Piper ARCHER III Pilot Operating Handbook page 210

SECTION
7
DESCRIPTION & OPERATION PA.28.181.
ARCHER
III
Multi-Function
Display (continued)
Terrain
Awareness and
Warning
System
(TAWS
-B)
-
Optional
NOII]
If
the
G1000 system
is
configured
to
use
the
optional Terrain Awareness and
Warning
System
(TAWS), Terain
Proximity
will
not be available
for
use.
The Terrain Awareness
and
Warning
System
(TAWS-B) is
an
optional feature
used
to increase situational awareness and
aid
in reducing controlled
flight
into
terrain
(CFIT). TAWS-B
provides visual
and
aural cautions and warning
alerts
when
terrain and obstacles
are
within
a
given altitude
threshold
from
the
aircraft.
The displayed alerts
and
warnings
are
advisory in
nature
only.
TAWS-B
satisfies
TSO-C15lb
Class
B certification requirements whereas
the
more
limited
Terain
Proximity
does not.
TAWS-B
uses
terrain
and
obstacle
information
supplied
by government
sources.
Terrain
information
is based on terrain elevation
infbrmation
in
a database that
may contain
inaccuracies.
Individual obstructions may
be
shown
if
available
in
the
database.
The
data
undergoes
verification
by
Garmin to confirm
accuracy
of
the content, per TSO-Cl51b
standards,
however, the displayed
information
should
never be understood
as
being all-inclusive
and data
may
be inaccurate.
WireAware
database
coverage
is
mostly
limited to tall
transmission
lines
and
their
associated
support structures.
It
does
not typically
have
information for
the smaller
utility
poles
or
lines.
WireAware obstacle database coverage exists
mainly
in
the
United
States;
with limited
coverage
in portions
of
Canada and
Mexico.
The
height of
the
wire obstacles is
commonly
estimated and
should not
be
relied upon
for
maneuvering decisions.
TAWS-B
uses
information provided
from
the GPS
receiver to
provide
a
horizontal
position and altitude. GPS altitude, derived
from
satellite
measurements, is
converted
to
the height above geodetic
sea
level
(GSL), which is
the
height
above
mean
sea
level
(MSL)
calculated geometrically.
GPS
position
and GSL
altitude
is
used
to
generate
TAWS-B
tenain
and
obstacle
alerts.
GSL
altitude
accuracy
is
affected
by
satellite geometry,
but is not
subject
to variations in
pressure and temperature
that normally affect
pressure
altitude
sensors.
GSL
altitude
does
not require local altimeter settings
to
determine
MSL
altitude.
REPORT;
VB-2749
7-26
ISSUED: December 22, 2017
REVISED:
Juty 3L,2018