Dead Reckoning in IFR

Tuesday, February 23, 2021 at 11:33 AM ET

Verified

VORs are disappearing around larger airports, making even short VOR based short routes challenging. (Shaded VORs are on the MON hit list.)

Key Takeaways:

The FAA is transitioning to a GPS-centric Performance Based Navigation (PBN) system, leading to the widespread decommissioning of VORs and reducing reliance on ground-based navaids for en-route navigation.
Modern IFR en-route navigation primarily requires certified Area Navigation (RNAV) equipment that meets specific Required Navigation Performance (RNP) criteria for accuracy and safety (e.g., RNAV 2 for 2 NM accuracy).
"Dead reckoning" (DR) as a primary means of IFR en-route navigation is generally not acceptable in the current National Airspace System because it does not meet the necessary performance standards for separation and obstruction clearance.
However, dead reckoning is specifically permitted and often required in very limited, vetted scenarios, such as navigating through MEA gaps on airways, certain approach transitions, and specific Obstacle Departure Procedures.

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GPS in general aviation aircraft has become ubiquitous. So much so that the FAA’s move to a Performance Based Navigation (PBN) world based primarily on the Global Navigation Satellite System (GNSS) is well underway. We are already seeing the cancellation of “redundant” and “underutilized” VOR (and NDB) approaches. For en-route navigation, we have the Minimum Operational Network (MON) initiative, which plans to reduce reliance on VORs and the associated Victor airways in the Lower 48 while retaining just enough stations to act as a backup to a possible widespread GNSS outage. The goal is to shut down a little over a third of the VORs by 2025.

Now What?

Despite the prevalence of IFR GPS navigators, not all aircraft are so equipped. Or, even if they are GPS equipped, some pilots still prefer to fly in the familiar comfort of Victor Airways, whether they use VOR or GPS navigation. This raises questions about what to do as VORs and their associated airways disappear.