Even though the certified boxes do fail, they are tested to a much higher standard (DO 160) than the mass produced portable products. In the long run , the certified box might outlast the mass produced product. How many KX 155's are out there still providing reliable service?
Even though the FAA has allowed the use of the mass produced product in the cockpit of the airlines, I'm pretty sure it's in an advisory capacity only, ie charts. The primary flight displays and maps are still the tried and true FAA certified avionics.
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Jon Hadlich
AI Systems
(541) 815-7381