Honeywell KLN 900s Pilot's Manual page 60

• Minimum Safe Altitude for present position (MSA) -
IMPORTANT: The minimum safe altitude displayed
is the altitude defined by Jeppesen as "Grid Minimum
Off-Route Altitude (Grid MORA)". This altitude is
derived by Jeppesen for sectors which are one degree
of latitude by one degree of longitude in size. One
degree of latitude is 60 nautical miles. One degree of
longitude is 60 nautical miles at the equator and pro-
gressively less than 60 nautical miles as one travels
away from the equator. One degree of longitude is
approximately 50 nautical miles at the southern most
parts of the U.S. and is approximately 40 nautical
miles at the northern most parts of the U.S. The MSA
altitude information is contained in the database and
is updated when the database cartridge is updated.
The minimum safe altitude (MSA) provides "reference
point" clearance within these one degree latitude by
one degree longitude sectors. Jeppesen defines a
reference point as "a natural (Peak, Knoll, Hill, Etc.) or
man-made (Tower, Stack, Tank, Building, etc.)
object". Jeppesen states the following about the Grid
Minimum Off-Route altitude: "Grid MORA values
ESA
(MSL)
MSA
(MSL)
1° LONG.
MINIMUM ENROUTE SAFE ALTITUDE (ESA)
clear all reference points by 1000 feet in areas where
the highest reference points are 5000 feet MSL or
lower. MORA values clear all reference points by
2000 feet in areas where the highest reference points
are 5001 feet MSL or higher". The KLN 900 displays
dashes for areas outside the database coverage area
or for areas where the Grid MORA is not defined.
• Minimum Enroute Safe Altitude (ESA). IMPORTANT:
When the KLN 900 is in the Leg mode, the minimum
enroute safe altitude is the highest MSA sector alti-
tude from the present position to the active waypoint,
then to the destination waypoint along the active flight
plan. See figure 3-106. When the KLN 900 is in the
OBS mode, the minimum enroute safe altitude is the
highest MSA sector altitude from the present position
to the active waypoint.
WARNING: The MSA and ESA altitudes displayed are
advisory in nature only. They should not be relied
upon as the sole source of obstacle and terrain
avoidance information. Refer to current aeronautical
charts for appropriate minimum clearance altitudes.
Figure 3-106
3-33
Rev 2