Garmin GPS 400 Pilot's Manual And Reference page 46

NAV PAGES
1 5
PROCEDURES
Vertical Navigation
Approach Examples
(VNAV)
“
Œ

GPS accuracy may be degraded by the U.S.
Department of Defense-imposed Selective
Availability (SA) program. With "SA" on, GPS
altitude may be in error by several hundred
meters. Errors of this magnitude may result in
fluctuations in the VSR readout on the default
NAV page.
d
d
With the profile set, the vertical speed required (VSR) is displayed on the verti-
cal navigation page. Expect the following to occur when using the vertical naviga-
tion feature:
• At one minute prior to reaching the initial descent point, a message
"Approaching VNAV Profile" occurs. The descent (or climb) angle will also
lock to prevent changes in speed from altering the profile.
• If selected, the vertical speed required (VSR) readout on the default NAV and
map pages will show the desired vertical speed to maintain the proper descent
(or climb) angle.
• At 500 feet above (or below, for a climb) the target altitude, an "Approaching
Target Altitude" message is provided. The VSR readout on the default NAV
and map pages is blanked out, at this point.
Vertical navigation messages can be turned on or off. (By default the messages
are off.) Turning the messages off allows you to keep the profile settings you've
entered previously, without having them generate messages when the feature isn't
needed.
To disable/enable the vertical navigation (VNAV) messages:
m
E
a
E
E
E