Common Error: Skipping the Preflight Weather  Briefing Traffic Data Systems Traffic Data Systems Using Onboard Sensing  Equipment Traffic Data Systems Receiving Information From  Ground-based Facilities Traffic Display Symbology +03 Non-Threat Traffic Outside of protected distance and altitude range. Proximity Intruder Traffic Within protected distance and altitude range, but  still not considered a threat. Traffic Advisory (TA) Within protected range and considered a threat.  TCAS will issue an aural warning (e.g.,  Traffic!  Traffic! ). Resolution Advisory (RA) Within protected range and considered an immediate  threat. TCAS will issue a vertical avoidance  command (e.g.,  Climb! Climb! Climb! ). Figure 5-19. Traffic display symbology. approximately 40‑second range of the aircraft. Traffic  advisories take the form of an aural alert: “Traffic! Traffic!” Advanced TCAS systems (TCAS II) can also issue a  resolution advisory (RA) when another active transponder‑  equipped aircraft comes within an approximately 25‑second  range of the aircraft. RAs take the form of an avoidance  command that instructs you how to fly the aircraft in order  to avoid the threat. An aural alert is issued that instructs the  pilot to perform a vertical avoidance maneuver. Example  aural alerts are: “Climb! Climb!” and “Descend! Descend!” TCAS and traffic advisory systems use similar symbology to  present traffic information.  Figure 5-19  shows four common  traffic symbols used on traffic displays. The resolution  advisory symbols appear only when an advanced TCAS II  system is used. The colors used to display traffic symbols  vary with the capabilities of the display. The easy availability of weather information in the cockpit  can lure you to skip the preflight weather briefing. Time  pressure adds further incentive to simply jump in and go.  Keep in mind that flight services stations (FSS)/automated  flight service stations (AFSS) offer many advantages over  an advanced weather data system, so do not use advanced  avionics weather data systems as a substitute for a pre-flight  weather briefing. As a simple example, when talking to an  FSS/AFSS weather briefer, it is possible to get a better overall  picture of the weather system and pilot reports not yet entered  into the system. The FSS/AFSS briefer can also supply more  Notice to Airmen (NOTAM) and other detailed information  for your particular route of flight; without such briefing, the  pilot might expend many precious moments searching for  a critical bit of information, instead of managing the flight.  Often, it is much easier to get a thorough briefing on the  ground than attempting to read small reports on a bouncing  MFD in a small airplane in turbulent conditions. A traffic data system is designed to help you visually acquire  and remain aware of nearby aircraft that pose potential  collision threats. All traffic data systems provide aural alerts  when the aircraft comes within a certain distance of any other  detected aircraft. Traffic data systems coupled with MFDs can  provide visual representations of surrounding traffic. Most  traffic data systems allow you to set the sensitivity of the  system and display only traffic that exists within a specific  distance from the aircraft. There are two basic types of traffic data systems available  today: one using onboard sensors to detect nearby aircraft, the  other relying on traffic information transmitted from ground  facilities to the cockpit. Despite their many advantages, TCAS and traffic advisory  systems have several important limitations. For example,  TCAS and traffic advisory systems cannot detect aircraft that  do not have active transponders. Another limitation of TCAS  and traffic advisory systems is that they give unwanted alerts  when the pilot is purposefully operating in the vicinity of  other aircraft. For example, two aircraft making approaches  to parallel runways will probably receive traffic alerts. These  alerts can be distracting. Traffic collision avoidance systems (TCAS) and traffic  advisory (TA) systems use onboard sensing equipment to  locate nearby aircraft and provide alerts and advisories. Both  TCAS and TA systems work by querying the transponders of  nearby aircraft to determine their distance, bearing, altitude,  and movement relative to your aircraft. In addition, TCAS  and TA systems use Mode C information from transponders  to determine altitude and vertical movement of surrounding  aircraft. Using these capabilities, TCAS and TA systems  provide traffic alerts and advisories. The traffic information service (TIS) is a second type of  traffic data system. Unlike TCAS, the TIS system does not  require each aircraft to have an onboard sensor that locates  nearby aircraft. However, each aircraft must have operational  TCAS I and TA systems can issue a TA whenever another  active transponder‑equipped aircraft comes within an  5-14