AC 120-70A

Advisory Circular

Subject: Operational Authorization Process for use of Data Link Communication System Date: 12/29/05 Initiated by: AFS-430 AC No: 120-70A

This advisory circular (AC) presents various methods for operators of differing data link systems to meet international standards set by the International Civil Aviation Organization (ICAO) and the Regional Airspace Authorities. The FAA notes that there is presently no requirement in Title 14 of the Code of Federal Regulations to have data link communications when operating in the National Airspace System (NAS). Instead, the regulations in Title 14 govern radio communication systems, and nothing in this AC absolves an operator from the requirement to have and use a voice communication system when operating in the NAS. However, operators that choose to use a data link system (in addition to the required voice communication system) must obtain FAA design approval and a revision to their Operating Specifications. Thus, the FAA is issuing this AC is to present the consensus of the aviation community regarding acceptable methods, procedures, and training for users of data link systems.

ORIGINAL SIGNED BY Carol Giles for

James J. Ballough Director, Flight Standards Service

CONTENTS

Page

1. Purpose1

2. Cancellation1

3. Applicability1

4. Related Material2

5. How To Order3

6. Background And Definitions3

7. Authorization To Use Data link Communications In Flight Operations8

8. Flightcrew Qualification For Use Of Data link Communications10

9. Other Operational Issues16

10. Maintenance17

11. Data link Communications Operational Use18

12. Data Link Event Reporting20

13. Foreign Air Carriers21

APPENDIX 1 SAMPLE DATA LINK EVENT REPORTING INFORMATION (1 page)1

APPENDIX 2. DATA LINK COMMUNICATIONS MINIMUM REQUIREMENT

LIST (MEL) AND MASTER MINIMUM EQUIPMENT LIST (MMEL)

PROVISIONS (2 pages)1

APPENDIX 3. PART 129 PROVISIONS FOR USE OF DATA LINK

IN U.S. AIRSPACE (1 page)1

APPENDIX 4. ACRONYMS AND ABBREVIATIONS (2 pages)1

Page i (and ii)

1. PURPOSE. This advisory circular (AC) presents various methods for operators of differing data link systems to meet international standards set by the International Civil Aviation Organization (ICAO) and the Regional Airspace Authorities. The FAA notes that there is presently no requirement in Title 14 of the Code of Federal Regulations to have data link communications when operating in the National Airspace System (NAS). Instead, the regulations in Title 14 govern radio communication systems, and nothing in this AC absolves an operator from the requirement to have and use a voice communication system when operating in the NAS. However, operators that choose to use a data link system (in addition to the required voice communication system) must obtain FAA design approval and a revision to their Operating Specifications. Thus, the FAA is issuing this AC is to present the consensus of the aviation community regarding acceptable methods, procedures, and training for users of data link systems.

The original advisory circular, AC 120-70, was applicable to Aeronautical Telecommunication Network (ATN) VHF Data Link (VDL) Mode 2 communication systems. The Future Air Navigation System (FANS 1/A) system used in Oceanic and Remote airspace is an analog system which communicates over Aircraft Communications Addressing and Reporting System (ACARS). Guidance is needed for the operation of both systems and therefore the requirement for this revision.

2. CANCELLATION. AC 120-70 dated February 17, 2000, Initial Air Carrier Operational Approval for Use of Digital Communication System, is cancelled.

3. APPLICABILITY. This AC applies to aircraft and air carriers operating under parts 121, and 135, other organizations conducting training approved in accordance with part 121 (e.g., training centers or aircraft manufacturers), operators under part 125, and foreign air carriers conducting operations in United States airspace under part 129. This AC describes the process for obtaining operational authorization for data link communication systems, acceptable methods for training and maintenance, and operational policies for use. In addition, it describes appropriate actions in the event of an exceptional air traffic control (ATC) data link communications event, and criteria for foreign operator use of data link communications in U.S.

airspace. This AC may be applied to operators conducting operations under 14 CFR part 91.

This AC does not address the use of data link communications for specific ATS applications such as ATIS, PDC, and DDTC, which are information services not directly related to aircraft separation.

The Data Link System should comply with International Standards and Recommended Practices and Procedures for Air Navigation Services, Annex 10 to the Convention on International Civil Aviation, Aeronautical Telecommunications, Volume II, Communications Procedures including those with PANS status, Chapter 8, Aeronautical Mobile Service – Data Link Communications, Sixth Edition October 2001. This AC is consistent with-Volume III, Part I, Digital Communication Systems, Chapter 3, Aeronautical Telecommunication Network (ATN).

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4. RELATED MATERIAL.

a. Title 14 Code of Federal Regulations (14 CFR). The following 14 CFR parts are applicable to the communications systems and applications covered in this document: parts 21, 23, 25, 27, 29, 43, 91, 121, 125, 129 and 135.

b. Advisory Circulars. The following AC provides additional information that may assist in the operational authorization of data link communications systems:

• AC 20-140, Guidelines for Design Approval of Aircraft Data Communications Systems

c. International Civil Aviation Organization (ICAO) documents:

(1) Annex 10 to the ICAO Convention (Standards and Recommended Practices – SARP’s), Volume III, Part 1, Data link Data Communications Systems.

(2) Document 4444 (PANS/ATM), Procedures for Air Navigation Services - Rules of the Air and Air Traffic Services.

(3) Annex 6 to the ICAO Convention Operations of Aircraft.

(4) Annex 11 to the ICAO Convention Air Traffic Services.

(5) Document 7030, Regional Supplementary Procedures.

d. FAN’s Interoperability Team and FAN’s Interoperability Group Global Document:

• FAN’s Operations Manual

e. The following RTCA documents are available from RTCA Inc., 1140 Connecticut Avenue, NW. Suite 1020, Washington, DC 20036:

(1) DO-210C, Minimum Operational Performance Standards for Aeronautical Mobile Satellite Service (AMSS avionics).

(2) DO-212, Minimum Operational Performance Standards for Airborne Automatic Dependent Surveillance (ADS) Equipment.

(3) DO-215A, Guidance on Aeronautical Mobile Satellite Service (AMSS) End-to-End System Performance.

(4) DO-219, Minimum Operational Performance Standards for ATC Two-Way Data Link Communications (Applications).

(5) DO-224, Signal-in-Space Minimum Aviation System Performance Standards for Advanced VHF Data link Communications.

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(6) DO-231, Design Guidelines and Recommended Standards for the Internet working, Implementation and Use of AMS(R)S.

(7) DO-239, Minimum Operational Performance Standards for Traffic Information Services (TIS) Data Link Communications.

(8) DO-240, Minimum Operating Performance Standards for Aeronautical Telecommunication Network (ATN) Avionics.

(9) DO-242, Minimum Aviation System Performance Standards for Automatic Dependent Surveillance Broadcast (ADS-B).

(10) DO-243, Guidance for Initial Implementation of Cockpit Display of Traffic Information.

(11) DO 264, Guidelines for Approval of the Provision and Use of Air Traffic Services Supported by Data Communications.

f. The following SAE documents are available from SAE International, Customer Sales, 400 Commonwealth Avenue, Warrendale, PA, 15096:

(1) ARP 4754, Certification Considerations for Highly-Integrated or Complex Aircraft Systems.

(2) ARP 4761, Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment.

5. HOW TO ORDER.

a. A copy of this AC and other ACs mentioned herein may be obtained from:

U.S. Department of Transportation Subsequent Distribution Office, SVC-121.23 Ardmore East Business Center 3341 Q 75th Ave Landover, MD 20785

b. Identify this publication in your order as Federal Aviation Administration (FAA) Advisory Circular (AC 120-70A), Operational Authorization Process For Use Of Data link Communication Systems.

6. BACKGROUND AND DEFINITIONS.

a. Data Link Implementation. Data link applications are being implemented in flight operations and other operations on a widespread basis (e.g., PDC, D-ATIS, FANS-1 CPDLC, FIS/TIS, and ADS). Data link applications operate without any specific knowledge by the user as to whether a satellite, VHF, or HF air/ground data link medium network service is in use.

However, these applications may be limited by the level of end-to-end data link service Par 4 Page 3

implementation in use. (e.g., ACARS, FANS-1 ACARS/ARINC 622, CNS/ATM-1). This AC provides information for U.S. operators, aircraft and data link manufacturers, various inspectors, foreign air carriers operating in U.S. airspace, and other aviation organizations regarding a means acceptable to the FAA for the use of data link systems in ATS communications. This information is intended to facilitate the operational authorization of data link systems, promote timely and comprehensive program implementation, encourage development of standard practices for the application of data link techniques, and provide an appropriate response to exceptional data link events.

b. Definitions. Certain definitions in this AC are taken from other FAA materials. Other definitions are unique to this AC, and their application is limited to use with data link systems.

(1) Aircraft Certification Office (ACO). FAA offices responsible for the determination of aircraft airworthiness and other issues related to parts 21, 23, 25, 33, and other airworthiness rules. ACOs issue Type Certificates (TC), and Supplemental Type Certificates (STC), and are responsible for the technical assessment of service difficulties and Airworthiness Directives (AD).

(2) Aircraft Evaluation Group (AEG). FAA offices responsible for operational aspects of newly certificated, modified, or "in-service" aircraft. AEGs establish FAA criteria for pilot qualification as it relates to Flight Standardization Board (FSB) and initial aircraft certification, AEGs are also responsible for minimum equipment lists (MEL), initial airworthiness, and other operationally related regulation, including 14 CFR parts 43, 61, 91, 121, 135.

(3) Certificate-Holding District Office (CHDO). A Flight Standards office responsible for the administration of part 119 certificate authority for operations conducted under parts 121 or 135 for a particular certificate holder.

(4) Air Traffic Data Link Service. A data communication capability comprising air/ground and ground/ground data network services, specified data link message sets and protocols, aircraft equipment, ATS Facility equipment, and operational procedures intended to provide primary or supplemental ATS communications without reversion to voice procedures under most circumstances.

(5) Data Link Event. For the purpose of this AC, a Data Link Event is one or more of the following occurrences or situations related to data link:

• In-flight traffic conflicts or potential conflicts as determined by a flightcrew member in which use of a data link service is suspected to be contributing cause.

• Near mid-air collisions (NMAC) in which the use of a data link service is suspected to be a contributing cause.

• Data link system performance below that of normal operation.

• ATC operational error involving a data link-equipped aircraft.

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• Other occurrences or situations in which use of a data link service is suspected to compromise continued operational safety. Loss of standard ATC separation resulting from a procedure or maneuver where a data link transaction, failure, or unmonitored error is suspected to be a factor.

• Use of the data link service that caused excessive crew workload.

• A data link service that provides reasonable information but is subsequently verified to be erroneous.

• An excursion of more than 500 feet from an assigned flight level/altitude, or a lateral/longitudinal deviation exceeding ATS minimum separation criteria in which use of a data link service is suspected to be a contributing cause.

(6) Data Link Service Academic Training (as applied within this AC). Training that exclusively addresses knowledge requirements (rather than skills), and is usually related to achieving satisfactory knowledge of data link service concepts, systems, limitations, or procedures. The academic training on data link services is generally accomplished using a combination of classroom methods (stand up instruction, slide/tapes, computer-based instruction (CBI), tutorial, etc.), flight manual information, bulletins, or self-study. See paragraph 8b for an expanded explanation of the recommended curriculum.

(7) Data Link Service Use Training. This is training that addresses all of the skills related to the operational use of data link services including the knowledge and skills needed to receive information provided by data link services, and appropriately accept, reject, cancel, or defer a response to that information. In addition, this training includes the knowledge and skills needed to load, store, formulate, and request information from the data link service.

(8) Data Link System. A general term referring to data link digital or analog based systems. At the present time the digital operation is known as VDL–Mode 2 system. The analog operation is known as the FANS system. The FANS (1/A) system uses both digital and analog components. The data link applications are digital and binary encoded, and then processed by the ACARS convergence function (ACF) for transmission over a character-oriented network.

(9) Flight Standards District Office (FSDO). An FAA field office serving an assigned geographical area and staffed with Flight Standards personnel who serve the aviation industry and the general public on matters relating to the licensing of aviation personnel, certification of aircraft and operational authorization of air carriers, commuter and general aviation operations.

(10) Flight Standards Board (FSB). The FAA board responsible for establishing or revising crew qualification requirements (e.g., training, checking, currency, and type rating(s)) for specific aircraft). FSBs are established for each large turbojet and turboprop aircraft type used in air transportation, as well as other part 25 aircraft, transport category multi-engine helicopters, and large multi-engine piston aircraft.

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(11) Follow-on STC (as related to data link communications). A data link communications STC other than as described in item (13) below for an "Initial TC/STC." The following examples are considered to be "follow-on" STCs:

• A previously approved data link communications installation, installed in a subsequent type or model aircraft.

• Changes of display configuration (FMS/data link display), supporting system (EICAS/ECAM) or other aircraft interface (DFDR, etc.).

(12) Initial TC/STC (as related to data link communications). The first FAA data link communications airworthiness approval (in accordance with a TC or STC) of any one or combination of the following components: a data link processor and/or management unit, data link communications avionics.

NOTE: Previously approved data link communications systems, may require an initial TC/STC, if the part number of any of the above components changes due to a significant modification that changes, the system.

(13) Maintenance Review Board (MRB). An FAA board responsible for establishing maintenance requirements for a specific aircraft type. MRB requirements are usually formulated in conjunction with information provided by the manufacturer and prospective operators through industry working groups. FAA CHDOs apply MRB requirements in reviewing and approving each carrier's proposed maintenance program.

(14) Master Minimum Equipment List (MMEL). An FAA document listing stipulations in accordance with 14 CFR §§ 121.628 and 135.179 that provides authorization for the continuation of flight beyond a terminal point with certain equipment inoperative. AEGs develop MMELs in conjunction with a Flight Operation Evaluation Board (FOEB) established for each aircraft type. The MMEL, which is associated with a particular type of aircraft, serves as the basis for MELs, which are associated with an air carrier’s operation of that aircraft type.

(15) National Airspace System (NAS). Information on the NAS related to operations and use of air traffic data link services can be found in Aeronautical Information Publication, Airmen’s Information Manual, Notice to Airmen, Jeppesen Charts, or similar resources. The common network of U.S. airspace is comprised of the following:

• Air navigation facilities

• Equipment and services

• Airports

• Aeronautical charts

• Rules Page 6 Par 7

• Regulations

• Procedures

• Technical information

• Manpower

• Materials

• System components shared jointly with the military

(16) National Simulator Evaluation Team (NSET). Team of FAA operations specialists responsible for evaluating flight simulators to aid Principal Operations Inspectors (POI) in approving those simulators in accordance with regulatory requirements (e.g., NSET evaluations support POI approval of a particular simulator for use in a specific part 121 program).

(17) Principal Inspector (PI). Refers to one of three FAA principal inspectors:

principal avionics inspector (PAI), principal operations inspector (POI), or principal maintenance inspector (PMI).

• Principal Avionics Inspector (PAI). The FAA inspector assigned responsibility for overseeing all avionics issues relative to a specific operator, including input to training programs, Operations Specifications, MEL requests, etc.

• Principal Operations Inspector (POI). The FAA inspector assigned responsibility for overseeing all operational issues relative to a specific operator, including approval of training programs, Operations Specifications approval, maintenance programs, MEL change requests, etc.

• Principal Maintenance Inspector (PMI). The FAA inspector assigned responsibility for overseeing all maintenance issues relative to a specific operator, including input to training programs approved maintenance programs, Operations Specifications, MEL requests, etc.

(18) Supplemental Type Certificate (STC). An FAA certificate certifying that modifications to the respective aircraft, engines, or other components meet airworthiness requirements of the regulations.

(19) Type Certificate (TC). An FAA certificate certifying that the respective aircraft, engines, or other components meet airworthiness requirements of the regulations.

7. AUTHORIZATION TO USE DATA LINK COMMUNICATIONS IN FLIGHT OPERATIONS.

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AC 120-70A

a. General.

(1) Installation of a data link communication system requires FAA design approval of changes to the aircraft's type design by amending the TC or issuing an STC. However, approval to install a TC’d or STC’d data link communications system does not constitute approval to use the system. Prior to using the system, the operator must request a revision to their Operations Specifications to ensure that the system is used in accordance with international standards and requirements and in a manner that is acceptable to the FAA. A revision to the Operations Specifications includes specific authorizations, training and maintenance programs, manuals, operational procedures, MELs, and other such areas necessary for safe and effective use of data link communications. In addition, the service must be capable of meeting international standards for a specific route.

(2) Responsibilities of various FAA offices regarding data link communications. FAA ACOs approve changes to a type design or issuance of STCs. FAA AEGs formulate operational criteria for specific aircraft types related to training, checking, maintenance, MMELs or other operational issues, as necessary. FAA uses information developed by AEGs to review a particular operator's programs. CHDOs approve particular Operations Specifications, letters of authorizations, operator's training, maintenance programs, operational procedures, and MELs, if they are consistent with criteria specified in this Advisory Circular, Aeronautical Information Manual (AIM), MMELs, FSB reports, MRB reports, and policy guidance from Flight Standards Service AFS-200, AFS-300, AFS-400 and AFS-800.

b. Design Approval of Aircraft Data Communications Systems. Guidelines of design approval of aircraft data communication and SATCOM voice systems and applications primarily used for ATS are provided in FAA AC 20-140 or equivalent.

c. Operational Authorization. Criteria for data link operational authorization are determined by the communication requirements specified for the intended operation.

(1) Data link Communications Authorization Criteria. Operational authorizations are based on criteria in this AC, and may also include criteria outlined in, training, maintenance, MMEL, or other operationally related criteria formulated by AEGs. If criteria for training or checking are other than as specified in this AC, the criteria may be found in FSB reports applicable to a particular aircraft type. Provisions for dispatch with inoperative equipment are specified by the MMEL for each aircraft type. Maintenance requirements are identified by this AC, unless otherwise described by a MRB report for a specific aircraft type, or in FAA-approved maintenance instructions identified in conjunction with an STC or manufacturer's Service Bulletin.

(2) Data Link Communications Authorization Methods. FAA Flight Standards provides operational approval of data link communications training programs, checklists, operations manuals, training manuals, maintenance programs, MELs, and other pertinent documents or document revisions applicable to the particular air carrier. Operators' data link communications programs are usually approved for each specific aircraft type. However, Page 8 Par 7