+-----------------------------------+----------------------------------+
| ![](media/image1.                 | **Advisory**                     |
| wmf){width="0.3798611111111111in" |                                  |
| height="0.3597222222222222in"}    | **Circular**                     |
|                                   |                                  |
| U.S. Department                   |                                  |
|                                   |                                  |
| of Transportation                 |                                  |
|                                   |                                  |
| Federal Aviation                  |                                  |
|                                   |                                  |
| ### **Administrati                |                                  |
| on** {#administration .Paragraph} |                                  |
|                                   |                                  |
| **DRAFT**                         |                                  |
+-----------------------------------+----------------------------------+

+-----------------------------------+-------------------+--------------+
| ### Subject: Guidelin             | ### Date:         | ### AC       |
| es for Design Approval of Aircraf |                   |  No. 20-140A |
| t Data Link Communication Systems | **Initiated By:** |              |
|                                   | AIR-100           | **Change:**  |
+-----------------------------------+-------------------+--------------+

# What is the Purpose of this Advisory Circular (AC)?  {#what-is-the-purpose-of-this-advisory-circular-ac .Style-Heading-1-+-(Latin)-Times-New-Roman-Before:--0-pt-After:--0...}

a.  The guidance in this advisory circular (AC) provides one acceptable
    means of compliance, but not the only means, for type design
    approval of aircraft that has a data link system installed.

b.  Use the guidance in this AC to gain approval for type certificates
    (TC) and supplemental type certificates (STC) involving aircraft
    data link systems. Also, it will facilitate standardization of these
    approvals among the aircraft certification offices (ACOs) in their
    assessment of aircraft data link systems for design approval.

c.  This AC was developed in consideration of the International Civil
    Aviation Organization (ICAO) Annexes and guidance material, RTCA
    Inc. documents (RCTA/DO) and European Organization for Civil
    Aviation Equipment (EUROCAE) related documents (ED). It is based on
    published safety and performance (SPR) standards and
    interoperability (INTEROP) standards for aircraft data link systems
    in different types of operating environments.

d.  This AC is not mandatory and does not constitute a regulation. It is
    issued to provide guidelines and to outline a means of showing that
    an aircraft data link system complies with airworthiness standards
    contained in Title 14 of the Code of Federal Regulations (14 CFR),
    chapter 1, subchapter C.

e.  This AC provides airworthiness requirements for the type design
    approval of aircraft with data link system installed. AC
    120‑70B,*Operational Authorization Process for use of Data Link
    Communication System,* provides guidelines for the operational
    authorization needed to use the data link capability.

# **Who Does this AC affect?** 

This AC provides guidelines for applicants seeking design approval of
aircraft data link systems used for communication supporting air traffic
services (ATS).

# **Guidance on Standards Development and Compliance**.

a.  RTCA/DO-264/ED-78A, *Guidelines for Approval of the Provision and
    Use of Air Traffic Services supported by Data Communications*, dated
    December 14, 2000, provides guidance on how to develop standards for
    an operational data link system and show that the data link
    implementation complies with the standards. These guidelines take
    into consideration the different types of aircraft data link
    systems, the ground infrastructure, and the operational use of the
    data link capability.

b.  RTCA/ DO-264/ED-78A, Annex A, *Compliance Matrix*, provides a
    summary of the objectives that defines the evidence appropriate for
    each of the approval types, such as design approval per the guidance
    of this AC, or operational authorization per the guidance of AC
    120-70B. This AC recognizes Annex A as a verification tool to
    achieve traceability to the means used to show compliance, and to
    ensure that all objectives relevant to the design approval of the
    aircraft data link system have been met. Complying with the
    objectives of this AC and using the standards specified in Tables 1
    and 2 are considered to satisfy that criteria and
    RTCA/DO-264/ED-78A, especially sections 5 and 6, and the related
    Annex A Aircraft Type Design Approval column.

c.  For standards that are recognized in this AC, you will need to
    consider the intended uses of the aircraft data link system, choose
    the appropriate standards, and ensure your data link system complies
    with the requirements. As stated in RTCA/DO-264/ED-78A, you might
    need to show that the development and qualification of the aircraft
    data link system complies with the objectives in RTCA/DO‑264/ED‑78A,
    section 5 and section 6, as deemed relevant by Annex A.

d.  For operating environments that are not defined in Table 1, an
    applicant will need to demonstrate applicability of existing
    standards or provide the appropriate safety and/or interoperability
    standards that comply with the objectives provided in DO‑264/ED‑78A,
    section 4. These standards are needed to determine the requirements
    for the aircraft data link system based on the intended use. See
    also paragraph 5.e.

# **Definitions for Different Types of Data Link Systems and Operations**.

a.  Table-1 provides the definitions for different types of data link
    systems and operations based on standards. For each type of data
    link system, a row is provided to assign a designator to a
    particular aircraft capability, and correlate it to the applicable
    operating environment. The applicable operating environment is
    characterized by the type of airspace, the capability of the ATS
    unit, and the use for which that aircraft capability is intended.
    Table‑1a provides the definitions for different types of
    sub-networks that support the data link systems defined in Table‑1.
    For each type of sub-network, a row is provided to assign a
    designator to a particular sub-network. The capability and uses are
    characterized in terms of the data link applications and
    sub-networks. The aircraft and sub-network designators are used in
    the rotorcraft/airplane flight manual (R/AFM) to convey the
    functional and interoperability aspects of the aircraft data link
    system needed to support operations.

b.  The applicable standards provide the safety and performance
    requirements (denoted by SPR) and the interoperability requirements
    (denoted by INTEROP) for the data link applications and the
    sub-networks (denoted by a designator for the sub-network). These
    standards provide requirements for the aircraft data link system and
    its operating environment. Table‑2 and Table‑2a provide the the
    criteria for the aircraft data link system.

c.  Use Table-1 and Table‑1a to identify the applicable operating
    environment(s) and intended uses for your specific aircraft data
    link system. An aircraft data link system may support any
    combination of aircraft designators in the table. For an aircraft
    data link system that combines aeronautical telecommunications
    network (ATN) B1 and future navigation system (FANS) 1/A
    capabilities that can be used on the same flight, you will need to
    develop an interoperability standard per paragraph 3.d.

**Table‑1, Definitions for Different Types of Data Link Systems and
Operations**

+---+-------+---------+-------+------------------+-------------------+
| R | Air   | Op      |       |                  | **Applicable      |
| o | craft | erating |       |                  | Standards**       |
| w | Data  | Envi    |       |                  |                   |
| \ | Link  | ronment |       |                  |                   |
| # | S     |         |       |                  |                   |
|   | ystem |         |       |                  |                   |
+===+=======+=========+=======+==================+===================+
|   |       | Type of | ATS   | Capability and   |                   |
|   |       | A       | Unit  | Uses             |                   |
|   |       | irspace | S     |                  |                   |
|   |       |         | ystem |                  |                   |
+---+-------+---------+-------+------------------+-------------------+
| 1 | ATN   | Cont    | ATN   | Supplemental ATC | a                 |
|   | B1    | inental | B1    | communications:  | )  DO-290/ED-120, |
|   |       |         |       |                  |     Chg 1 and Chg |
|   |       | (Do     |       | -   CM           |     2,            |
|   |       | mestic) |       |     application  |     Continental   |
|   |       |         |       |     supports     |     SPR Standard  |
|   |       |         |       |     DLIC data    |                   |
|   |       |         |       |     link service | b)                |
|   |       |         |       |                  |  DO-280B/ED-110B, |
|   |       |         |       | -   CPDLC        |     ATN B1        |
|   |       |         |       |     application  |     INTEROP       |
|   |       |         |       |     supports     |     Standard      |
|   |       |         |       |     ACM, ACL,    |                   |
|   |       |         |       |     and AMC data | c)  Sub-network   |
|   |       |         |       |     link         |     standards for |
|   |       |         |       |     services     |     VDL M2 (See   |
|   |       |         |       |                  |     Table‑1a)     |
|   |       |         |       | [Note            |                   |
|   |       |         |       | 1]{.underline}:  |                   |
|   |       |         |       | DCL, DSC,        |                   |
|   |       |         |       | D-ATIS, and      |                   |
|   |       |         |       | FLIPCY data link |                   |
|   |       |         |       | services are not |                   |
|   |       |         |       | supported.       |                   |
+---+-------+---------+-------+------------------+-------------------+
| 2 | FANS  | Cont    | ATN   | Same as Row 1,   | Same as for Row   |
|   | 1/A+  | inental | B1    | except:          | 1, plus:          |
|   |       |         | -FANS |                  |                   |
|   |       | (Do     | 1/A   | -   Uses AFN     | a                 |
|   |       | mestic) |       |     application  | )  DO-305/ED-154, |
|   |       |         |       |     for DLIC     |     FANS 1/A --   |
|   |       |         |       |     data link    |     ATN INTEROP   |
|   |       |         |       |     service      |     Standard      |
|   |       |         |       |                  |     (Applies only |
|   |       |         |       | -   For CPDLC    |     to ATS Unit,  |
|   |       |         |       |     application, |     except see    |
|   |       |         |       |     UM 215, TURN |     Note 2)       |
|   |       |         |       |                  |                   |
|   |       |         |       |    \[direction\] | ```{=html}        |
|   |       |         |       |     \[degrees\]  | <!-- -->          |
|   |       |         |       |     is not       | ```               |
|   |       |         |       |     supported    | d)                |
|   |       |         |       |                  |  DO-258A/ED-100A, |
|   |       |         |       | [Note            |     FANS 1/A      |
|   |       |         |       | 2]{.underline}:  |     INTEROP       |
|   |       |         |       | FANS 1/A         |     Standard      |
|   |       |         |       | aircraft will    |     (Applies only |
|   |       |         |       | require use of   |     to aircraft)  |
|   |       |         |       | DM67 \[free      |                   |
|   |       |         |       | text\] to mimic  | e)  Sub-network   |
|   |       |         |       | certain message  |     standards for |
|   |       |         |       | elements per     |     VDL M2 (See   |
|   |       |         |       | DO‑290/ED‑120    |     Table‑1a)     |
|   |       |         |       | Chg 1 and 2. See |                   |
|   |       |         |       | DO‑305/ED‑154,   |                   |
|   |       |         |       | paragraph        |                   |
|   |       |         |       | 4.2.13.2.        |                   |
|   |       |         |       |                  |                   |
|   |       |         |       | [Note            |                   |
|   |       |         |       | 3]{.underline}:  |                   |
|   |       |         |       | In accordance    |                   |
|   |       |         |       | with             |                   |
|   |       |         |       | DO-290/ED-120,   |                   |
|   |       |         |       | Chg 1 and Chg 2, |                   |
|   |       |         |       | FANS 1/A         |                   |
|   |       |         |       | aircraft will    |                   |
|   |       |         |       | require use of a |                   |
|   |       |         |       | message latency  |                   |
|   |       |         |       | timer per        |                   |
|   |       |         |       | DO‑258A/ED‑100A, |                   |
|   |       |         |       | paragraph        |                   |
|   |       |         |       | 4.6.6.9 and is   |                   |
|   |       |         |       | denoted by a "+" |                   |
|   |       |         |       | appended to the  |                   |
|   |       |         |       | "FANS 1/A"       |                   |
|   |       |         |       | label.           |                   |
+---+-------+---------+-------+------------------+-------------------+
| 3 | FANS  | Oceanic | FANS  | Normal means of  | a                 |
|   | 1/A+  | and     | 1/A   | ATC              | )  DO‑306/ED‑122, |
|   |       | remote  |       | communication    |     Oceanic SPR   |
|   | or    |         |       | uses AFN and     |     Standard      |
|   |       |         |       | CPDLC            |                   |
|   | FANS  |         |       | applications for | ```{=html}        |
|   | 1/A   |         |       | DCPC             | <!-- -->          |
|   |       |         |       |                  | ```               |
|   |       |         |       | Eligible for:    | f)                |
|   |       |         |       |                  |   DO‑258A/ED‑100A |
|   |       |         |       | -   RCP 240      |     (or earlier   |
|   |       |         |       |     operations   |     versions),    |
|   |       |         |       |     via any      |     FANS 1/A      |
|   |       |         |       |     sub-network  |     INTEROP       |
|   |       |         |       |     listed in    |     Standard      |
|   |       |         |       |     Table‑1a,    |                   |
|   |       |         |       |     except for   | g)  Sub-network   |
|   |       |         |       |     HFDL         |     standards for |
|   |       |         |       |                  |     selected      |
|   |       |         |       | -   RCP 400      |     sub-networks. |
|   |       |         |       |     operations   |     (See          |
|   |       |         |       |     via any      |     Table‑1a)\    |
|   |       |         |       |     sub-network  |     \             |
|   |       |         |       |     listed in    |     Note: Allows  |
|   |       |         |       |     Table‑1a.    |     use of one or |
|   |       |         |       |                  |     more          |
|   |       |         |       | -   No RCP       |     sub-networks. |
|   |       |         |       |     operations   |     See           |
|   |       |         |       |     via any      |     Capability    |
|   |       |         |       |     sub-network  |     and Uses      |
|   |       |         |       |     listed in    |     column for    |
|   |       |         |       |     Table‑1a.    |     indications,  |
|   |       |         |       |                  |     alerts and    |
|   |       |         |       | [Note            |     sub-networks  |
|   |       |         |       | 4]{.underline}:  |     that are      |
|   |       |         |       | Aircraft         |     eligible for  |
|   |       |         |       | capability that  |     intended      |
|   |       |         |       | supports         |     operations.   |
|   |       |         |       | multiple         |                   |
|   |       |         |       | RCP type         |                   |
|   |       |         |       | operations needs |                   |
|   |       |         |       | to include       |                   |
|   |       |         |       | appropriate      |                   |
|   |       |         |       | indications      |                   |
|   |       |         |       | and/or alerts to |                   |
|   |       |         |       | enable the       |                   |
|   |       |         |       | flight crew to   |                   |
|   |       |         |       | notify ATC when  |                   |
|   |       |         |       | aircraft         |                   |
|   |       |         |       | equipment        |                   |
|   |       |         |       | failures result  |                   |
|   |       |         |       | in the           |                   |
|   |       |         |       | aircraft's       |                   |
|   |       |         |       | ability to no    |                   |
|   |       |         |       | longer meet its  |                   |
|   |       |         |       | criteria for any |                   |
|   |       |         |       | of the RCP       |                   |
|   |       |         |       | types, per       |                   |
|   |       |         |       | DO-306/ED‑122,   |                   |
|   |       |         |       | paragraph        |                   |
|   |       |         |       | 5.2.6.a) and     |                   |
|   |       |         |       | 5.2.6.b).        |                   |
|   |       |         |       |                  |                   |
|   |       |         |       | Uses ADS‑C       |                   |
|   |       |         |       | application for  |                   |
|   |       |         |       | automatic        |                   |
|   |       |         |       | position         |                   |
|   |       |         |       | reporting. See   |                   |
|   |       |         |       | required         |                   |
|   |       |         |       | performance for  |                   |
|   |       |         |       | ADS‑C            |                   |
|   |       |         |       | application per  |                   |
|   |       |         |       | DO‑306/ED‑122.   |                   |
|   |       |         |       | ADS‑C            |                   |
|   |       |         |       | application over |                   |
|   |       |         |       | HFDL (See        |                   |
|   |       |         |       | Table‑1a) not    |                   |
|   |       |         |       | eligible for     |                   |
|   |       |         |       | reduced          |                   |
|   |       |         |       | longitudinal     |                   |
|   |       |         |       | separation.      |                   |
+---+-------+---------+-------+------------------+-------------------+
| 4 | FANS  | Oceanic | CADS  | No CPDLC         | a                 |
|   | 1/A+  | and     |       | application      | )  DO‑306/ED‑122, |
|   |       | remote  |       |                  |     Oceanic SPR   |
|   | or    |         |       | Uses ADS‑C       |     Standard      |
|   |       |         |       | application for  |                   |
|   | FANS  |         |       | automatic        | ```{=html}        |
|   | 1/A   |         |       | position         | <!-- -->          |
|   |       |         |       | reporting. See   | ```               |
|   |       |         |       | required         | h)                |
|   |       |         |       | performance for  |   DO-258A/ED‑100A |
|   |       |         |       | ADS‑C            |     (or earlier   |
|   |       |         |       | application per  |     version),     |
|   |       |         |       | DO‑306/ED‑122.   |     FANS 1/A      |
|   |       |         |       |                  |     INTEROP       |
|   |       |         |       |                  |     Standard      |
|   |       |         |       |                  |     (Applies only |
|   |       |         |       |                  |     to aircraft). |
|   |       |         |       |                  |                   |
|   |       |         |       |                  | i)  CADS Common   |
|   |       |         |       |                  |                   |
|   |       |         |       |                  |    Specification, |
|   |       |         |       |                  |     Version 2.0,  |
|   |       |         |       |                  |     approved ICAO |
|   |       |         |       |                  |     NAT FIG/10,   |
|   |       |         |       |                  |     Paris, March  |
|   |       |         |       |                  |     29-April 2,   |
|   |       |         |       |                  |     2004 (Applies |
|   |       |         |       |                  |     only to ATS   |
|   |       |         |       |                  |     unit)         |
|   |       |         |       |                  |                   |
|   |       |         |       |                  | j)  Sub-network   |
|   |       |         |       |                  |     standards     |
|   |       |         |       |                  |     same as row   |
|   |       |         |       |                  |     3.            |
+---+-------+---------+-------+------------------+-------------------+
| 5 | FMS   | Oceanic | CFRS  | No CPDLC         | a                 |
|   | WPR   | and     |       | application      | )  DO‑306/ED‑122, |
|   |       | remote  |       |                  |     Oceanic SPR   |
|   |       |         |       | Uses FMS WPR     |     Standard      |
|   |       |         |       | application for  |                   |
|   |       |         |       | automatic        | ```{=html}        |
|   |       |         |       | position         | <!-- -->          |
|   |       |         |       | reporting. See   | ```               |
|   |       |         |       | required         | k)  ARINC 702A,   |
|   |       |         |       | performance for  |     Advanced      |
|   |       |         |       | FMS WPR          |     Flight        |
|   |       |         |       | application per  |     Management    |
|   |       |         |       | DO‑306/ED‑122.   |     Computer      |
|   |       |         |       |                  |     System        |
|   |       |         |       |                  |     (Applies only |
|   |       |         |       |                  |     to aircraft). |
|   |       |         |       |                  |                   |
|   |       |         |       |                  | l)  CFRS Common   |
|   |       |         |       |                  |                   |
|   |       |         |       |                  |    Specification, |
|   |       |         |       |                  |     Version 2.0,  |
|   |       |         |       |                  |     approved ICAO |
|   |       |         |       |                  |     NAT FIG/10,   |
|   |       |         |       |                  |     Paris, March  |
|   |       |         |       |                  |     29-April 2,   |
|   |       |         |       |                  |     2004 (Applies |
|   |       |         |       |                  |     only to ATS   |
|   |       |         |       |                  |     unit).        |
|   |       |         |       |                  |                   |
|   |       |         |       |                  | m)  Sub-network   |
|   |       |         |       |                  |     standards     |
|   |       |         |       |                  |     same as row 3 |
+---+-------+---------+-------+------------------+-------------------+
| 6 | FANS  | Oceanic | FANS  | Same as row 4    | a                 |
|   | 1/A   | and     | 1/A   |                  | )  DO‑306/ED‑122, |
|   | ADS‑C | remote  |       |                  |     Oceanic SPR   |
|   |       |         | or    |                  |     Standard      |
|   |       |         |       |                  |                   |
|   |       |         | CADS  |                  | ```{=html}        |
|   |       |         |       |                  | <!-- -->          |
|   |       |         |       |                  | ```               |
|   |       |         |       |                  | n)                |
|   |       |         |       |                  |   DO-258A/ED‑100A |
|   |       |         |       |                  |     (or earlier   |
|   |       |         |       |                  |     version) FANS |
|   |       |         |       |                  |     1/A INTEROP   |
|   |       |         |       |                  |     Standard (If  |
|   |       |         |       |                  |     ATS unit is   |
|   |       |         |       |                  |     CADS, applies |
|   |       |         |       |                  |     only to       |
|   |       |         |       |                  |     aircraft)     |
|   |       |         |       |                  |                   |
|   |       |         |       |                  | o)  CADS Common   |
|   |       |         |       |                  |                   |
|   |       |         |       |                  |    Specification, |
|   |       |         |       |                  |     Version 2.0,  |
|   |       |         |       |                  |     approved ICAO |
|   |       |         |       |                  |     NAT FIG/10,   |
|   |       |         |       |                  |     Paris, March  |
|   |       |         |       |                  |     29-April 2,   |
|   |       |         |       |                  |     2004 (Applies |
|   |       |         |       |                  |     only to ATS   |
|   |       |         |       |                  |     unit when ATS |
|   |       |         |       |                  |     unit is       |
|   |       |         |       |                  |     CADS).        |
|   |       |         |       |                  |                   |
|   |       |         |       |                  | p)  Sub-network   |
|   |       |         |       |                  |     standards     |
|   |       |         |       |                  |     same as row   |
|   |       |         |       |                  |     3.            |
+---+-------+---------+-------+------------------+-------------------+
| 7 | ACARS | Conti   | ACARS | Departure        | a)  ED­85          |
|   |       | nental/ |       | clearance or     |                   |
|   |       | Oceanic |       | pre-departure    | ```{=html}        |
|   |       | and     |       | clearance        | <!-- -->          |
|   |       | remote  |       |                  | ```               |
|   |       |         |       | Data link --     | q)  ED-89         |
|   |       |         |       | automated        |                   |
|   |       |         |       | terminal         | r)  ED-106        |
|   |       |         |       | information      |                   |
|   |       |         |       | service          | s)  A623          |
|   |       |         |       |                  |                   |
|   |       |         |       | Oceanic          | t)  Sub-network   |
|   |       |         |       | clearance        |     standards     |
|   |       |         |       |                  |     same as row   |
|   |       |         |       |                  |     3.            |
|   |       |         |       |                  |                   |
|   |       |         |       |                  | [Note             |
|   |       |         |       |                  | 5]{.underline}:   |
|   |       |         |       |                  | Allows one or     |
|   |       |         |       |                  | more capability.  |
|   |       |         |       |                  | a) through d) are |
|   |       |         |       |                  | applicable for    |
|   |       |         |       |                  | selected          |
|   |       |         |       |                  | capabilities and  |
|   |       |         |       |                  | uses.             |
+---+-------+---------+-------+------------------+-------------------+

**Table‑1a, Definitions for sub-networks**

+------------------+---------------------------------------------------+
| Sub-network      | Applicable sub-network standards                  |
| designator       |                                                   |
+==================+===================================================+
| VDL M0/A         | A618-6 for air/ground protocol                    |
+------------------+---------------------------------------------------+
| VDL M2           | a)  DO-224 (MASPS)                                |
|                  |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | u)  A631-5                                        |
+------------------+---------------------------------------------------+
| HFDL             | a)  DO-265 (MASPS)                                |
|                  |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | v)  A753-3                                        |
+------------------+---------------------------------------------------+
| SATCOM           | a)  DO-270A (MASPS)                               |
| (Inmarsat)       |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | w)  A741P2-9                                      |
+------------------+---------------------------------------------------+
| SATCOM (Iridium) | a)  DO-270A (MASPS)                               |
|                  |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | x)  A741P2-9                                      |
|                  |                                                   |
|                  | y)  A761-2                                        |
+------------------+---------------------------------------------------+

**ACRONYMS:**

+-------------------+--------------------------------------------------+
| ACARS             | Aircraft communications addressing and reporting |
|                   | system                                           |
+-------------------+--------------------------------------------------+
| ACL               | ATC clearance                                    |
+-------------------+--------------------------------------------------+
| ACM               | ATC communications management                    |
+-------------------+--------------------------------------------------+
| ADS‑C             | Automatic dependent surveillance -- contract     |
|                   | (formerly ADS)                                   |
+-------------------+--------------------------------------------------+
| AFN               | ATS facility notification                        |
+-------------------+--------------------------------------------------+
| AMC               | ATC microphone check                             |
+-------------------+--------------------------------------------------+
| ATC               | Air traffic control                              |
+-------------------+--------------------------------------------------+
| ATN               | Aeronautical telecommunication network           |
+-------------------+--------------------------------------------------+
| ATN B1            | ATN baseline 1                                   |
+-------------------+--------------------------------------------------+
| ATS               | Air traffic service                              |
+-------------------+--------------------------------------------------+
| AVLC              | Aviation                                         |
|                   |                                                  |
|                   | VHF link control                                 |
+-------------------+--------------------------------------------------+
| CADS              | Centralized ADS-C system                         |
+-------------------+--------------------------------------------------+
| CFRS              | Centralized flight management computer waypoint  |
|                   | reporting system                                 |
+-------------------+--------------------------------------------------+
| CM                | Context management                               |
+-------------------+--------------------------------------------------+
| CPDLC             | Controller pilot data link communications        |
+-------------------+--------------------------------------------------+
| D-ATIS            | Data link - automated terminal information       |
|                   | service                                          |
+-------------------+--------------------------------------------------+
| DCL               | Departure clearance                              |
+-------------------+--------------------------------------------------+
| DCPC              | Direct controller-pilot communications           |
+-------------------+--------------------------------------------------+
| DLIC              | Data link initiation capability                  |
+-------------------+--------------------------------------------------+
| DSC               | Downstream clearance                             |
+-------------------+--------------------------------------------------+
| FANS              | Future air navigation system                     |
+-------------------+--------------------------------------------------+
| FLIPCY            | Flight Plan Consistency                          |
+-------------------+--------------------------------------------------+
| FMS WPR           | Flight management system waypoint position       |
|                   | reporting                                        |
+-------------------+--------------------------------------------------+
| HF                | High frequency                                   |
+-------------------+--------------------------------------------------+
| HFDL              | HF data link                                     |
+-------------------+--------------------------------------------------+
| INTEROP           | Interoperability                                 |
+-------------------+--------------------------------------------------+
| NAT FIG           | North Atlantic FANS 1/A Implementation Group     |
+-------------------+--------------------------------------------------+
| OCL               | Oceanic clearance                                |
+-------------------+--------------------------------------------------+
| RCP               | Required communication performance               |
+-------------------+--------------------------------------------------+
| SPR               | Safety and performance                           |
+-------------------+--------------------------------------------------+
| VDL M2            | VHF data link mode 2                             |
+-------------------+--------------------------------------------------+
| VHF               | Very high frequency                              |
+-------------------+--------------------------------------------------+

**5. Means of Compliance for the Aircraft Data Link System**.

a.  The means of compliance provided in this AC are described in terms
    of :

-   Standards -- that provide functional, safety, performance, and
    interoperability criteria for the aircraft data link system, and

-   Objectives -- that are satisfied by the processes used to develop
    and qualify the aircraft data link system.

b.  Table‑2 and Table‑2a refer to the appropriate criteria for the
    aircraft data link system for each of the data link definitions
    provided in Table‑1 and Table‑1a.

c.  The criteria provided in each row of Table‑2 and Table‑2a are
    entirely applicable to the aircraft data link system for the row or
    the capabilities and the sub-networks selected.

d.  The design approval for the aircraft data link system is applicable
    when the assumptions are valid for the intended use. Include in the
    R/AFM or other appropriate certification document any relevant
    information needed to support the operational authorization. See
    paragraph 8 in this AC.

e.  You may request changes from the provisions of this AC. Your request
    should include documentation to substantiate that the proposed
    change does not significantly impact interoperability or global
    seamless operations and any necessary operational limitations and/or
    restrictions. Any change to the data link definitions listed in
    Table‑1 and Table‑1a is considered a change to the provisions of
    this AC, including:

-   Any standard not recognized in this AC

-   Partial compliance to the criteria provided in the rows of Table‑2
    and Table‑2a

-   Deviations from the standards recognized in this AC

-   Deviations from the relevant objectives identified in Annex A of
    RTCA/DO‑264/ED‑78A.

**Table‑2. Criteria for the Aircraft Data Link System**

+--------+--------------+----------------------------------------------+
| **Ai   | Applicable   | **Reference to criteria applicable to        |
| rcraft | Standard     | aircraft means of compliance**               |
| Design |              |                                              |
| ator** |              |                                              |
+--------+--------------+----------------------------------------------+
| ATN B1 | DO-          | Annex A, Allocation of requirements (Denoted |
|        | 290/ED-120,\ | by "Aircraft System")                        |
|        | Chg 1 and    |                                              |
|        | Chg 2        |                                              |
+--------+--------------+----------------------------------------------+
|        | DO-          | Annex B, para. B.2.1, Airborne System CM     |
|        | 280B/ED-110B | P/OICS                                       |
|        |              |                                              |
|        |              | Annex B, para. B.4.1, Airborne System CPDLC  |
|        |              | P/OICS                                       |
+--------+--------------+----------------------------------------------+
|        | Standards    | See Table‑2a for VDL M2.                     |
|        | for          |                                              |
|        | sub-networks |                                              |
+--------+--------------+----------------------------------------------+
| FANS   | D            | Annex B, Allocation of requirements (Denoted |
| 1/A+   | O‑306/ED‑122 | by "Aircraft System)                         |
+--------+--------------+----------------------------------------------+
|        | DO-          | Section 6, Allocation of interoperability    |
|        | 258A/ED-100A | requirements (Denoted by "Air") and relevant |
|        |              | portions.                                    |
+--------+--------------+----------------------------------------------+
|        | DO-          | Annex A, Allocation of requirements (Denoted |
|        | 290/ED-120,\ | by "Aircraft System")                        |
|        | Chg 1 and    |                                              |
|        | Chg 2        |                                              |
+--------+--------------+----------------------------------------------+
|        | D            | Paragraph 4.2.13.2, Downlink Message         |
|        | O‑305/ED‑154 | Elements                                     |
+--------+--------------+----------------------------------------------+
|        | Standards    | See Table‑2a for selected sub-networks.      |
|        | for          |                                              |
|        | s            |                                              |
|        | ub-networks. |                                              |
+--------+--------------+----------------------------------------------+
| FANS   | D            | Annex B, Allocation of requirements (Denoted |
| 1/A    | O‑306/ED‑122 | by "Aircraft System")                        |
+--------+--------------+----------------------------------------------+
|        | D            | Section 6, Allocation of interoperability    |
|        | O-258/ED-100 | requirements (Denoted by "Air").             |
|        |              |                                              |
|        |              | Applicable restrictions:                     |
|        |              |                                              |
|        |              | Oceanic and remote only                      |
+--------+--------------+----------------------------------------------+
|        | Standards    | See Table‑2a for selected sub-networks.      |
|        | for          |                                              |
|        | s            |                                              |
|        | ub-networks. |                                              |
+--------+--------------+----------------------------------------------+
| FANS   | D            | Annex B, Allocation of requirements (Denoted |
| 1/A    | O‑306/ED‑122 | by "Aircraft System"), criteria only for the |
| ADS‑C  |              | "surveillance element," which are supported  |
|        |              | by the IER and PR data link services using   |
|        |              | AFN and ADS‑C functionality.                 |
|        |              |                                              |
|        |              | Applicable restrictions:                     |
|        |              |                                              |
|        |              | Oceanic and remote only, not eligible for    |
|        |              | RCP operations                               |
+--------+--------------+----------------------------------------------+
|        | DO-          | Section 6, Allocation of interoperability    |
|        | 258A/ED-100A | requirements (Denoted by "Air") for AFN and  |
|        |              | ADS‑C functionality only.                    |
+--------+--------------+----------------------------------------------+
|        | Standards    | See Table‑2a for selected sub-networks.      |
|        | for          |                                              |
|        | s            |                                              |
|        | ub-networks. |                                              |
+--------+--------------+----------------------------------------------+
| FMS    | D            | Annex B, Allocation of requirements (Denoted |
| WPR    | O‑306/ED‑122 | by "Aircraft System"), criteria only for the |
|        |              | "surveillance element," which are supported  |
|        |              | by the IER and PR data link services using   |
|        |              | FMS WPR functionality.                       |
|        |              |                                              |
|        |              | Applicable restrictions: Oceanic and remote  |
|        |              | only, not eligible for RCP operations.       |
+--------+--------------+----------------------------------------------+
|        | ARINC 702A   | Paragraph 4.3.6, AOC Function, for automatic |
|        |              | position reports.                            |
|        |              |                                              |
|        |              | *[Note]{.underline}: Provided for definition |
|        |              | of term FMS WPR and interoperability aspects |
|        |              | of the AOC functionality. See DO-306/ED‑122  |
|        |              | for the safety assessment criteria with      |
|        |              | respect to use of this functionality.*       |
+--------+--------------+----------------------------------------------+
|        | Standards    | See Table‑2a for selected sub-networks.      |
|        | for          |                                              |
|        | s            |                                              |
|        | ub-networks. |                                              |
+--------+--------------+----------------------------------------------+
| ACARS  | ED-85        | Refer to appropriate sections for aircraft   |
|        |              | data link system, if selected capability and |
|        |              | use.                                         |
+--------+--------------+----------------------------------------------+
|        | ED-89        | Refer to appropriate sections for aircraft   |
|        |              | data link system, if selected capability and |
|        |              | use.                                         |
+--------+--------------+----------------------------------------------+
|        | ED-109       | Refer to appropriate sections for aircraft   |
|        |              | data link system, if selected capability and |
|        |              | use.                                         |
+--------+--------------+----------------------------------------------+
|        | A623         | Refer to appropriate sections for aircraft   |
|        |              | data link system based on selected           |
|        |              | capabilities and uses.                       |
+--------+--------------+----------------------------------------------+
|        | Standards    | See Table‑2a for selected sub-networks.      |
|        | for          |                                              |
|        | s            |                                              |
|        | ub-networks. |                                              |
+--------+--------------+----------------------------------------------+

**Table‑2a. Criteria for aircraft sub-network interface
(Interoperability)**

+------------------+---------------------------------------------------+
| Sub-network      | Reference to criteria applicable to aircraft      |
| designator       | means of compliance                               |
+------------------+---------------------------------------------------+
| VDL M0/A         | A618-6 for air/ground protocol                    |
+------------------+---------------------------------------------------+
| VDL M2           | a)  TSO-C160, additionally, for Class V and Class |
|                  |     W (non-8208 compliant installations),         |
|                  |     applicants should submit the performance      |
|                  |     standards that are used to qualify the        |
|                  |     sub-network access protocol (SNAcP)           |
|                  |     sub-layer.                                    |
|                  |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | z)  A631-5                                        |
+------------------+---------------------------------------------------+
| HFDL             | a)  TSO-C158                                      |
|                  |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | a)  A753-3                                        |
+------------------+---------------------------------------------------+
| SATCOM           | a)  TSO-C132                                      |
| (Inmarsat)       |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | b)  A741P2-7                                      |
+------------------+---------------------------------------------------+
| SATCOM (Iridium) | a)  DO-262A (MOPS)                                |
|                  |                                                   |
|                  | ```{=html}                                        |
|                  | <!-- -->                                          |
|                  | ```                                               |
|                  | c)  A741                                          |
|                  |                                                   |
|                  | d)  A761-2                                        |
+------------------+---------------------------------------------------+

**ADDITIONAL ACRONYMS for Table‑2 and Table‑2a:**

  -------------------- --------------------------------------------------
  AOC                  Aeronautical operational control

  IER                  Information exchange and reporting

  P/OICS               Protocol/operational implementation conformance
                       statement

  PR                   Position reporting

  SATCOM               Satellite communications

  VDL M0/A             VHF data link mode 0/A
  -------------------- --------------------------------------------------

# 6. Design Considerations for Aircraft Data Link Systems.  {#design-considerations-for-aircraft-data-link-systems. .Style-Heading-1 .unnumbered}

The following design considerations provide criteria that are additional
to the criteria provided in Section 4 of this AC, in particular, Table‑2
and Table‑2a and Section 5 and 6 of DO‑264/ED‑78A.

a.  **Flight deck human-machine compatibility.**

    1.  Consider other integrated systems when incorporating an aircraft
        data link system on the flight deck. Also take into account the
        existing flight deck philosophy for the aircraft type design and
        the airspace operating environment.

    2.  Make the human-machine interface compatible with the crew
        interface and flight deck design of the particular aircraft in
        which the aircraft data link system is installed.

    3.  If multiple ATS data link applications and sub-networks are
        available to the aircraft, base the crew interface and related
        crew procedures on a common and compatible flight deck
        philosophy.

b.  **Flight deck human machine interface.**

    1.  Flight Deck Annunciation. The aircraft data link system should
        have the following annunciation capabilities integrated into the
        flight deck:

\(a\) Unless otherwise substantiated by the safety assessment, an aural
and visual indication for each uplink ATS message intended to be
displayed to the flight crew. Include messages not being displayed
immediately because of lack of crew acknowledgement to an earlier ATS
message. Visual alerts alone can be used for uplink non‑ATS messages.

\(b\) Indication to the flight crew of aircraft data link system
failure.

\(c\) Indication of status to the flight crew of the air/ground data
communication sub-network such as loss of an air/ground link that would
cause the aircraft data link capability to no longer meet the
requirements for the intended function.

\(d\) If message storage or printing capability is provided, include an
advisory alert should be given, to the flight crew, when storage or
printing is not possible.

\(e\) Aural annunciations indicating the receipt of a data
communications message during critical flight phases (e.g., takeoff and
landing) should be suspended until after the critical flight phase. The
criteria that defines critical flight phases should be consistent with
the particular flight deck philosophy.

2.  Flight Deck Controls. Aircraft data link systems should meet the
    following control capability criteria:

\(a\) Provide a way for the flight crew to activate or deactivate each
of the cockpit data communication applications and sub-networks.

\(b\) Provide a way for the flight crew to identify, in real time, the
identity of the ATS provider(s) connecting to the aircraft, and the
applications and sub-networks involved with each connection.

\(c\) Provide a way for the flight crew to acknowledge receipt of CPDLC
messages to the sender, when required.

\(d\) Provide a way for the flight crew to list, select, and retrieve
the most recent CPDLC messages received and sent by the flight crew.
Indication of the status of each message, the time it was sent by the
originator.

\(e\) Provide a way for the flight crew to clear CPDLC messages from the
display. However, protect this capability against inadvertent clearing.

\(f\) Provide a way for the flight crew to create, store, retrieve,
edit, delete, and send messages.

\(g\) If a direct interface exists between the flight deck aircraft data
link system and other computer functions, (such as flight planning and
navigation), provide a way for the flight crew to preview any changes to
the flight plan prior to activation or execution. The mechanism to
respond to the CPDLC message should be different than the mechanism used
to activate the flight plan in the aircrafts flight management system.

3.  Flight Deck Displays. Flight deck displays should meet the following
    criteria:

\(a\) Display CPDLC messages, using message elements defined in the
standards identified in Table‑1, without being truncated. If multiple
pages are used to display messages, the crew should have clear
indication. Use a format that the flight crew can comprehend without the
need for translation from English into another language.

\(b\) Display the CPDLC messages so the flight crew can read them
without leaving their seats.

\(c\) Display CPDLC messages until acknowledged, unless the flight crew
selects another message, or in the case of a multi-function display,
another display format or function is selected. In these cases include a
visual reminder that indicates that pending messages are waiting for a
response.

\(d\) Display CPDLC messages so that messages are distinguishable from
each other. Display the status of each message, if acknowledged or not,
together with the message.

\(e\) When the aircraft data link system is sharing a display with other
aircraft functions, ensure appropriate priority for the information to
be displayed.

\(f\) If a message is greater than the available display area and only
part of the message is displayed, provide a visual indication to the
pilot to indicate the presence of the message remainder.

c.  **Flight Deck Printer.** You can use a flight deck printer for
    storing data communications messages received or sent during the
    current flight. Ensure it satisfies integrity and interface design
    criteria appropriate with the aircraft flight deck philosophy.

d.  **Data Communication Recording.** For those aircraft required to
    install data communication recording equipment in accordance with
    CFR part ?, §?, effective month day year, AC 20-160, *Onboard
    Recording of Controller-Pilot Data Link communication in Crash
    Survivable Memory*, describes acceptable means of compliance.

    **7. Ground and Flight Test Evaluation**.

Test your aircraft data link system and application by end-to-end ground
testing that verifies system interoperability and performance, per
section 6 of DO-264/ED-78A. Test with either an appropriate ATS unit or
with test equipment that is representative of an actual ATS unit and
air-ground and ground-ground networks. Submit evidence that demonstrates
compliance with the safety, performance and interoperability
requirements appropriate for the aircraft data link system per Table‑1
and Table‑1a.

**8. Airplane/Rotorcraft Flight Manual (A/RFM) and A/RFM Supplement
Wording**.

Provide a description of all normal and submodes of aircraft data link
system operation including what actions are expected by the flight crew
for each case. You can reduce the material addressed by the A/RFM or
A/RFM supplement if the information is included in other related
references, such as a flight crew operating manual that is used by the
operator as the basis for flight crew qualification. See AC 120-70B, for
guidance.

a.  **Operating Limitations**.

```{=html}
<!-- -->
```
(1) Use operating limitations to control the use of data link
    applications that are intended for evaluation in operational service
    or if an operating limitation provides an alternative to satisfying
    the criteria contained in this AC.

(2) Operating limitations are not necessary provided the aircraft data
    link system has been shown to operate in accordance with the
    criteria provided in Table‑1 and Table‑1a.

```{=html}
<!-- -->
```
b.  **Operating Procedures**. Assure the operating procedures in the
    A/RFM or A/RFM supplement are consistent with and refer to the
    safety, performance and interoperability requirements that were used
    to demonstrate the system. For example:

> "*The FAA has approved the aircraft data link system to the criteria
> contained in AC 20-140A. This approval was based on the standards for
> (insert appropriate aircraft designators from Table‑2, e.g., FANS 1/A,
> ATN B1, etc., and sub-network designators from Table‑2a. Also, if the
> FAA approves variations to the criteria and those variations impact
> operational use of the data link system, include additional
> information that describes the operational impact either by reference
> to the applicant's document or as part of the A/RFM). This design
> approval does not constitute operational authorization. See AC 120-70B
> for operational authorization*."

Dave W. Hempe

Manager, Aircraft Engineering Division

Aircraft Certification Service

**Appendix 1. Related Documents**.

1.  **International Civil Aviation Organization (ICAO) documents:**

    a.  Annex 2, *Rules of the Air*.

    b.  Annex 6, *Operation of Aircraft*.

    c.  Annex 10, *Aeronautical Telecommunications*.

    d.  Annex 11, *Air Traffic Services*.

    e.  Doc 4444, *Air Traffic Management*.

    f.  Doc 9869, *Manual on Required Communication Performance (RCP)*.

2.  **RTCA, Inc. Documents (RTCA/DO) and European Organization for Civil
    Aviation Equipment (EUROCAE) documents (ED):**

    a.  RTCA DO-160E, *Environmental Conditions and Test Procedures for
        Airborne Equipment*, dated December 9, 2004.

    b.  RTCA DO‑178B/EUROCAE ED-12B, *Software Considerations in
        Airborne Systems and Equipment Certification*, dated December 1,
        1992.

    c.  RTCA DO‑224, Signa-in-Space Minimum Aviation System Performance
        Standards (MASPS) for advanced VHF Digital Data Communications
        Including Compatibility with Digital Voice Techniques.

    d.  RTCA DO-254, *Design Assurance Guidance For Airborne Electronic
        Hardware*, dated April 19, 2000.

    e.  RTCA DO-258A/EUROCAE ED-100A, *Interoperability Requirements for
        ATS Applications Using ARINC 622 Data Communications*, dated
        April 7, 2005.

    f.  RTCA DO‑262A, Minimum operational Performance Standrards for
        Avionics Supporting Next Generation Satellite Systems (NGSS).

    g.  RTCA DO-264/EUROCAE ED-78A, *Guidelines for Approval of the
        Provision and Use of Air Traffic Services Supported by Data
        Communications*, dated December 14, 2000.

    h.  RTCA DO‑265, Minimum Operational Performance Standards for
        Aeronautical Mobile High Frequency Data Link (HFDL).

    i.  RTCA DO‑270A, Minimum Aviation System Performance Standards
        (MASPS) for Flight Information Services-Broadcast (FIS-B) Data
        Link.

    j.  RTCA DO-280B/EUROCAE ED-110B, *Interoperability Requirements
        Standard for ATN Baseline1 (INTEROP ATN B1)*, dated June 26,
        2007.

    k.  RTCA DO-290 Changes 1 and 2/EUROCAE ED-120 Changes 1 and 2,
        *Safety and Performance Requirements Standard for Air Traffic
        Data Link Services in Continental Airspace (Continental SPR
        Standard)*, dated April 29, 2004.

    l.  RTCA DO-305/EUROCAE ED-154, *Future Air Navigation System 1/A
        (FANS 1/A) -- Aeronautical Telecommunications Network (ATN)
        Interoperability Standard*, dated June 26, 2007.

    m.  RTCA DO-306/EUROCAE ED-122, *Safety and Performance Standard for
        Air Traffic Data Link Services in Oceanic and Remote Airspace
        (Oceanic SPR Standard)*, dated October 11, 2007.

    n.  EUROCAE ED‑85, *Data-Link Application System Document (DLASD)
        for the 'Departure Clearance' Data-Link Service*..

    o.  EUROCAE ED‑89, *Data-Link Application System Document (DLASD)
        for the 'ATIS' Data-Link Service*.

    p.  EUROCAE ED‑93, *Minimum Aviation System Performance Standard for
        CNS/ATM Message Recording Systems*, dated November 23, 1998.

    q.  EUROCAE ED‑106, *Data-Link Application System Document (DLASD)
        for the 'Oceanic Clearance' Data-Link Service*..

3.  **ARINC documents**

```{=html}
<!-- -->
```
a.  A618-6, Air/Ground Character-Oriented Protocol Specification, dated
    June 16, 2006

```{=html}
<!-- -->
```
e.  A631-5, VHF Digital Link (VDL) Mode 2 Implementation Provisions,
    dated December 3, 2008

f.  A753-3, HF Data Link System, dated February 16, 2001

g.  A741P2-9, Aviation Satellite Communication System, Part 2, System
    Design and Equipment Functional Description, dated November 22, 2006

h.  A761-3, Second Generation Aviation Satellite Communication System,
    Aircraft Installation Provisions, dated November 22, 2006

```{=html}
<!-- -->
```
4.  **Federal Aviation Administration (FAA) documents:**

    a.  AC 20-115B, *RTCA, Inc., Document RTCA/DO-178B*.

    b.  AC 20-152, *RTCA, Inc., Document RTCA/DO-254, Design Assurance
        Guidance for Airborne Electronic Hardware*.

    c.  AC 20‑160, *Onboard Recording of Controller-Pilot Data Link
        Communication in Crash Survivable Memory.*

    d.  AC 21-16E, *RTCA, Inc., Document RTCA/DO-160, Environmental
        Conditions and Test Procedures for Airborne Equipment*.

    e.  AC 120-70B, *Operational Authorization Process for use of Data
        Link Communication System.*

    f.  TSO C132, (Satcom Inmarsat)

    g.  TSO C158, Aeronautical Mobile High Frequency Data Link (HFDL)
        Equipment.

    h.  TSO C160, (VDL M2)

    i.  TSO C177, Data Link Recorder Systems