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Why Two?

Gemini Sparkle

Key Takeaways:

  • The article traces the evolution of "dual" avionics installations in general aviation, questioning the persistent mindset for redundant equipment from essential early NAV/COMs to modern GPS systems.
  • Initially, the "dual NAV/COM" approach led to setups like twin Garmin GNS units, where the redundancy benefits for GPS were often debatable, and a single GNS paired with a dedicated MFD could offer greater functionality.
  • Modern integrated systems like the Garmin GTN 650/750 have revitalized the practical benefits of dual installations by combining GPS, NAV/COM, and robust MFD capabilities into compact units, offering two full-featured displays.
  • Despite these advancements, the author ultimately questions the necessity of fully redundant MFD/GPS/NAV/COM units when a primary EFIS MFD is present, suggesting a single integrated unit plus a basic NAV/COM often provides sufficient functionality.
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At my day job flying airliners I get a lot of idle time for my brain. To avoid the clich of that becoming the devil’s workshop, I try to occupy myself with deep thought. I’m not often successful, but on a recent rather long leg, I was. I’d just reviewed the sensor data for our single FMS and my mind began to look critically at our on-board equipment compared to what we see in general aviation, specifically the whole concept of “dual” installations of identical equipment.

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