Traffic Advisory System Technology Overview

What are the different types of Traffic System Technologies?  There are five basic types of technology for traffic detection and surveillance.

Types of Traffic System Technology

  1. TCAS
  2. TAS
  3. ADS-B
  4. Passive
  5. TIS

1. Traffic Collision Avoidance System (TCAS)

TCAS II systems are designed for Air Transport category and larger corporate jet aircraft; also known as, Airborne Collision Avoidance Systems ACAS.  The systems are mandated by Federal Aviation Administration (FAA) for Part 121 aircraft applications.

TCAS II systems issue visual and audio Resolution Advisories (RA) to the flight crew, relative to imminent threat aircraft for appropriate avoidance maneuvers, such as, Climb! Climb! or Monitor Vertical Speed!  They rely on active interrogation of transponders to analyze range, bearing, and relative altitude of detected aircraft.

TCAS II systems are heavy and very expensive typically costing more than $150,000.

TCAS I is a relatively lower-cost traffic avoidance system designed for Turboprop and light get aircraft. The system monitors traffic around the host airplane and presents approximate bearing and altitude in real time of other aircraft but does not offer any suggested flight crew action for collision threats.

TCAS I systems are designed to give 30-second warning at up to 1,200 knot closure rate. They also are too heavy and expensive for most GA aircraft and range in cost from $25K – $65K.

2. Traffic Advisory Systems (TAS)

Traffic Advisory Systems (TAS) are a lower cost version of TCAS I that were designed for general aviation aircraft.

Just as with TCAS I, TAS systems actively interrogate other nearby aircraft and provide Traffic Advisories (TA) in the event that an intruder aircraft is within 30 seconds of imminent collision. The four most popular TAS systems for general aviation are:

  • Avidyne‘s TAS600 Series
  • Garmin GTS800 Traffic
  • L3 Skywatch Traffic
  • Honeywell‘s KTA-870 system.

Each of these systems are designed to meet the performance guidelines of TSO-C147, and detect intruder aircraft based on traffic advisory system TAS design criteria.

Cirrus Perspective GTS aircraft employ one of the following three Active Traffic Advisory Systems from: Garmin GTS 800 Traffic; Avidyne TAS600 Series and L-3 Skywatch Traffic.  Check the POH for the type system installed.  Original cost was around $8,500.

3. Automatic Dependent Service – Broadcast (ADS-B)

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, TAS systems Cirrus Perspective are upgradable to ADS-B In. ADS-B In provides longer-range traffic advisories with greater accuracy than other traffic advisory technologies used today.

ADS-B Out will provide Automatic sending of messages, without interrogation; with message data Dependent on the Global Positioning System (GPS) and ground based equipment for location, altitude and velocity; intended for real-time Surveillance primarily to ATC and secondarily Broadcast to everyone else.

4. Passive Traffic Detection Devices (TCAD/PCAS)

Passive traffic systems are designed to listen to the transponders of nearby traffic that are replying to the interrogations of an ATC Radar facility or other active systems like TCAS or TAS equipped aircraft.  These products will not detect aircraft whose transponders are not actively replying and are fundamentally ineffective outside of radar coverage areas.

Many passive portable systems make traffic detection more affordable, but pilots need to understand the limitations of the particular system they might be using.

5. Traffic Information Service (TIS)

TIS is a passive request and response technology that requires ground based equipment to identify nearby potential threat traffic.  In April 2005, the FAA issued a decision paper, Discontinuation of Mode S Traffic Information Service (TIS) at Sites Where ASR-7/8 Radars Are Replaced by ASR-11.  Many of these TIS systems are now being phased out of service.

Traffic Advisory Systems (TAS) now offer GA aircraft an affordable effective technology which advances safety of flight and is upgradeable to ADS-B In.

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