BendixKing KLN 900 - Pilots Guide - Manual (Page 44)

3-17 Rev 2
3.6 INITIALIZATION AND TIME TO FIRST FIX
Since the KLN 900 stores its position and other required
parameters in memory when power to the unit is removed,
it is seldom necessary to aid the unit in reaching a NAV
ready condition. The time required from power on until the
KLN 900 determines its present position and is therefore
ready to navigate is called “time to first fix.” The time to
first fix is normally a few minutes or less. In order for the
KLN 900 to reach a NAV ready condition, it is necessary
to meet the following conditions:
1. The KLN 900’s “almanac” data must be current.
Almanac data is crude orbital information for all the
satellites and is used for initial acquisition when the
KLN 900 is first turned on. This data is stored in the
KLN 900’s non-volatile memory and is considered cur-
rent for up to six months. Each satellite sends
almanac data for all satellites. Since the KLN 900 rou-
tinely updates the almanac data during normal opera-
tion, the almanac data will become out-of-date only if
the KLN 900 hasn’t been used for the previous six
months or longer. Collecting new almanac data takes
place automatically if the data is more than six months
old. If the almanac data is out-of-date and needs to be
collected, the KLN 900 will take a few minutes to
acquire your present position (usually about two min-
utes, but not more than 12 minutes). The Self Test
and Database pages should be approved.
2. The aircraft must be located such that the GPS
antenna has an unobstructed view of the sky so that
required satellite signals are not being blocked. If
necessary, position the aircraft away from hangars or
other obstructions.
3. It is very helpful for the KLN 900 to have the correct
time, date and position to be able to determine which
satellites should be in view. This information is stored
in the battery backed memory of the KLN 900 so it is
not normally required to update it. If the KLN 900 has
the correct time, date and position, then the time to first
fix will usually be less than two (2) minutes. If this infor-
mation is not correct, then the KLN 900 will start to look
for any satellites. Eventually, the KLN 900 will find
enough satellites to determine the position of the air-
craft. This process can take as long as 12 minutes. It is
possible for you to update this information manually
which will allow the KLN 900 to reach a NAV ready sta-
tus much faster. To set the time and date follow steps
6 and 7 in section 3.2, “Turn-On and Self-Test.” If it is
necessary to update the position then use the following
steps. Remember, if acquisition time is not important
then it is not necessary to update the time, date or
position.