The phase-down is planned to begin in 2008 based on projected Satnav program milestones and anticipated user equipage rates.
The specific Navaids that would no longer qualify for Federal support, at each step of the phase-down, would be determined based on specific criteria, currently under development. Navaids supporting en route procedures would be decommissioned. Navaids supporting terminal procedures could be decommissioned or transitioned to a non-Federal sponsor.
The discontinuance criteria would be published as early as possible and well ahead of the phase-down. A site-specific list of Navaids fitting the discontinuance criteria would be published later-perhaps at the time of WAAS FOC. The advanced site-specific notice would afford users the opportunity to plan their transition to Satnav based upon the operational schedule for the specific Navaids they use most often.
[和訳例]
Phase-downは、計画されたSatnavプログラムのマイルストンと予想されるユーザーの装備率に基づいて、2008年の初めから計画されている。
フェーズダウンの各ステップで、連邦から資格認定されなくなった特定のNavaidsは、現在開発中の特定の判断基準に基づいて決定される。En Route手順を支援するNavaidsは、廃止される。Terminal手順を支援するNavaidsは、恐らく廃止されるか、非連邦スポンサーへ移行される。
廃止の判断基準は、出来るだけ早く出版され、phase-downよりも十分に先行して決定される。サイト特有の廃止の判断基準は、遅れて出版される。多分、WAAS FOCの時期。先進のサイト特有の掲示は、ユーザーに、現在もっともよく使っている特定のNavaidsに対して、運用スケジュールに基づいたSatnavへの移行計画を立案する機会を与える。
・ Phase I - Many currently under-utilized VORs and ILSs would be discontinued at the first step of the phase-down. Preliminary analysis indicates that approximately 350 VORs and 300 ILSs would no longer qualify for Federal support at this first step. ( The population of NDBs would remain essentially intact to support ILS approaches.) Although this represents an approximate 30 percent reduction in the number of Navaids, it would be expected to cause a relatively minor impact on the NAS.
・ Phase II - The second step, planned to occur in 2011, would further reduce the population of ground-based Navaids to the level of the proposed Minimum Operational Network. The Phase II Navaids are intended to support continued operation in the NAS by those aircraft not yet equipped with Satnav avionics, albeit at a reduced level of efficiency.
