BendixKing KLX 135 - Pilots Guide - Manual (Page 48)

4.6. INITIALIZATION AND TIME TO FIRST FIX
Since the KLX 135 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 KLX 135 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 KLX 135 to
reach a NAV ready condition, it is necessary to meet the following
conditions:
1. The KLX 135’s “almanac” data must be current. Almanac data is
orbital information for all the satellites and is used for initial
acquisition when the KLX 135 is first turned on. This data is
stored in the KLX 135’s non-volatile memory and is considered
current for up to six months. Each satellite sends almanac data
for all satellites. Since the KLX 135 routinely updates the
almanac data during normal operation, the almanac data will
become out of date only if the KLX 135 hasn’t been used for the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.
The process of acquiring new almanac data is called a “Search
The Sky” start-up. The Search The Sky process requires that the
KLX 135 be turned on for a period of from 12.5 to 20 minutes and
that at least one satellite be in view. The Self Test, Initialization,
and Data Base pages should be approved. Almanac data is
being collected as long as the Other 1 (OTH 1) page displays
SRCH in the upper right corner. In addition, the message alert
will flash indicating there is a message to be viewed. If you press
the
C
button the message page will display a message stating:
*Search the Sky
Acquisition Started
Press
C
again to return to the previous page. The message
will remain active while the almanac data is being collected.
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 possible, position the aircraft away from
hangars or other obstructions.
3. The date and time displayed on the Initialization page or SET 2
page should be within 10 minutes of actual time. Date and time
are seldom a practical concern because the KLX 135 contains a
battery backed up calendar/clock. In addition, once a satellite is
KLX 135 Pilot’s Guide Basic GPS Operation
4-17 Effective Date 3/94 006-08751-0000 Rev 0
Basic GPS Operation
Chapter 4