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2 Answers

Does the Garmin GDL 39 show mode c trafic?

Asked by: 1983 views Private Pilot

It's confusing,

dose the Garmin GDL 39 show regular transponder traffic?

or it will only show the new ADSB in/ ADSB out traffic ?

i am planing to buy one and link it to my Garmin 696 , any advise?


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2 Answers

  1. John D Collins on Oct 19, 2014

    Any ADS-B receiver will receive two types of traffic, directly via air to air reception of aircraft which are ADS-B Out equipped and indirectly by any broadcasts from the Ground Station (GBT). Here is the rub, the GBT will only broadcast traffic of aircraft that are just Mode A/C transponder equipped when an aircraft with ADS-B Out is in the vicinity of said traffic. Since 95% of the traffic is Mode A/C transponder traffic, the vast majority of the traffic will not be seen by the GDL39 or for that matter any ADS-B portable receiver, unless the aircraft is also equipped with ADS-B Out. I suspect your aircraft is not ADS-B Out equipped, and if this is true, you will see only a few percent of the traffic that could be a collision threat. Without ADS-B Out installed on the aircraft, a portable ADS-B receiver is next to useless when it comes to traffic. What the GDL39 and your 696 will do is provide you with weather for now. If and when you equip your aircraft with ADS-B Out, it will then provide a fairly complete picture of traffic around your position although there are limitations.

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  2. George on Oct 20, 2014

    John, thank you so much for a very well explanation.

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