Finding Non-Precision

As we move forward in time with the proliferation of LPV approaches, the phaseout of non-precision approaches using ground-based navaids such as VOR, NDB, and LOC-only will result in fewer and fewer non-precision approaches. Furthermore, some WAAS navigators often provide an advisory glideslope to non-precision RNAV approaches: LNAV+V and LP+V. The +V refers to the advisory glideslope. An LP (localizer performance) approach is a non-precision RNAV approach that requires WAAS. Bottom line: there is almost always an electronic glideslope lurking in the shadows.

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Monday, July 01, 2019 at 12:00 AM ET

Verified

Key Takeaways:

The aviation landscape is increasingly dominated by GPS-based APV (Approaches with Vertical Guidance) like LPV, which provide precision-like electronic glideslopes, making traditional non-precision approaches (e.g., VOR, NDB, LOC-only) scarce.
This shift creates a challenge for pilots needing to practice or demonstrate proficiency in non-precision approaches, as required for certifications and checks, because most modern GPS approaches now provide vertical guidance.
To practice non-precision approaches, pilots with WAAS-equipped GPS can disable WAAS (SBAS) in their navigators, which removes the electronic glideslope and converts APV approaches to LNAV approaches without vertical guidance, though this may temporarily disable ADS-B Out.

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With the advent of GPS approaches in the 1990’s and early 2000’s, we had many more opportunities to practice and fly non-precision approaches. Today in the U.S., with WAAS (wide area augmentation system), the reduction of VORs and the near elimination of NDBs, there are fewer and fewer available non-precision approaches. The result is more precision-like approaches which undoubtedly improves safety.

I say “precision-like” approaches because the only true precision approach available to us is the ILS with a ground-based glideslope transmitter. On the other hand, due to some technical differences that are immaterial to pilots, most RNAV (GPS) approaches with WAAS have an electronic glideslope and are referred to as APV (approaches with vertical guidance).