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What About Portable ADS-B Receivers?

While portable ADS-B In receivers are popular, they do not fulfill the FAA’s 2020 mandate for ADS-B Out. In addition, if they’re used in an aircraft that does not yet broadcast an ADS-B Out signal, traffic information displayed will be incomplete. That’s because ADS-B traffic information is not continually broadcast to airborne receivers, like weather information is.

Instead, traffic is broadcast when an airplane reports its position using ADS-B Out. Each traffic broadcast is tailored to the requesting aircraft’s position and includes tracked aircraft within a 15-nm circle around that aircraft, extending 3,500 feet above and below. Think of this airspace as the ADS-B Out aircraft’s puck, because it is shaped like a hockey puck. So an aircraft with ADS-B In that does not have ADS-B Out will receive traffic information, but traffic very close to the receiving aircraft may not be displayed—remember, it’s showing traffic in another aircraft’s puck, and the position of that aircraft is unknown.

Portable ADS-B In receivers can provide helpful situational awareness, as well as weather information, but this traffic limitation must be kept in mind.

After ADS-B Out is required, on January 1, 2020, a portable ADS-B receiver can serve as your ADS-B In traffic solution; and as soon as an aircraft owner adds ADS-B Out, a portable will provide all available traffic information (it may not show all aircraft in nonradar areas, where ADS-B is not required, or aircraft without electrical systems).

For more information on this topic, see “Technology: Who’s Seeing Whom?” (July 2014 AOPA Pilot).