TM  1-1520-240-10 3-3-10            DISPLAY LEFT RIGHT REMARKS an option, enter his best esti- mate of ground speed and track angle. MN C, R, S, or H fol- lowed by a nu- meric code A failure occurred and the BACKUP mode used for manual navigation (MN) is the only means of valid naviga- tion. The operator may use the computer as a dead reck- oning devise by entering ground speed and track data. The operator should update present position as soon as possible, because it is pos- sible significant navigation er- rors may have accumulated. NG C, R, S, or H fol- lowed by a nu- meric code A failure has occurred in the system and the operator should not use the system. EN The 9V battery has failed. The system will still operate but all stored data will be lost when set is turned off. Data must be re-entered. Random display Random display A failure occurred and the op- erator should not use the sys- tem. 3-3-16.  Entering Data. This  initial  data  is  inserted  before  navigating  with  the doppler. a.  Spheroid of operation, when using UTM coordi- nates. b.  UTM or LAT/LONG coordinates of present posi- tion. c.  Magnetic  Variation  (MAG  VAR)  of  present  posi- tion. d.  Coordinates of desired destination - 0 through 5 and H: (6 through 9 are normally used for target store locations; but may also be used for destinations.) It is not necessary to enter all destinations in the same coordi- nate system. NOTE It is not necessary to enter destinations un- less steering information is required, unless it is desired to update present position by over- flying a destination, or unless a present posi- tion  MAG  VAR  computation  is  desired.  If  a present position MAG VAR running update is desired, destination MAG VAR must be enter- ed. The operator may enter one or more des- tination variations to effect the variation up- date; it is not necessary for all destinations to have associated MAG VAR entered. e.  Variation of destinations. 3-3-17.  Entering Spheroid and/or Variation. a.  MODE selector — UTM, LAT/LONG or BACKUP. b.  DISPLAY selector — SPH-VAR. c.  DEST DISP thumbwheel — P, numeral, or H as desired. d.  KYBD   pushbutton   —   Press.   Observe   display freezes  and  TGT  STR  indicator  blanks.  Press  KYBD pushbutton again and observe left display blanks. If no spheroid  data  is  to  be  entered,  KYBD  pushbutton  — Press again, go to step g. e.  Spheroid  data  (table  3-3-3)  —  Entry. (Example: IN0). Press keys 3, 3, 5, 5, and 0. Left display should indicate IN0. f.  ENT  key  —  Press  if  no  variation  data  are  to  be entered. g.  KYBD pushbutton — Press, if variation data is to be entered, and note right display blanks. h.  Variation data — Enter. (Example: E001.2, press keyboard keys 2, 2, 0, 0, 1 and 2. Press ENT key, the entire display will blank and TGT STR number will re- appear, display should indicate IN0 E001.2.) NOTE If operation is to occur in a region with relative- ly constant variation, the operator enters vari- ation only for present position, and the com- puter will use this value throughout the flight. Table  3-3-3   Spheroid Data Codes SPHEROID CODE AREA COV- ERED CLARKE 1866 CL6 United States north through North Pole CLARKE 1880 CLf Africa west through Algeria