Interesting question, "Turn x-ponder to standby when changing codes"? Back to the books. Our King Air is equipped with dual Collins TDR-94 mode-S units. Upon any change to the code selection, the control head waits approx 5 seconds before resuming squawk. I have to believe that most units today have this feature.-CY
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*deep inhale* I LOVE the smell of jet-a in the morning..