Overlay Approaches

Lets connect some dots. In 1969, NARCO (now defunct) introduced the CLC-60 VORTAC Offset Control Panel that allowed navigation to a phantom fix defined as a distance and direction (rho-theta) from an existing VORTAC. It was touted as the first RNAV system. In the 80s, Bendix/Kings KNS-80 Integrated Navigation System might be considered the first practical RNAV navigator (it had VOR, LOC, DME, RNAV, and GS). Like the CLC-60, it could electronically move a VORTAC and was IFR certified.

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Sunday, February 17, 2019 at 12:00 AM ET

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Key Takeaways:

Recent FAA guidance (AIM and updated aircraft flight manual supplements) now permits using an IFR GPS as the primary navigation source for the final approach segment of VOR or NDB approaches.
This capability is contingent on the underlying ground-based NAVAID (VOR or NDB) being operational and actively monitored by the pilot for final approach course alignment.
While offering flexibility for approaches without modern RNAV options, dedicated RNAV (GPS) approaches typically provide greater precision and vertical guidance, often making them a preferred choice.

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During an instrument proficiency check, or for that matter an instrument check ride, a common question is, “What does the title of an approach chart indicate? For Example: LOC/DME RWY 18 or VOR RWY 20.” And a follow-up question, “What does ‘ADF Required’ on an approach chart imply (not in the title)?”

Of course, we all know the answers to the questions. Right? The title of the approach indicates what equipment is required to fly the final approach segment (FAS).