TM 1-1510-225-10 3D-50 6.   Once  established  on  the  inbound  course, the   LEG   mode   will   again   need   to   be selected so that proper approach operation   and   waypoint   sequencing   will occur. NOTE It is mandatory that the unit is in the LEG mode with the FAF as the active waypoint before   crossing   the   FAF   to   activate   the approach   active   mode   and   change   to   ± 0.3 nm  scale  factor.    The  CDI  scale  factor changes from ± 1.0 nm to ± 0.3 nm over the 2  miles  to  the  FAF.    Delaying  the  switch from  OBS  to  LEG  mode  compresses  the scale  factor  change.    This  will  make  the transition  more  abrupt.    If  the  switch  from OBS to LEG is delayed too long, it will not be  possible  for  the  KLN  90B  to  change  to the approach active mode. 7.   When  the  aircraft  is  2  nm  from  the  FAF, the  KLN  90B  will  verify  the  proper  GPS integrity is available.  If integrity monitoring is available for the approach, the KLN 90B will change to the approach active mode.   This  will  be  annunciated  on  the  external approach status annunciator as well as on the  KLN  90B.    The  CDI  scale  factor  will also  start  to  change  from  ±  1.0  nm  to  ± 0.3 nm. 8.   Normal waypoint alerting will occur as the aircraft passes the final approach fix.  The leg   from   the   final   approach   fix   to   the missed approach point will become active and   the   CDI   scale   factor   will   remain   at ± 0.3   nm.      If   the   auto   scale   factor   was selected  on  the  Super  NAV  5  page,  the scale  factor  will  zoom  in  on  the  airport  as the  aircraft  gets  closer  and  closer  to  the missed   approach   point.    Eventually  the map   scale   changes   to   1   nm   and   the runway  diagram  becomes  visible  on  the map. 9.   The missed approach instructions may call for    a    climbing    turn    to    a    heading    to intercept a course to the missed approach holding  point.    To  fly  this  with  the  KLN 90B,  it  will  be  necessary  to  put  the  KLN 90B into the OBS mode.  Make the missed approach holding point the active waypoint.  Change the selected course on the external EHSI to the published course to the missed approach holding point.  Fly the  heading  until  intercepting  the  course, then turn and track the course. NOTE The KLN 90B must be in the OBS mode for holding. 10.    Once    the    aircraft    reaches    the    missed approach holding point, perform the appropriate holding pattern entry.  Set the selected    course    on    the    EHSI    to    the inbound holding course. j.    DME  Arc  Approach.    DME  arc  procedures with  the  KLN  90B  are  different  from  traditional  VOR and DME equipment.  The KLN 90B provides left/right guidance around the arc. (1)   ATC  assigns  the  approach.    Turn  to  the APT 8 page  for the destination to select the approach.   When the approach is selected, the KLN 90B presents the IAF selection page. (2)   Two   of   the   lAF's   may   be   in   the   form DxxxY.        These    two    waypoints    are    the    database identifiers for the ends of the arc.  D040L means DME arc point 040 is the radial on which the waypoint lies, and L indicates the distance of the arc.  L is the twelfth letter  of  the  alphabet  so  L  indicates  that  this  is  the 12 NM DME arc. CAUTION The  KLN  90B  does  not  take  into  account the geometry of the active flight plan when determining  the  arc  intercept  point.    This point is defined solely on the present radial and    the    defined    arc    distance    from    the reference VOR.  For this reason, it is better to delay selecting approaches that contain DME arcs until the  aircraft  is  closer  to  the destination. NOTE If   the   present   radial   from   the   reference VOR is outside of the defined arc, the KLN 90B will default to the beginning of the arc. (3)   The  KLN  90B  recognizes  if  this  point  is associated with a DME arc.  Once the arc waypoint is chosen, the KLN 90B determines on what radial of the reference  VOR  is  presently  located.    A  waypoint  is created   that   is   located   at   the   intersection   of   the present radial and the DME arc.  This waypoint is the first waypoint in the list of waypoints presented on the APT 8 page before loading the approach into the flight plan.  This waypoint is named in the same convention as above.