Ascend Through Innovation (ATISpace/ATI) Support to the VOR MON Program

ATI has received recognition from the FAA for providing system engineering, analysis, and support to evaluate and re-engineer the Very High Frequency Omni-Directional Range (VOR) Frequency Protected Service Volume (FPSV) of the Minimum Operational Network (MON).  

The FAA sustains a network of 967 VHF Omnidirectional Range (VOR) navigational aids that do not support Performance-Based Navigation (PBN), which is an integral part of NextGen. Most VOR systems owned by the FAA are over thirty years into their planned 20-year equipment service life.

The Very High Frequency Omni-Directional Range (VOR) Program plans to reduce the number of VOR’s in the National Airspace System (NAS) by approximately 30%.  This reduction is in support of the transition to a more efficient Performance Based Navigation (PBN) routing structure that is consistent with Next Generation Air Transportation System (NextGen) goals and the NAS Efficient Streamlined Services Initiative (NESS).  The retained VORs primarily serve for enabling pilots to revert from PBN to conventional navigation in the event of a Global Positioning System (GPS) outage.

In the current operational environment, the VOR Frequency Protected Service Volume (FPSV) is dependent on the type of equipment used and the intended operation that it is to support. As the number of VORs is reduced in the NAS, the FPSV has to be suitably modified to ensure sufficient VOR coverage for all users.

ATI is evaluating and re-engineering the service volume for the new parameters and criteria proposed, while providing testing, validation and documentation of the resulting engineering analysis and test results.  We are updating protection criteria and frequency assignment modeling and associated engineering processes and providing limits of coverage analysis and interference requirements evaluation for co-channel and adjacent channels. 

Supporting the proposed VOR changes by the Navigation Services Program Office, ATI is updating FAA Order 6050.32 and FAA Order 9840.1, the safety risk management decision process, and enhancing the current spectrum automated systems to apply the relaxed criteria when engineering VORs.  This includes providing the redesign and implementation of existing automation tools and newly developed tools and associated models and integration into the production spectrum systems.

Recently ATI prepared a presentation and whitepaper for First Adjacent-Channel VOR/GBAS Test and are continuing VOR/GBAS first adjacent channel analysis.   In the initial VOR/GBAS adjacent channel flight test in Atlantic City, ATI performed adjacent channel runs and space loss calculator runs to verify data.   We discovered additional co-channels and 2nd adjacent channel interferer during test. We are now conducting the 4th adjacent VOR/VOR Interference Test.

ATI recommended establishing 70NM versus 77NM at 5,000 to 18,000-ft AGL, and no changes to the enroute coverages above FL180.  We updated and delivered 70NM FPSV diagrams for the modified Low and High facilities under the VOR MON implementation.  

We revised the VOR co-channel flight test report to include new Morse code plots during RFI testing and processed and archived the last set of VOR orbit data for VOR MON parametric analysis for the new VOR service volume.  We also presented VOR FPSV parametric analysis to the VOR MON Technical Interchange Meeting.  

We provided spectrum engineering inputs/comments to the 9840.1 Order Revision Board for the new service volumes, and then revised the VOR MON service volume definitions for FAA Order 9840.1 per Technical Working Group comments.  ATI has started building the functions in the existing AFM to incorporate the requirements for VOR MON.