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Avionics

Panel Mount Traffic: Avidynes TAS Prevails

Fear of a mid-air collision ranks high on the demon list for many owners-high enough that there's a lively market in panel-mounted traffic systems that cost the better part of $20,000 or more to install. There's also intense competition in the field, leading us to ask if one system is really better enough than another to recommend it over its competitors.The short answer is that performance doesnt drive the traffic box choice as much as price and display preference does. All of the systems weve tried adequately do the basic job of seeing threatening traffic and although none have a perfect record of seeing every threat airplane, we didnt see enough difference between the products to recommend one over another solely on performance.

Larry Anglisano
Verified

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r of a mid-air collision ranks high on the demon list for many owners-high enough that there’s a lively market in panel-mounted traffic systems that cost the better part of $20,000 or more to install. There’s also intense competition in the field, leading us to ask if one system is really better enough than another to recommend it over its competitors.The short answer is that performance doesnt drive the traffic box choice as much as price and display preference does. All of the systems weve tried adequately do the basic job of seeing threatening traffic and although none have a perfect record of seeing every threat airplane, we didnt see

Panel Mount Traffic

enough difference between the products to recommend one over another solely on performance.

We tested panel mount traffic systems against each other as part of the roundup of portable traffic squawkers that appeared in the September 2007 issue of Aviation Consumer. For this report, we didnt specifically test the Bendix/King upper tier system (KTA-870), but we have flown with it and the KT-73 system in the past. The active KTA-870s performance is comparable to the Skywatch and Avidyne system and the TIS-based KT-73 works about as we’ll as the Garmin GTX330.

Panel or Portable?

Our exhaustive trials of all the portable traffic systems revealed that they are surprisingly good performers. To be sure, they don’t see all the traffic and because theyre passive listeners, they depend on nearby transponders being illuminated by either ATC radar or another active traffic system. Fortunately, there’s enough of each out there that transponders are always replying, so a passive system has a good chance of hearing anything nearby.

But “most of the time” isn’t the same as “always,” hence the popularity of active panel-mounted systems. Active systems are of two types: self-contained, dedicated traffic systems that do their own interrogation on the same principle used by top-tier TCAS systems in airliners and the TIS-based (FAA Traffic Information Service) concept. TIS-based systems arent really active but are something in between active interrogators and passive listeners.

The TIS system collects traffic data from FAA radar sites and broadcasts it through a Mode-S transponder link to equipped aircraft within a defined service area. All the processing horsepower is contained in the ATC facility providing the service and it tracks only targets within its coverage area. Two products utilize this service, Garmins GTX330 and Bendix/Kings KT-73 Mode-S transponders.

Both work the same way, receiving the ground-based data from the ATC facility and displaying the results on a discrete display, either one of the Garmin GNS-series navigators or a multi-function display. TIS is an effective system but, as weve reported previously, the FAA is slowly phasing it out as it upgrades to ASR-11 terminal radar, which wont have the TIS module and thus no TIS service. (Several radar sites have already been phased out.) Furthermore, TIS works only in those area served by the terminal radar; if the Mode-S transponder cant receive the ground signal, it cant display traffic.

But true active systems-L-3s Skywatch, the Bendix/King KTA-870 and Avidynes TAS series-do their own pinging of nearby transponders, just like the TCAS systems on which they are modeled. In theory, this means active systems should see every transponder-equipped aircraft that might be a threat. The reality is that they fall a little short of that, although not much. If you opt for any of the active systems, youre probably doing all you can do to avoid a surprise paint swap.

Flight Trials

We flew with all of the portables and three of the active systems-the Skywatch, the TIS-based Garmin GTX330 and the SKY497 from L-3. As explained in the September 2007 report, we hoped to use the panel-mount systems as truth against the portables, which either don’t report azimuth and distance, or do so with limited accuracy. Thats less a complaint and more a limitation of portable technology. We wouldnt reasonably expect an $1800 portable to perform as we’ll as a $20,000 panel system.

Larry Anglisano

Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.