NATCA Bookshelf

National Office Week in Review: August 17, 2016

A publication of the National Air Traffic Controllers Association

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Page 15 of 18

The Distance Measuring Equipment (DME) infrastructure is most suited to provide a backup to GNSS because most a ir carrier aircraft are equipped and significant infrastructure already exists. DME was not originally designed to provide RNAV, but over the years, avionics manufacturers have integrated scanning DME receivers with their Flight Management Systems (FMS) to provide positioning suitable for RNAV. The current DME network has significant RNAV coverage gaps in Class A and terminal airspace over Continental United States (CONUS), which restricts DME RNAV to aircraft that also carry Ine rti al Reference Unit (IRU). Approximately 70 percent of air carrier operators carry DME RNAV and I RU equipment. The remaining 30 percent carry DME RNAV avionics without IRU and are therefore not a pproved to fly RNAV procedures. The inability of those DME RNAV without IRU to fly RNAV procedures is a significant shortfall that the NG DME p rogram intends to close. This shortfall exists today but the impacts are manageable because En Route and Terminal operations are largely based on airways defined by Very High Frequency Omni - Directional Range (VOR) and conventional instrument flight procedures, which can be flown by aircraft equipped with either VOR or GNSS equipment. As the VORs and conventional routes and procedures are removed, a GNSS disruption could render, a pproximately 30 percent of the air carrier unable to continue flying the PBN procedures because a resilient PBN - capable RNAV alternative is not available at all areas where it is needed. Those aircraft will transition to less accurate conventional navigation using the VOR Minimum Operational Network (MON) and aircraft separation using radar vectors which could increase workl oad for pilots and controllers. In high air traffic areas, these events may cause disruptions to traffic flow resulting in delays and diverts for passengers an d cargo delivery which may also ripple through the air traffic system causing additional pilot and controller workload increases and delays. RNAV and PERFORMANCE BASED NAVIGATION (PBN): Bennie Hutto (PCT) is the Article 48 Representative for RNAV and PBN criteria work. Mr. Hutto's report for the membership is below : RNAV ATS Routes The current "Lateral Protected Airspace Criteria for RNAV ATS Routes" as contained within FAA 7400.2K states the "basic width of an RNAV route is 8 NM (4 NM on each s ide of the route centerline)." The FAA 7400.2K al so discusses "Width Reductions" in which "a reduced width is permissible to obtain additional traffic capacity and flexibility through the use of multiple routes and to avoid encroachment on special use airspace or oth er essential maneuvering areas." We are in the process of working with AJV - 14 and AFS - 400 to have the criteria amended regarding "RNAV Width Routes" with the standard being 3 NM instead of the 4 NM, especially since the accuracy requirements for RNAV 2 air craft is 2 NM, 95 percent of the flight and if that accuracy can't be met, then those aircraft are not eligible to fly an RNAV ATS Route and would require radar vectors or assigned a conventional route. Pilot Controller Procedures & Systems Integration (PC PSI) A meeting was held in Boston on August 15th, in which the following topics were discussed: Top Altitude and Climb Maintain C learances – At the Aeronautical Charting Forum (ACF), NATCA raised concerns that the way "Top Altitude " is referenced within t he FAA 7110.65 and AIM has now made every SID a Climb Via procedure, which was never the intention. A recommendation has been made to change language within these documents, therefore allowing "Maintain" or "Climb and Maintain" clearances to be

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