Garmin 500W Series Manual

A SERVICE OF

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2 - NAV PAGES

57

190-00357-00 Rev C

Each satellite has a 30-second data transmission

that must be collected (hollow signal strength bar)

before the satellite may be used for navigation (solid

signal strength bar). Once the GPS receiver has deter-

mined your position, the 500W-series unit indicates

your position, altitude, track and ground speed. The

GPS receiver status ﬁeld also displays the following

messages under the appropriate conditions:

•Searching Sky —

The GPS receiver is searching the sky for ANY vis-

ible satellites. You are also informed of this status

with a “Searching the Sky” message.

•AcquiringSat —

The GPS receiver is acquiring satellites for naviga-

tion. In this mode, the receiver uses satellite orbital

data (collected continuously from the satellites) and

last known position to determine the satellites that

should be in view.

•3DNavigation —

TheGPSreceiverisin3Dnavigationmodeand

computes altitude using satellite data.

•3DDifferentialNavigation—TheGPSreceiveris

in3Dnavigationmodeanddifferentialcorrections

are being used.

The Satellite Status Page also indicates the accu-

racy of the position ﬁx, using Horizontal Figure of

Merit (HFOM),VerticalFigureofMerit(VFOM), and

Estimated Position Uncertainty (EPU). HFOM and

VFOMrepresentthe95%condencelevelsinhori-

zontal and vertical accuracy. The lowest numbers are

the best accuracy and the highest numbers are worse.

EPU is the horizontal position error estimated by the

FaultDetectionandExclusion(FDE) algorithm, in feet

or meters.

Dead Reckoning

Deadreckoningistheprocessofcontinuingnavi-

gation using your last known position and speed after

a loss of GPS navigation while on an active ﬂight plan.

CAUTION: Navigation using dead reckoning is there-

fore only an estimate and should not be used as the

sole means of navigation. Use other means of naviga-

tion, if possible.

DeadreckoningbecomesactiveafteralossofGPS

position while you are navigating using an active ﬂight

plan.

A pop-up message will appear and you must clear

the message before continuing operation.

The ownship icon color is changed to yellow. The To/

FromagisremovedfromtheCDI.TheDeadReckon-

ingannunciator(DR)appearsontheleftsideofthe

map display when GPS position is unavailable and the

unitisinDeadReckoningmode.Allexternaloutputs

dependent on GPS position are ﬂagged.

Terrain will be noted as not available and new terrain

advisory pop-ops will not occur. Trafﬁc and Storm-

scope information will not be shown on the Map page,

but will continue to be available on their own dedi-

catedpages.XMweatherwillstillbeavailableonthe

Map page.

Dead Reckoning