The obs mode – BendixKing KLN 89B - Pilots Guide User Manual
Navigation is provided along the great circle path between two
waypoints. As you probably know, great circle navigation is the
shortest distance between two points located on the earth's
surface. In the case of Direct To operation, the "from" waypoint
is not displayed but it is the point where Direct To operation was
initiated. The course to fly while in this mode is referred to as the
desired track (Dtk). The desired track is displayed on the NAV 1
and may be selected for display on the NAV 4 page. To fly a
great circle course between two points, the desired track may be
constantly changing. A good way to illustrate this concept is with
a world globe and a piece of string. You can determine the great
circle path between Denver, Colorado and Manila, Philippines by
stretching the string over the globe between these two points.
Notice that you would start the flight with a northwesterly desired
track, which gradually becomes due westerly, and finally south-
westerly by the time you reach Manila. Of course, your trips with
the KLN 89(B) will be substantially shorter and the desired track
will probably change only a few degrees.
Automatic waypoint sequencing is provided during flight plan
operation. As you reach a waypoint in your flight plan, the next
leg of the flight plan automatically becomes active. ‡There are
some situations during approach operations in which automatic
leg sequencing is automatically disabled. See Chapter 5.
Turn anticipation may be utilized in flight plan operation as
described in section 4.2.2.
The Minimum Enroute Safe Altitude (ESA) displayed on the ALT
1 page is the highest MSA sector altitude from the present
position to the destination waypoint along the active flight plan or
Direct To route (whichever is in use). See section 3.12.
THE OBS MODE
The following are characteristics of the OBS mode.
The course deviation indicator (CDI) sensitivity is plus and minus
five nautical miles, full scale. This applies to the CDI on the NAV
1 page as well as any external CDIs or HSIs interfaced to the
KLN 89(B). If the CDI or HSI has five dots left and right of the
center position, then each dot represents one nautical mile of
The course is defined by the active waypoint and the selected
magnetic course. A course "to" or "from" the active waypoint may
Advanced GPS Operation
Advanced GPS Operation