Raytheon NSC 18 User Manual page 58

Head UP means the heading is upwards
Filter and Trails do not function in Head UP. Course UP is preferred.
The SHM is displayed relative to north. Rain and sea clutter will appear as high
level radar video.
(manual)
Step 1
+
Step 2
3748DOC020102
Operator Manual
North UP
North Marker
Figure: 2−22 North UP in (RM (R)) or (RM (T))
− The radar video is not stabilized by the gyro compass
− The anticlutter functions RAIN, SEA, FTC are not available
− Radar bearings are relative bearings (lateral)
− TRUE MOTION is not possible
− ARPA continues to function
D Manual
Head UP alignment (Step 2) can only be selected using the Relative Motion
preset (step 1).
D Automatic
If the gyro compass heading is not available, the radar will switch to
Head UP mode automatically.
WARNING
2−40
North UP
North Marker
Edition: 14.JAN.2005