BendixKing KLX 135A - Pilots Guide - Manual (Page 46)

3.6. INITIALIZATION AND TIME TO FIRST FIX
Since the KLX 135A 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 135A 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 135A to
reach a NAV ready condition, it is necessary to meet the following
conditions:
1. The KLX 135A’s “almanac” data must be current. Almanac data
is orbital information for all the satellites and is used for initial
acquisition when the KLX 135A is first turned on. This data is
stored in the KLX 135A’s non-volatile memory and is considered
current for up to six months. Each satellite sends almanac data
for all satellites. Since the KLX 135A routinely updates the
almanac data during normal operation, the almanac data will
become out of date only if the KLX 135A hasn’t been used for the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 135A 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 dis-
play 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 135A contains
KLX 135A Pilot’s Guide Basic GPS Operation
3-17 Effective Date 5/95 006-08789-0000 Rev 0
Basic GPS Operation
Chapter 3