TM  1-1520-240-10 3-3-12            e.  FLY-TO DEST thumbwheel — Set to desired des- tination. The computer calculates a course between the destination and the helicopter position at the time the destination was selected. 3-3-22.  Flight Procedures. 3-3-23.  Update of Present Position from Stored Des- tination. a.  FLY-TO DEST thumbwheel — Set to destination to be overflown. b.  DISPLAY selector — DIST/BRG-TIME. c.  KYBD pushbutton — Press and release when heli- copter is over the destination. Display freezes upon re- lease of the pushbutton. NOTE If a present position update is not desired, as indicated by an approximately small value of distance to go on overflying the destination, set the DISPLAY selector to some other posi- tion; this aborts the update mode. d.  ENT key — Press if update is required. 3-3-24.  Update of Present Position from Land- mark. There  are  two  methods  for  updating  from  landmark. Method 1 is used if the landmark comes up unexpectedly and the operator needs time to determine the coordina- tes. Method 2 is used when the landmark update is antici- pated. a.  Method 1. (1) DISPLAY selector — PP. (2) KYBD pushbutton — Press as landmark is overflown. Present position display will freeze upon re- lease of pushbutton. (3) Compare landmark coordinates with those on display. NOTE If present position update is not desired, as indicated by a small difference between the display coordinates and the landmark coordi- nates, set the DISPLAY selector to some oth- er position; this aborts the update. (4) Landmark coordinates - Enter if difference warrants an update. (5) ENT key — Press if update is required. b.  Method 2. (1) DISPLAY selector — DEST/TGT. (2) DEST DISP thumbwheel — P. Present posi- tion coordinates should be displayed. (3) KYBD  pushbutton  —  Press,  observe  that display freezes. NOTE If present position update is not desired, as indicated by a small difference between the displayed   coordinates   and   the   landmark coordinates,  set  the  DISPLAY  selector  to some other position; this aborts the update. (4) Landmark coordinates — Manually enter via keyboard. (5) ENT  key  —  Press  when  overflying  land- mark. 3-3-25.  FLY-TO-DEST Operation. a.  When the FLY-TO-DEST thumbwheel is selected to a new position, the helicopter’s present position at the time is stored in the computer. A course is then computed from the helicopter’s present position, as stored, to the destination selected. If the helicopter deviates from this course, crosstrack error (XTK) is computed. b.  Range  and  bearing  to  destination,  current track made good, and track angel error (TKE) correction are computed from the helicopter’s present position to se- lected destination. 3-3-26.  Left-Right Steering Signals. Flying the shortest distance to the destination from pres- ent position: a.  FLY-TO-DEST thumbwheel — Select desired des- tination. NOTE If the desired destination is already selected but an updated course is needed, then the FLY-TO-DEST thumbwheel must be cycled to another destination and back so the computer will recalculate the new course. b.  DISPLAY selector — XTK/TKE. c.  Fly to keep the left display at L or R 000.0 and the right display to L or R 000. 3-3-27.  Target Store (TGT STR) Operation. Two methods may be used for target store operation. Method 1 is normally used when time is not available for preplaning a target store operation. Method 2 is used when time is available and it is desired to store a target in a specific DEST DISP position. a.  Method 1. (1) TGT STR pushbutton — Press when flying over target.