Garmin 496 Manuale Proprietario

TIS information is collected one radar scan prior to the scan during 

which the uplink occurs. Therefore, the surveillance information 

is approximately 5 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. This algorithm uses track 

history data to extrapolate intruders to their expected positions 

consistent with the time of display in the cockpit. Occasionally, 

aircraft maneuvering causes this algorithm to induce errors in the 

GPSMAP 496 screen. These errors primarily affect relative bearing 

information and traffic target track vector (it will lag); intruder 

distance and altitude remains relatively accurate and may be used to 

assist in “see and avoid.” Some of the more common examples of 

these errors include:

•  When client or intruder aircraft maneuvers excessively or 

abruptly, the tracking algorithm can report incorrect horizontal 

position until the maneuvering aircraft stabilizes.

•  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 abruptly changes course within 

¼ nm, TIS may show the intruder on the opposite side of the 

client than it actually is.

These are relatively rare occurrences and is corrected in a few radar 

scans once the course has stabilized.
Users of TIS can render valuable assistance in the correction 

of malfunctions by reporting their observations of undesirable 

performance. Reporters should identify the time of observation, 

location, type and identity of aircraft, and describe the condition 

observed; the type of transponder processor and software in use can 

also be useful information. Since TIS performance is monitored 

by maintenance personnel rather than ATC, it is suggested that 

malfunctions be reported in the following ways:

•  By telephone to the nearest Flight Service Station (FSS) 

facility.

•  By FAA Form 8000-7, Safety Improvement Report, a 

postage-paid card designed for this purpose. These cards can 

be obtained at FAA FSSs, General Aviation District Offices, 

Flight Standards District Offices, and General Aviation Fixed 

Based Operations.

GPSMAP 496 Owner’s Manual 

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TIS > 

TIS L

IMITATIONS