**THE TWENTY-SIXTH MEETING OF THE**

**INFORMAL PACIFIC ATC CO-ORDINATING GROUP**

**(IPACG/26)**

(Anchorage, Alaska, USA, May 14-18, 2007)

**Agenda Item 6**: Air Traffic Management (ATM) Issues

**Use of 30 NM Lateral / 30 NM Longitudinal Separation (30/30)**

(Presented by the Federal Aviation Administration)

**[SUMMARY]{.underline}**

This information paper provides a status update on the use of 30 NM
lateral / 30 NM longitudinal separation (30/30) in the Oakland Oceanic
FIR.

**1. Background**

1.  Oakland ARTCC (ZOA) introduced the 30/30 separation standard on a
    trial basis in Oceanic Control Sector 3 (OC3) in December 2006.

2.  As part of the trial, the FAA established a Scrutiny Group to
    evaluate the OC3 30/30 operational trial. The 30/30 Scrutiny Group
    was tasked to examine data from the operational trial and data link
    communications within the entire Oakland Oceanic Flight Information
    Region, (FIR).

3.  The initial findings of the 30/30 Scrutiny Group indicated that the
    initial trials were a success with one exception. The exception was
    the reliability of the Perth Ground Earth Station (GES) which had
    suffered several outages over the course of the 30/30 trials.

4.  Based on these findings, the FAA began work to expand the use of
    30/30 to the rest of the Oakland FIR. A target date of March 13,
    2007 was established with the caveat that performance of the Perth
    GES would be closely monitored and must improve.

[]{.mark}

**2. Discussion**

1.  The FAA's 30/30 Scrutiny Group continued to evaluate the 30/30
    trials in OC3 and the overall data-link performance within the FIR.

2.  During February 2007, the Perth GES again suffered from outages. The
    FAA consulted directly with SITA on the causal factors for these
    outages and any planned remedies. SITA advised the FAA that one of
    the causal factors was still undetermined and another identified but
    would not be corrected until the 2^nd^ quarter of calendar year 07.

3.  Based on this information and the knowledge that the Perth GES was
    still subject to outages due to known and unknown problems, the FAA
    made the determination to expand the 30/30 trials on the planned
    date of March 13, 2007 but with a different operational concept.

4.  In the interest of safety, the FAA decided to restrict the use of
    Automatic Dependant Surveillance, (ADS), based separation (30/30 and
    50NM longitudinal). ADS-based separation will only be authorized
    when climbing/descending through the altitude of another aircraft
    and/or when opposite direction traffic has passed each other and the
    appropriate distance has been achieved.

5.  In making this determination, the FAA looked at several scenarios,
    from terminating the 30/30 trials to disallowing the use of the
    Perth GES for data-link. The restricted approach was seen to provide
    the best opportunity to continue to use ADS based separation while
    maintaining safety of flight within the Oakland FIR.

6.  The FAA will continue to work closely with SITA and monitor the
    progress of the planned upgrades to the Perth GES. Once the upgrades
    are completed, the FAA will re-evaluate its position on the
    restricted use of ADS-C based separation in the Oakland FIR

7.  The FAA has already begun collecting data to support the use of ADS
    based separation in the Anchorage FIR. It is too soon to speculate
    as to when the analysis will be completed, but this is a high
    priority for the FAA.

3\. Current Status

1.  On May 1-3, the FAA's 30/30 Scrutiny Group met. During this meeting
    all aspects of the 30/30 trials in the Oakland FIR were reviewed
    including the work by SITA on the Perth GES.

3.2 On April 18, SITA successfully made the last planned CY07 upgrade to
the Perth GES. This action corrected all of the known problems with the
Perth GES that caused the FAA to restrict the use of reduced separation
standards that rely on Data-link services (CPDLC/ADS-C).

3.3 The transit times for Data-link messages for recent months have been
in conformance with the FOM as well.

3.4 Based on this information, the FAA 30/30 Scrutiny Group has
recommended that the current restrictions be cancelled. The FAA's
Oceanic Separation Reduction Working Group (OSRWG) has concurred with
this recommendation.

3.5 Oakland ARTCC has been given approval to remove the previously
imposed restrictions. Oakland ARTCC is now in the process of determining
a date for this to occur.

**4 Recommendation**

4.1 The meeting is invited to note the information presented in this
paper.

**- END -**