Garmin GNS 430 Manuel d'utilisateur télécharger pdf (Page 171)

163

FDE

Section 10

Fault Detection & Exclusion

FDE is an acronym that stands for Fault Detection and Exclusion. FDE was incopor-

ated in the Garmin 400 Series Main and GPS Software version 3.00 and higher. FDE al-

gorithms, provide a basis for approval per the requirements for “GPS as a Primary Means

of Navigation for Oceanic/Remote Operations” per FAA Notice N8110.60. The oceanic

ﬂ ight phase is used by the GNS 430 when you are more than 200 nautical miles from the

nearest airport. There are two main aspects to address in the FDE system. The ﬁ rst

relates to the unit’s software side, in regard to detection and exclusion of faulty satellites.

This feature requires no pilot interaction during ﬂ ight. However, the second aspect is that

of predicting the capability of the GPS constellation to provide service during a ﬂ ight.

This is done by the pilot before the ﬂ ight.

Detection and Exclusion

FDE consists of two distinct parts, fault detection and fault exclusion. The detection

function refers to the capability to detect a satellite failure which can affect navigation.

Upon detection, the exclusion function will exclude one or more failed satellites and

prevent them from being used during navigation. This allows the GPS to return to nor-

mal performance without interruption. The process is entirely automated and does not

require pilot interaction during ﬂ ight. On the satellite satus page, the pilot can view infor-

mation related to FDE operation. To enhance safety, FDE functionality is provided for

other phases of ﬂ ight (non-precision approach, terminal, en route). The FDE functional-

ity for non-oceanic ﬂ ight phases adheres to the same missed alert probability, false alert

probability, and failed exclusion probability speciﬁ ed by N8110.60.

Oceanic Mode

Annunciation

Excluded Satellite

(checkered pattern)

Horizontal Uncertainty Level

SATELLITE STATUS PAGE

The Satellite Status Page above shows satellite number 9 exclusion dur-

ing oceanic phase of flight. No message notifying the user of exclusion

appears. In addition to the EPE and DOP fields, there is the Horizontal

Uncertainty Level (HUL) field which displays a 99% confidence level

that the aircraft position is within a circle with a radius of the value

displayed in the HUL field.

190-00140-00.indd 163 5/7/2003, 5:18:35 PM

1 2 ... 166 167 168 169 170 171 172 173 174 175 176 ... 203 204

Pas de commentaire

Garmin GNS 430 Manuel d'utilisateur Page 171