Page 16 - Jan25

FROM THE TRAINING CENTER
What Is This MON Thing Anyway?
With the VOR minimum operational network as a backup, basic conventional navigation will be possible if GPS fails
bFy Pete Marx
or many King Air pilots, most of our flying
utilizes the Global Positioning System. What would happen if the entire National Airspace System (NAS) relied solely on GPS and the
system broke down due to technical issues or nefarious intent?
GPS is susceptible to interference, jamming, spoofing or solar events, any of which can disrupt aircraft navigation. Despite these vulnerabilities, we have been hearing for years that the Federal Aviation Administration is removing ground-based navigation equipment relying on GPS for the NAS.
In 2006, the FAA started the transition to performance- based navigation (PBN) primarily using GPS and area navigation, or RNAV. The FAA has been removing selected
VORs – stations emitting very high frequency omni- directional range signals – from service and replacing them with flight procedures and route structure based on PBN.
The FAA realized that a VOR minimum operational network (MON) would need to be retained to provide a backup during GPS interference. With the MON as a backup, basic conventional navigation would be possible if GPS failed.
Navigation using the MON will not be as efficient as the new PBN route structure, but use of the MON will provide nearly continuous VOR signal across the NAS.
To repurpose the contiguous United States VOR network from the primary means of navigation to a backup, the VOR signal must be available starting at 5,000 feet above ground level. Coverage will exist below 5,000 feet but may not be continuous. To provide the required coverage, new VOR standard service volumes were established.
14 • KING AIR MAGAZINE
JANUARY 2025