Ascend Though Innovation (ATISpace/ATI) Support to the DME Program

 

ATI is providing system engineering, analysis and support to evaluate the Distance Measuring Equipment (DME) infrastructure.  We evaluate DME coverage gaps, provide frequency assignment modeling and associated engineering processes, and support the proposed DME gap filling by the Navigation Services Program Office. 

The FAA NextGen vision is the enhancement of space-based communication, navigation, and surveillance instead of the existing ground-based infrastructure.  The DME network system provides positioning service for some Performance Based Navigation (PBN) operations. Aircraft equipped with suitable RNAV avionics, such as most air carrier, regional, and business aircraft, use multiple DMEs to calculate their positions for RNAV operations. 

Sustaining the current inventory of DMEs is necessary to support PBN operations.  Therefore, efforts are progressing under the NextGen Navigation Initiatives project to expand the specified service volume for DME, which enables increased DME protected signal coverage in the terminal airspace.    Currently, the specified DME service volume has significantly less coverage volume than the actual performance of the DME signals.  Expanded Service Volume requests are used on a case-by-case basis to expand DME Standard Service Volume where additional coverage is needed to enable PBN procedures. 

This effort also serves to minimize the need for building new DME sites to fill any coverage gaps that may persist within the NAS.  Assessing whether the NAS needs new DME sites for NextGen first requires identifying where coverage gaps exist relative to the current DME-DME network.

ATI is tasked to identify and document DME gaps to evaluate and re-engineer the coverage for the proposed filler DMEs.  We are identifying DME gap sites candidate locations and providing the engineering analysis of Enroute DME loading and interrogation capacities by site.  This task also includes analysis of DME support for the alternative 5 terminal airports and unique study support to identify DME inter-dependencies.

We initially researched about all aircraft types, what type of Flight Management Systems (FMS) are used and how many DMEs are installed in the aircraft.  After starting coverage analysis with RNAV-Pro, we presented preliminary Frequency assignment protocols for new sites and presented coverage risk associated to Military and Canadian sites as part of PBN solution.  We then reviewed necessary algorithm modifications of PDARs extraction code to identify aircraft equipage.    

ATI is an experienced user of iRCAS and uses it to create coverage for DME sites. We completed iRCAS runs for the new sites and missing TAP run sites.  We created a list of the locations and plotted new DME sites around 62 airports on the Google Earth.   During this effort, we found discrepancies for DME sites between AFM and FOMS data base.          

ATI completed the RNAV-Pro terminal area coverage cases for PBN Initial and End-State at 1,500-ft and 5,000-ft AGL.  We wrote the RNAV-Pro terminal area coverage and Traffic-Loaded DME RMLS Query SOP and ran the RNAV-Pro Enroute cells for Initial and End States at FL180 and FL240. ATI is identifying ways to automate RNAV-Pro process so that the analysis can be performed at a faster pace, using cloud computing tools and some open source testing frameworks.

We developed a process and wrote java code to streamline the CSV Data output from RNAV pro to make it easier to import into analysis tools such as Matlab. We also developed a process using Microsoft Access for merging the PBN List with the CONUS Enroute 405 terminal solution set from Mitre that can quickly identify changes in the list when we receive updates from Mitre.

ATI is also responsible for revised PBN DME service volume definitions for the 9840.1 Order by integrating Technical Working Group comments to the definitions.