A look at traffic systems: PCAS and TIS

At Oshkosh we received quite a few questions regarding new technology in aircraft electronic systems and how they differ from one another. Over the next few blog entries we will try and cover some of the questions people threw our way in an effort to help sort through the systems, acronyms, and what it can provide for your airplane. As always if you have questions you would like us to answer please send them to support@flightprep.com.

In this post we're going to take a look at a few different types of traffic avoidance systems. How they work, where they work, and what costs may be involved. While the best traffic systems out there are TCAS, TCAS 2 and the good 'ol mark 1 eyeball, the ones we'll look at today are more geared towards GA.

The first traffic system we'll take a look at is a portable system. PCAS, which stands for Portable Collision Avoidance System is a small box made by Zaon that sits on your glare shield and is able to "see" other aircraft transponders. Zaon's original PCAS technology was developed in 1999. Now, their current MRX/XRX line of collision avoidance systems incorporates the fourth generation of PCAS technology. Through this technology, transponder-equipped aircraft are detected and ranged, and the altitude is decoded. Above is an image depicting how the PCAS picks up traffic targets from an enroute radar and a TCAS interrogation signal.

Traffic can be spotted by the PCAS systems out to a range of 6 miles and +/- 2500 feet. The Zaon MRX, priced at around $550, is a small unit that looks like an auto radar detector and works on its own without the option to plug it into other systems like your EFB or some other handheld or panel mount. The slightly larger Zaon XRX (priced at $1299.99 from FlightPrep for just the XRX or $1499.99 from FlightPrep with Bluetooth capability) gives more information on traffic targets and also can be connected to a wide variety of other systems to display traffic. Unlike TIS, PCAS does not need a Mode S terminal radar to work. The PCAS basically gives you a 6 - 12 mile lateral by 5000 foot vertical bubble that should spot transponders from other aircraft almost anywhere you fly. Above is an image of what Zaon calls Average Interrogation "Coverage" Area: Military, Terminal, Enroute RADAR and TCAS Interrogation. See Zaon's website for a more in depth look at what areas are covered.

Unlike PCAS systems, Traffic Information Systems or TIS for short is not a portable system. TIS is a first generation traffic system that almost exclusively uses one of two certified and installed hardware boxes, the Garmin GTX 330 or the Honeywell Bendix KT73. One of these units would then send information to a display in the panel to show traffic info but only when in a Mode S terminal radar facility area. If you are equipped with TIS and flying in a Mode S radar coverage area you will have a very large range of traffic targets and very accurate information. Unfortunately the FAA has decided not to continue supporting Mode S terminal radars and the last Mode S radar site is scheduled to be replaced by late 2012. Here is an image of TIS information being displayed on a Garmin 430 unit. For more information on TIS, see AOPA's discussion page.

Next time we'll take a look at ADS-B. What it means, who can get it, and when it may be available. Until then we wish you frequent, happy, and safe flying!

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