AIM 

9/5/24 

vertically of the client aircraft (see FIG 4

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5

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3, TIS Proximity Coverage Volume). The range of a target reported 

at a distance greater than 7 NM only indicates that this target will be a threat within 34 seconds and does not 

display a precise distance. TIS will alert the pilot to aircraft (under surveillance of the Mode S radar) that are 

estimated to be within 34 seconds of potential collision, regardless of distance or altitude. TIS surveillance data 

is derived from the same radar used by ATC; this data is uplinked to the client aircraft on each radar scan 

(nominally every 5 seconds). 

b.  Requirements. 

1. 

In order to use TIS, the client and any intruder aircraft must be equipped with the appropriate cockpit 

equipment and fly within the radar coverage of a Mode S radar capable of providing TIS. Typically, this will be 

within 55 NM of the sites depicted in FIG 4

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5

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4, Terminal Mode S Radar Sites. ATC communication is not a 

requirement to receive TIS, although it may be required by the particular airspace or flight operations in which 

TIS is being used. 

FIG 4

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5

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3 

TIS Proximity Coverage Volume 

4

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5

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6 

Surveillance Systems