Garmin GTN 725 Pilot's Manual page 336

12.3
Foreword
The GTN 7XX can display weather radar from a Garmin GWX system or from
Getting
selected 3rd party radars. Only one weather radar system may be interfaced to
Started
the system. For detailed information on the operation of 3rd party radars, refer
Audio &
to their specific documentation.
Xpdr Ctrl
12.3.1
Com/Nav
The Garmin GWX 68 and GWX 70 Airborne Color Weather Radars combine
FPL
excellent range and adjustable scanning profiles with a high-definition target
display.
Direct-To
To focus radar scanning on specific areas, Sector Scanning offers pilot-
adjustable horizontal scan angles of 20º, 40º, 60º, or 90º (up to 120º with the
Proc
GWX 70). A vertical scanning function helps to analyze storm tops, gradients,
Charts
and cell buildup activity at various altitudes.
See the documentation of each radar for specific features.
Wpt Info
12.3.1.1
Map
The term RADAR is an acronym for RAdio Detecting and Ranging. Pulsed
radar locates targets by transmitting a microwave pulse beam that, upon
Traffic
encountering a target, is then reflected back to the radar receiver as a return
"echo." The microwave pulses are focused and radiated by the antenna, with
Terrain
the most intense energy in the center of the beam and decreasing intensity near
the edge. The same antenna is used for both transmitting and receiving. The
Weather
returned signal is then processed and displayed on the GTN 7XX.
Nearest
Radar detection is a two-way process that requires 12.36 micro-seconds for
the transmitted microwave pulses to travel out and back for each nautical mile
Services/
Music
of target range. It takes 123.6 micro-seconds for a transmitted pulse to make the
round trip if a target is 10 NM away.
Utilities
The GWX weather radar should be used to avoid severe weather, not for
penetrating severe weather. The decision to fly into an area of radar targets
System
depends on target intensity, spacing between the targets, aircraft capabilities and
Messages
pilot experience. Pulse type weather radar detects only precipitation, not clouds
or turbulence. The display may indicate clear areas between intense returns, but
Symbols
this does not necessarily mean it is safe to fly between them. Only Doppler radar
can detect turbulence.
Appendix
12-32
Index
Weather Radar
Garmin GWX Radar Description
Principles of Pulsed Airborne Weather Radar
Garmin GTN 725/750 Pilot's Guide 190-01007-03 Rev. D