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Dual-Think Revisited

Gemini Sparkle

Key Takeaways:

  • The author initially argued against the need for dual GPS navigators, believing VORs provided sufficient backup and MFDs offered cheaper screen real estate.
  • A personal experiment revealed that disabling the single GPS rendered the primary flight display (PFD) and autopilot useless because the air-data computer and AHRS rely on GPS data for accurate information.
  • This discovery led the author to revise his stance, recognizing the critical importance of a secondary GPS source for feeding flight instruments and ensuring system redundancy, even if not a full second navigator.
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Years ago, I wrote an article for these pages in which I opined that there was no need or fiscal justification for the dual GPS navigators that seem so common in a well-equipped panel. I stand by that, but times have changed.

In the article, I first explored where that “dual-think” came from. Many of us remember life before GPS or LORAN. We had to navigate using VORs. While possible with a single receiver, it was much easier with two. Plus, having two coms was a convenience where we could use one with ATC and the other to check weather or perform other chores. Thus, dual nav/coms became the standard. And that standard simply endured with Garmin’s GNS-series GPS/nav/coms.

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