OFF  ALT  ON  GND  TST  SBY  FLT ID  CRSR  FLT ID  BRT  IDT  VFR  XPDR  KT 73 TSD  Mode S Transponder  Mode S Sensor  Data link control display unit  SEL  MENU  RNG  DATA  BRT  VIEW NORM  2700 ft 1013mb  20 nm +02  0.0  -05  Figure 5-54. Concept of the traffic information system. Figure 3-51A. Theory of a typical alert system. Figure 5-55. Figure 5-56. A Skywatch System. 5-33