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 actively transitioning to a GPS-based Performance Based Navigation (PBN) system, leading to the decommissioning of VORs and raising concerns about IFR navigation for aircraft not equipped with IFR-certified GPS.
"Dead reckoning" (DR) is generally not a viable primary method for IFR en-route navigation in today's airspace due to stringent Required Navigation Performance (RNP) standards for accuracy and reliability.
Despite its unsuitability for general en-route IFR, dead reckoning is still permitted and sometimes necessary in specific, limited scenarios, such as bridging MEA gaps on VOR airways, certain approach transitions, published visual flight paths, and 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.