The Parenthetical Fix

Like many of our clinics, this one started with a readers letter. This particular fellow was a flight instructor who had to go old-school with a Private student in a Diamond DA20 equipped with a Garmin GNS 430 GPS. They were following V86-365 from the Bozeman VOR to the Livingston VOR at night through the mountains. Happily motoring along on GPS, they ran into a snag with the bend in the airway.

jwanwest

Tuesday, December 02, 2014 at 12:00 AM ET

Verified

Key Takeaways:

A flight instructor and student struggled to navigate an airway bend using a single GPS/VOR because crucial intersection fixes, known as Computer Navigation Fixes (CNFs), are not marked on VFR sectional charts.
CNFs like "ZUBLI" are found on IFR low-altitude en-route charts, designed specifically for GPS navigators to define airway turns, but are omitted from VFR charts as they are deemed unnecessary for visual flight.
To accurately navigate these airway bends when relying on GPS, pilots need to consult IFR charts for CNF names or employ various in-flight GPS workarounds if an IFR chart is unavailable.

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Like many of our clinics, this one started with a reader’s letter. This particular fellow was a flight instructor who had to go “old-school” with a Private student in a Diamond DA20 equipped with a Garmin GNS 430 GPS. They were following V86-365 from the Bozeman VOR to the Livingston VOR at night through the mountains. Happily motoring along on GPS, they ran into a snag with the bend in the airway.

With two VORs, this is a no brainer: Track R-110 from BZN on one Nav and dial up R-246 to LVM on the other. When the second Nav needle centers, turn left and continue. It’s a bit tougher with one GPS/Nav. You can’t load the airway on a GNS 430 and the bend had no fix name associated with it on the VFR chart. They ended up flying the right distance outbound from BZN via the VOR part of the GPS and then using GPS direct for the leg to LVM.