TM 1-1520-238-10 4-18 b. Conventional Uses: NOTE If an erroneous magnetic variation is en- tered into SP1, the aircraft heading scale and the HSI will also indicate that amount of error. Entries of magnetic headings greater than 360 or a magnetic variation entered greater than 179.9 will be ignored. The message ERROR will be displayed on the upper left of the display field prompt- ing the operator to re-enter valid data . (1) Magnetic variation. Use E for East and W for West, as appropriate. (2) Grid Convergence . Use E for East and W for West, as appropriate. Data may be obtained from G-M angle diagram on UTM maps if applicable. (3) Spheroid. Use the same codes utilized by the doppler. (4) Latitude. Use – for North and S for South, as appropriate. 4.17.2 Waypoint/Targeting Coordinate Data Stor- ing. Up to ten sets of coordinate data may be stored in the FCC at anytime. Two methods can be used to store coordinate data; these are either the data entry keyboard, or by use of the store (ST) position of the UPDT/ST switch on the ORT LHG. The coordinate data are displayed as four pages of a coordinate data menu. The various pages may be paged by using the SPACE key on the DEK. An example page is shown below: TRGT 0 11S QG51285172A +0820’ 1 NO DATA 2 NO DATA a. Store Coordinate Data Using DEK. To enter data input the appropriate coordinate data address. The cursor will jump to the first position for data entry, i.e., grid zone. Either input the specific grid zone or use the SPACE key for automatic entry if the coordinate data grid zone is the same as the aircrafts current present position of the 100 KM ID; either input the data or use the SPACE key followed by the eight or six–digit coordinates. Pressing the SPACE key will automatically enter the A for the altitude. If the altitude of the coordinate data is above sea level di- rectly input the numbers; if necessary a leading zero is re- quired. The plus sign will be automatically entered; if coor- dinate data is below sea level the minus sign must be input prior to the numeric value. If a particular storage location has no data the message NO DATA will be shown. If it is desired to clear a specific storage location, key in the letter C followed by the desired coordinate data storage location address. The location will be cleared and the message NO DATA will be dis- played. b. Storing Coordinate Data Using UPDT/ST Switch. 1. Waypoint/target index – Desired storage loca- tion. 2. Enter range, aircraft to waypoint/target. NOTE Range to geographic feature or object must be input to the FCC. This may be accom- plished by three means: 1. Manual range in- put through the keyboard (determined from a map or by estimation); 2. Automatically calculated range based on LOS angles from selected sight; 3. Laser range input by firing the laser after placing reticle on feature or object (This is the most accurate range data). 3. Place reticle of selected sight on the geographic feature or object. 4. UPDT/ST – ST (Waypoint/target coordinate data will be automatically calculated and placed in the location specified by the index.) 4.17.3 Waypoint/Targeting Position Update. NOTE This subsystem of the waypoint/targeting calculates the present position of the heli- copter based on previously stored coordi- nate data. The update present position is stored within the FCC and NOT automati- cally sent to the doppler navigation system. a. Position Update. 1. Waypoint/target indexer – index of location of previously stored coordinate data. 2. Enter range, helicopter to coordinate data. See explanation under storing coordinate data [para 4.17.1 (2)].