Section 10 Fault Detection & Exclusion; Detection And Exclusion - Garmin GNS 400W Pilot's Manual & Reference

10 - FDE
Section 10
Fault Detection & Exclusion
The Garmin 400W-series software incorporates
a Fault Detection and Exclusion (FDE) algorithm,
thus providing a basis for approval per FAA Notice
N8110.60 requirements for "GPS as a Primary Means
of Navigation for Oceanic/Remote Operations".
The FDE consists of two distinct features, fault
detection and fault exclusion. The fault detection
feature detects the presence of an unacceptably large
pseudorange error for a satellite (and presumably,
position error) for a given mode of flight. Upon detec-
tion, fault exclusion follows and excludes the source
of the unacceptably large pseudorange error, thereby
allowing navigation to return to normal performance
without an interruption in service. To enhance safety,
FDE functionality is provided for other phases of flight
(non-precision approach, terminal, en route). The FDE
functionality for non-oceanic flight phases complies
with missed alert probability, false alert probability and
failed exclusion probability specified by DO-229C /
TSO-C146a.

Detection and Exclusion

An FDE prediction must be performed prior to
departure for a flight plan involving Oceanic/Remote
operation where GPS is to be the sole source of
navigation. Prior to departure, the operator must
use the FDE prediction program supplied with the
400W/500W-series Trainer CD to demonstrate that
there are no outages in the capability to navigate
on the specified route of flight (the FDE prediction
program determines whether the GPS constellation is
robust enough to provide a navigation solution for the
specified route of flight). Please, refer to the instruc-
tions included in the Garmin 400W/500W-series
180
Training CD for complete details on using the FDE
prediction program.
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