**THE TWENTY-FIFTH MEETING OF THE**

**INFORMAL PACIFIC ATC CO-ORDINATING GROUP**

**(IPACG/25)**

(Tokyo, Japan, 24-27 October 2006)

**Agenda Item 3:** Report on relevant outcomes from other meetings

**Automatic Dependent Surveillance In-Trail Climb/Descent Procedure in
the Ocean**

(Presented by the Federal Aviation Administration)

**[SUMMARY]{.underline}**

The Federal Aviation Administration (FAA) and others are in the early
stages of evaluating concepts for In-Trail Climb/Descent Procedures
(ITP) in oceanic airspace using existing Automatic Dependent
Surveillance-Contract (ADS-C) capabilities. FAA is exploring options for
ADS-C ITP; however, by using work accomplished by others, FAA may be
able to expedite determination of whether ADS-C ITP is viable in the
oceanic environment.

**1. Background**

1.  At an Action Plan 22: NAM/EUR Interoperability Trials (AP22) meeting
    in Glasgow, Scotland, during the week of 11-15 September 2006,
    representatives from the FAA, Eurocontrol and other organizations
    met to discuss Automatic Dependent Surveillance-Contract (ADS-C) and
    ADS-Broadcast (ADS-B) In-Trail Climb/Descent Procedures (ITP). FAA
    has presented information on an ITP concept for the ocean at
    previous oceanic work group meetings.

**2. Discussion**

1.  FAA is in the very early stages of pursuing ADS-C ITP in oceanic
    airspace. Attachment A describes current FAA concepts for ADS-C ITP.

2.  Although FAA supports ADS-C ITP, FAA may not be able to devote
    adequate resources toward quick development of ITP due to higher
    priority oceanic separation reduction efforts. FAA has been advised
    that the United Kingdom (U.K.) is undertaking an analysis for
    possible reductions to time-based longitudinal separation between
    ADS-C equipped aircraft. Additionally, during the recent and
    on-going Oceanic Tailored Arrival trial in Oakland Center (ZOA),
    NASA Ames noticed opportunities in oceanic airspace where an ADS-C
    ITP may have provided benefits.  Hopefully, data collected by the
    U.K. and NASA Ames may help further develop the ADS-C ITP.

3.  Furthermore, we understand the Separation and Airspace Safety Panel
    (SASP) will be evaluating changes to the PANS ATM that relate to
    Global Navigation Satellite System (GNSS) references replacing
    current references to ground-based NAVAIDs.  By using work
    accomplished by others, FAA may be able to expedite determination of
    whether ADS-C ITP is viable in the oceanic environment.

**3. Recommendation**

3.1 The meeting is invited to:

a.  Take note of the information presented; and

b.  Keep FAA apprised of other work that may be on-going concerning
    ADS-C enabled oceanic procedures.

**-- END --**

> **ATTACHMENT A**
>
> **ADS-C Oceanic In-Trail Climb/Descent Procedure (ITP)**
>
> **Jointly Prepared by CAASD & FAA ATO-E**
>
> **Introduction**

-   **FAA in early stages of evaluating concept for Oceanic In-Trail
    Climb/Descent Procedure**

    -   Climb/descent to Requested Flight Level through one intermediate
        FL occupied by a blocking aircraft

    -   Based on ADS-C reports & new ATC procedures

    -   Builds on domestic DME rules in ICAO Doc. 4444, paragraph
        5.4.2.3.2.3 & FAAO 7110.65, 6-4-2, c.1

    -   Incorporate lessons learned from TCAS ITP, ADS-B ITP

-   **This briefing presents initial analysis**

    -   Need to refine & validate, identify issues

    -   Work in progress

-   **Customer Benefits**

    -   More opportunities to reach optimal altitudes

    -   Ability to climb to avoid turbulence

    -   Potential to maximize revenue payload

    -   Maximize on-board equipment use

> **Proposed Operational Concept**

-   ADS-C ITP is a procedure that can be requested by the pilot or
    controller-initiated

-   Controller responsible for ensuring separation with all aircraft
    (assisted by Ocean21 conflict probe & tools)

-   ADS-C ITP will have smaller longitudinal separation minima (*xx* nm)
    than standard rules (e.g., 30 NM, 50 NM) with aircraft at
    intermediate flight levels

-   Pacific Trials First (currently using 30 or 50nm separation)

-   Atlantic Trials Second (various standards in use)

> **Procedure may have near and long-term versions**

-   Goal is for early benefits without Ocean21 changes

    -   Controller workload implications & some limitations

-   Explore additional user benefits & reduced controller workload if
    Ocean21 is enhanced to automate procedure

> **ADS-C ITP Cases**
>
> **ADS-C ITP Concept Overview**

+-----------------------------------------------+----------------------+
| > Preconditions                               |                      |
+-----------------------------------------------+----------------------+
| > *xx* nm longitudinal separation minima      | > Doc 4444,          |
| > while vertical separation is lost           | > 5.4.2.3.2.3        |
+-----------------------------------------------+----------------------+
| > Direct controller pilot communication       | > Doc 4444,          |
|                                               | > 5.4.2.3.1          |
+-----------------------------------------------+----------------------+
| > One aircraft maintains level (blocking      | > Doc 4444,          |
| > aircraft)                                   | > 5.4.2.3.2.3 (b)    |
+-----------------------------------------------+----------------------+
| > Same track                                  | > Doc 4444,          |
|                                               | > 5.4.2.3.2.3        |
+-----------------------------------------------+----------------------+
| > Simultaneous position reports (issue)       | > Doc 4444,          |
|                                               | > 5.4.2.3.2.3 (c)    |
+-----------------------------------------------+----------------------+
| > xx nm longitudinal separation minima while  | > Doc 4444,          |
| > vertical separation is lost                 | > 5.4.2.3.2.3        |
+-----------------------------------------------+----------------------+
| > Direct controller pilot communication       | > Doc 4444,          |
|                                               | > 5.4.2.3.1          |
+-----------------------------------------------+----------------------+
| > One aircraft maintains level (blocking      | > Doc 4444,          |
| > aircraft)                                   | > 5.4.2.3.2.3 (b)    |
+-----------------------------------------------+----------------------+
| > Same track                                  | > Doc 4444,          |
|                                               | > 5.4.2.3.2.3        |
+-----------------------------------------------+----------------------+
| > Simultaneous position reports (issue)       | > Doc 4444,          |
|                                               | > 5.4.2.3.2.3 (c)    |
+-----------------------------------------------+----------------------+

> **ADS-C ITP Concept Timeline**
>
> **Analysis Issues**

-   **Additional analysis needed to determine performance criteria &
    procedural steps, such as**

    -   Definition of simultaneous reports

    -   Maximum time from granting clearance to aircraft reestablishing
        vertical separation

    -   Guidelines for maximum converging speed & initial separation
        distance (similar to TCAS ITP conditions)

    -   Initial separation distance from Ocean21 displays

-   **Hazard analysis and safety assessment (collision risk) needed**

> **Business Case**

-   **Benefits Analysis**

    -   Estimate Oceanic Benefits

        -   ZOA, ZAN & ZNY

-   **FAA Cost (ROM) for Implementation**

-   **Complete Concept Analysis**

    -   Performance criteria

        -   Ocean21 Performance

        -   Communications system performance

    -   Procedural steps

        -   Definition of simultaneous reports

        -   Max time from granting clearance to aircraft re-establishing
            separation

        -   Guidelines for maximum convergence speed & initial
            separation distance

        -   Initial separation distance

    -   Controller Workload Preliminary Assessment

    -   Preliminary Hazard Analysis & Safety Assessment

    -   Pilot Situational Awareness requirements

    -   Pilot Procedures

-   **Go / No Go Decision**

> **Implementation Activities**

-   **Resolve Datalink Performance Issues**

-   **ATOP/ Ocean 21 NCPs**

    -   Not anticipated for initial implementation

-   **Separation Reduction Approval**

    -   **Pacific**

        -   APANPIRG, ISPACG, IPACG, OWG, FIT

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    -   **Atlantic**

        -   NAT SPG, IMG, ATMG, SARSIG, FIG

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    -   **ICAO**

        -   SASP

    -   **FAA**

        -   OSRWG, AOV

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-   **AT Implementation**

    -   Manuals

    -   Procedures

    -   Training

    -   LMR

-   **Pilot Procedures / Situational Awareness**

-   **Hazard Analysis & Safety Assessment**

    -   Collision Risk Model

> **ADS-C ITP Concept Summary**

-   **Preliminary conclusion: ADS-C ITP is feasible**

-   **Resources should be allocated to begin next steps**

-   **Next steps**

    -   Complete concept analysis, issues & initial procedure

    -   Estimate controller workload effect on ADS-C ITP

    -   Estimate oceanic benefits in ZOA, ZAN & ZNY

    -   Safety assessment & hazard analysis

    -   ICAO approval

    -   Develop plan for ADS-C ITP implementation