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

Verified

Key Takeaways:

The FAA's guidance has evolved, now permitting suitable RNAV systems, such as IFR GPS, to be used for navigating the final approach segment of conventional VOR, TACAN, or NDB instrument approaches.
This allowance is conditional: the underlying conventional NAVAID must be operational, its signal received, and actively monitored for final approach course alignment.
This regulatory change is reflected in recent AIM updates (2016) and avionics AFM supplements (e.g., Garmin GTN 2018), requiring pilots to confirm legality for their specific aircraft and avionics.

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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).