To allow an ATN B1 data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the ATN B1 aircraft by incorporating the interoperability requirements of DO-353A/ED-231A.

Note 5: To allow a B2 data communication system on an aircraft to communicate with an ATN B1 data communication system at an ATSU, the B2 data communication system on the aircraft needs to accommodate the ATN B1 ground system by incorporating the interoperability requirements of DO-353A/ED-231A.

6 Figure 1. Different ATSU/Aircraft Data Link Application Interoperability Designators (continued) Interop Designator B2 Description Version of the Baseline 2 Data Communication system described in this section. The United States plans to use B2, as defined in this AC, as part of FAA’s NextGen initiative. An aircraft equipped with B2, as defined in this AC, is fully interoperable with any B2 ground station. Aircraft equipped with a version of B2 other than that defined by this AC are not eligible for the B2 interop designator. B2 is comprised of the following data link applications and data link services.

a) Context management (CM) is a data link application supporting the following data link service: Data link initiation capability (DLIC).

b) CPDLC (Version 3) is a data link application supporting the following data link services: ATC Communications Management (ACM), Clearance Request and Delivery (CRD), ATC Microphone Check (AMC), Departure Clearance (DCL), Data Link Taxi (D-TAXI), Oceanic Clearance Delivery (OCL), 4-Dimensional Trajectory Data Link (4DTRAD), Information Exchange and Reporting (IER), In-Trail Procedure (ITP), Interval Management (IM), and Dynamic Required Navigation Performance (DRNP).

c) ADS-C (Version 2) is a data link application supporting the following data link services: 4-Dimensional Trajectory Data Link (4DTRAD), Information Exchange and Reporting (IER), Position Reporting (PR), Interval Management (IM) and Dynamic Required Navigation Performance (DRNP).

Note 1: To allow a FANS 1/A+ data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A+ aircraft by incorporating the interoperability requirements of DO-352A/ED-230A.

Note 2: To allow an ATN B1 data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the ATN B1 aircraft by incorporating the interoperability requirements of DO-353A/ED-231A.

Note 3: To allow a B2 data communication system on an aircraft to communicate with an ATN B1 data communication system at an ATSU, the B2 data communication system on the aircraft needs to accommodate the ATN B1 ground system by incorporating the interoperability requirements of DO-353A/ED-231A.

5.2.3 Table 1 below provides the designators for each type of sub-network:

Table 1. Sub-network Designators Sub-network Designator Description of designator VDL M0/A Very high frequency data link – mode 0/A VDL M2 Very high frequency data link – mode 2 HFDL High frequency data link SATCOM (Classic Aero) Inmarsat or MT-SAT – Classic Aero satellite communications SATCOM (SBB) Inmarsat – Swift Broadband satellite communications SATCOM (SBD) Iridium – short burst data satellite communications

5.2.4 The applicable interoperability standards for each type of data link system and each type of sub-network allocate criteria to the operator, the aircraft data link system, and the air traffic service provider to ensure that the aircraft system, the ground system, and sub-networks are compatible.

5.3 Data link Services – Safety and Performance Criteria.

RTCA DO-350A/EUROCAE ED-228A (Any Airspace SPR), provides operational, safety and performance criteria for data link services that are applicable in continental, oceanic and remote airspace for normal ATC communication and surveillance for a variety of operational capabilities. DO-350A/ED-228A defines communication and surveillance performance designators as shown in Table 2 and Table 3, which include the applicable safety criteria. The RCP/RSP specifications shown in Table 2 and Table 3 may be prescribed by an ANSP when required for air traffic services (ATS) provision in a particular airspace or applied for operational approval and aircraft system design approval. Section 5 of this AC only provides an overview of the PBCS framework, whereas, the applicable criteria for aircraft system design approval is specified in Section 6 of this AC.

8 Table 2. Communication performance specifications (apply to CPDLC) RCP Specification Transaction time (sec) Continuity Availability Integrity RCP 130 130 0.999 0.989 Malfunction = 10-5 per flight hour RCP 240 240 0.999 0.989 Malfunction = 10-5 per flight hour RCP 400 400 0.999 0.989 Malfunction = 10-5 per flight hour Table 3. Surveillance performance specification (apply to ADS-C) RSP Specification Surveillance overdue delivery time (sec) Continuity Availability Integrity RSP 160 160 0.999 0.989 Navigation FOM See Note below Time at position accuracy +/- 1 sec (UTC) Data Integrity Malfunction = 10-5 per flight hour RSP 180 180 0.999 0.989 Navigation FOM See Note below Time at position accuracy +/- 1 sec (UTC) Data Integrity Malfunction = 10-5 per flight hour RSP 400 400 0.999 0.989 Navigation FOM See Note below Time at position accuracy +/- 1 sec (UTC) Data Integrity Malfunction = 10-5 per flight hour Note: The navigation figure of merit (FOM) is specified based on the navigation criteria associated with this spec. For example, if RNP 4 is prescribed, then for ADS-C surveillance service, the FOM level would need to be 4 or better. In all cases, when the navigation capability no longer meets the criteria specified for the operation, the flight crew is responsible for reporting the non-compliance to ATC in accordance with ICAO procedures.

9 6 MEANS OF COMPLIANCE FOR THE AIRCRAFT DATA LINK SYSTEM.

This section includes the interoperability, safety and performance criteria for the aircraft data link system. Alternate means of compliance must substantiate interoperability.

You must identify any operational limitations and/or restrictions. This includes, but is not limited to partial compliance to the criteria provided for any of the designators selected in Table 4 as applicable.

6.1 Interoperability Criteria.

6.1.1 Table 4 provides interoperability criteria for aircraft that incorporate ATN B1, B2, FANS 1/A+, or ACARS ATS interop designator(s), or any combination of those interop designators. An aircraft data link system may support any combination of the interop designators in Table 4 as applicable.

Note 1: Aircraft incorporating Baseline 2 data communication capability, as defined in this AC, will receive a B2 interop designator (meeting criteria of Table 4). The B2 interop designator indicates that the installed data communications system supports future NextGen operations planned for use in the US NAS, including IM and DRNP.

Note 2: Since only the version of B2 defined in this AC will fully support future NextGen operations in the US NAS (particularly IM and DRNP), aircraft must be equipped with the version of Baseline 2 defined in this AC to be eligible for operational approval to use the B2 interop designator for operations in the US NAS.

6.1.2 The interoperability criteria in each row of Table 4 are applicable in their entirety to the aircraft data link system for the row (capabilities and the sub-networks selected). To meet 14 CFR 23/27/29.1301(a) or 25.1301(a)(1), as applicable, aircraft data link system installations must comply with all the referenced criteria in a row in order to receive the associated interoperability designator. The interoperability criteria define the CPDLC message sets for each data link system (e.g., ATN B1, FANS 1/A+, or B2). Therefore, aircraft with multiple data link systems installed must incorporate CPDLC message sets for each supported data link system.

Note 1: "CPDLC" is a data link application that includes a CPDLC message set, which comprises message elements that are used to construct messages to support the operational intent of the message elements defined in the “Message element intended use” column of the tables contained in Appendix 5 of ICAO Document 4444, Procedures for Air Navigation Services/Air Traffic Management (PANS ATM).

Note 2: Appendix A of ICAO GOLD Document 10037, Global Operational Data Link (GOLD) Manual, First Edition, identifies the CPDLC message elements defined in PANS ATM (see Note 2) and associates those message elements amongst the message elements defined