Principles Of Pulsed Airborne Weather Radar - Garmin G500 Pilot's Manual

Cover TOC
4.8.1.3

Principles of Pulsed Airborne Weather Radar

The term RADAR is an acronym for RAdio Detecting and Ranging. Pulsed
radar locates targets by transmitting a microwave pulse beam that, upon
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
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
returned signal is then processed and displayed on the G500/G600 MFD.
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
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.
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
depends on target intensity, spacing between the targets, aircraft capabilities and
pilot experience. Pulse type weather radar detects only precipitation, not clouds
or turbulence. The display may indicate clear areas between intense returns, but
this does not necessarily mean it is safe to fly between them. Only Doppler radar
can detect turbulence.
Airborne weather radar has other capabilities beyond weather detection. It
also has the ability to detect and provide distance to objects on the ground, such
as, cities, mountains, coastlines, rivers, lakes, and oceans.
4-92
Garmin G500/G600 Pilot's Guide 190-00601-02 Rev. J