This module covers the communications and navigation systems on-board modern aircraft. Examples of topics include very high frequency / high frequency (VHF / HF) communications systems, GPS systems, inertial navigation, Instrument Landing Systems (ILS), and Traffi c Collision and Avoidance Systems (TCAS). This fulfills the communications (ATA 23) and navigation (ATA 34) knowledge requirements in Singapore Air Worthiness Requirements Part 66 (SAR-66) Module 13 (Aircraft Aerodynamics, Structures and Systems).