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AN/ASN-128 Doppler Navigation System

Self-contained Doppler navigation system

AN/ASN-128 Self-contained Doppler navigation system The AN/ASN-128 self-contained Doppler navigation system provides three axes of velocity, and a continuous navigation solution for present position. These systems compute distance, bearing, and time to a selected destination, and track angle error and distance-off-course to assist in navigating to that destination.



  • Autonomous point-to-point navigation
  • Accurate hover velocities
  • Two-level maintenance
  • No flight line test equipment
  • Simple operation
  • High reliability
  • Low cost
  • Built-in test

Steering Hover Indicator Unit (Optional)

The Steering Hover Indicator Unit (SHIU) has two modes of operation. In the navigation mode, the SHIU provides the pilot with a display of ground speed, distance-to-go, and left-to-right steering information to the destination selected on the control display unit.

In the hover mode, the three pointers indicate the values of three orthogonal components of aircraft ground velocity (along heading, across heading, and vertical). By flying the aircraft to maintain these displayed values at zero, the pilot can hover the helicopter without visual reference to the ground.