Garmin GTN 650 Pilot's Guide - Page 170

Foreword Getting Started NOTE: TIS will be unavailable at low altitudes in many areas of the U.S., particularly in mountainous regions. Also, when flying near the "floor" of radar coverage in a particular area, intruders below the client aircraft may not be detected by TIS. Xpdr Ctrl TIS information is collected one radar scan prior to the scan during which the uplink occurs. Therefore, the surveillance information is approximately Com/Nav five seconds old. In order to present the intruders in a "real time" position, the TIS ground station uses a "predictive algorithm" in its tracking software. FPL This algorithm uses track history data to extrapolate intruders to their expected Direct-To positions consistent with the time of display in the cockpit. Occasionally, aircraft maneuvering will cause this algorithm to induce errors in the display. These Proc errors primarily affect relative bearing information and traffic target track vector (it will lag); intruder distance and altitude will remain relatively accurate and Wpt Info may be used to assist in "see and avoid." Some of the more common examples of these errors follow: Map • When client or intruder aircraft maneuvers excessively or abruptly, the tracking algorithm may report incorrect horizontal position until the Traffic maneuvering aircraft stabilizes. Terrain • When a rapidly closing intruder is on a course that crosses the client aircraft course at a shallow angle (either overtaking or head on) and either aircraft Weather abruptly changes course within 0.25 NM, TIS may display the intruder on the opposite side of the client than it actually is. Nearest These are relatively rare occurrences and will be corrected in a few Music radar scans once the course has stabilized. Utilities System Messages Symbols Appendix Index 9-6 Garmin GTN 625/635/650 Pilot's Guide 190-01004-03 Rev. B