Traffic Advisory System, Design, Cirrus Perspective by Garmin

What is the design and concept of the Avidyne TAS600 SeriesTraffic Advisory System for the Cirrus SR22?  The System interrogates transponders from nearby aircraft and warns you when the calculated time to closest approach of any intruder and the protected area around your aircraft reaches a 30 second threshold.  

The TAS600 Series sends continuous interrogations up to 56 times per second, and can

Cirrus Perspective Nav Page with Traffic by wikiWings.Wordpress.com
Cirrus Perspective Nav Page with Traffic by wikiWings.Wordpress.com

receive replies from Mode A, C, or E transponders.  It is designed to provide “real-time” collision alerts with a full 30-second decision time at a closure rate of up to 1,200 knots.

Pilots sometimes call this type of system “active surveillance” because there’s no passive reliance on ground-based radar systems to detect threat aircraft.

The Avidyne TAS600 Series Traffic Advisory System uses a dual antenna system coupled to an onboard interrogator and processor and an altitude reporting transponder for its real-time acquisition of air-to-air traffic information.

“The vertical separation of the host and intruder is determined by comparing the decoded altitude replies to the host’s altitude (from the altitude encoder). The range is determined using radar time of arrival technique. Bearing to the traffic is determined using the dual directional antennas, on the top and bottom of the aircraft. The altitude data from the intruder is referenced to pressure altitude (29.92 inches, barometric pressure adjusted to sea level), as is the onboard encoder, thus separation is not dependent on the altimeter setting.”

The top antenna provides directional surveillance front and aft while the bottom antenna provides directional surveillance left and right of the aircraft.  Avidyne’s dual-antenna architecture, delivers 360 degree interrogation and reception, and provides greater accuracy for range and bearing resolution of an intruder aircraft.  “Portable systems make traffic detection more affordable, but because they only have one antenna and very little ground plane, they can be susceptible to shadowing and poor reception.”

Avidyne’s published range for the TAS600 is 7nm with 3,500 feet of relative altitudes covered above and below your aircraft and a maximum operating altitude of 18,500 feet.  The TAS610 has a 12nm range, 3,500 feet of relative altitude coverage with a maximum operating altitude of 25,000 feet.

Current, TAS systems are transponder based.  So, if a nearby aircraft has a transponder, but it is turned-off or not functioning, then detection of the aircraft will not be possible.  The ADS-B Out Mandate addresses this issue and will provide greater data accuracy to further advance safety in flight.

By January 1, 2020 all aircraft operating in the US in class A, B, C airspace or in class E airspace above 10,000 MSL will need ADS-B Out equipment.  Currently, there is no mandate for ADS-B In; however, the Avidyne TAS600 Series Active Surveillance Traffic Systems are fully upgradable to ADS-B In.

As of 2012, Avidyne reported having more than 10,000 Traffic Systems in service, and promotes the TAS600 Series as the smallest, lightest, most affordable TAS product in the general aviation marketplace today.  List price is $8,490.

Sources:

  1. Avidyne TAS600 Series Pilot’s Guide, P/N 600-00145-000 (32-2352) Rev 7, 11 Mar 2011
  2. Avidyne, Choosing a Traffic System, A Comprehensive Buyers Guide, February 2012
  3. Cirrus Perspective by Garmin – Pilot’s Guide for the SR22, 2008, pp. 342-357

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