Figure 11-17. The Area Surrounding the Aircraft for Coverage Using TIS.

It is important to remember that most systems display only a
specific maximum number of targets allowed. Therefore, it
does not mean that the targets displayed are the only aircraft
in the vicinity. The system displays only the closest aircraft.
In addition, the system does not display aircraft that are not
equipped with transponders. The display may not show any
aircraft; however, a Piper Cub with no transponder could be
flying in the area. TIS coverage can be sporadic and is not
available in some areas of the United States. Traffic advisory
software is to be utilized only for increased situational
awareness and not the sole means of traffic avoidance. There is
no substitute for a good visual scan of the surrounding sky.